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skia / skia / d0e3902c97b363ce29835c785a70121622b64f02 / . / src / sksl / codegen / SkSLMetalCodeGenerator.cpp
blob: 113b7dfd9f33765c38de0dc24cc41bbdcbab78a5 [file] [log] [blame]
/*
* Copyright 2016 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "src/sksl/codegen/SkSLMetalCodeGenerator.h"
#include "include/core/SkSpan.h"
#include "include/core/SkTypes.h"
#include "include/private/SkSLIRNode.h"
#include "include/private/SkSLLayout.h"
#include "include/private/SkSLModifiers.h"
#include "include/private/SkSLProgramElement.h"
#include "include/private/SkSLStatement.h"
#include "include/private/SkSLString.h"
#include "include/private/SkTo.h"
#include "include/sksl/SkSLErrorReporter.h"
#include "include/sksl/SkSLOperator.h"
#include "include/sksl/SkSLPosition.h"
#include "src/core/SkScopeExit.h"
#include "src/sksl/SkSLAnalysis.h"
#include "src/sksl/SkSLBuiltinTypes.h"
#include "src/sksl/SkSLCompiler.h"
#include "src/sksl/SkSLContext.h"
#include "src/sksl/SkSLIntrinsicList.h"
#include "src/sksl/SkSLMemoryLayout.h"
#include "src/sksl/SkSLOutputStream.h"
#include "src/sksl/SkSLProgramSettings.h"
#include "src/sksl/SkSLUtil.h"
#include "src/sksl/analysis/SkSLProgramVisitor.h"
#include "src/sksl/ir/SkSLBinaryExpression.h"
#include "src/sksl/ir/SkSLBlock.h"
#include "src/sksl/ir/SkSLConstructor.h"
#include "src/sksl/ir/SkSLConstructorArrayCast.h"
#include "src/sksl/ir/SkSLConstructorCompound.h"
#include "src/sksl/ir/SkSLConstructorMatrixResize.h"
#include "src/sksl/ir/SkSLDoStatement.h"
#include "src/sksl/ir/SkSLExpression.h"
#include "src/sksl/ir/SkSLExpressionStatement.h"
#include "src/sksl/ir/SkSLExtension.h"
#include "src/sksl/ir/SkSLFieldAccess.h"
#include "src/sksl/ir/SkSLForStatement.h"
#include "src/sksl/ir/SkSLFunctionCall.h"
#include "src/sksl/ir/SkSLFunctionDeclaration.h"
#include "src/sksl/ir/SkSLFunctionDefinition.h"
#include "src/sksl/ir/SkSLFunctionPrototype.h"
#include "src/sksl/ir/SkSLIfStatement.h"
#include "src/sksl/ir/SkSLIndexExpression.h"
#include "src/sksl/ir/SkSLInterfaceBlock.h"
#include "src/sksl/ir/SkSLLiteral.h"
#include "src/sksl/ir/SkSLModifiersDeclaration.h"
#include "src/sksl/ir/SkSLNop.h"
#include "src/sksl/ir/SkSLPostfixExpression.h"
#include "src/sksl/ir/SkSLPrefixExpression.h"
#include "src/sksl/ir/SkSLProgram.h"
#include "src/sksl/ir/SkSLReturnStatement.h"
#include "src/sksl/ir/SkSLSetting.h"
#include "src/sksl/ir/SkSLStructDefinition.h"
#include "src/sksl/ir/SkSLSwitchCase.h"
#include "src/sksl/ir/SkSLSwitchStatement.h"
#include "src/sksl/ir/SkSLSwizzle.h"
#include "src/sksl/ir/SkSLTernaryExpression.h"
#include "src/sksl/ir/SkSLVarDeclarations.h"
#include "src/sksl/ir/SkSLVariable.h"
#include "src/sksl/ir/SkSLVariableReference.h"
#include "src/sksl/spirv.h"
#include <algorithm>
#include <cstddef>
#include <functional>
#include <limits>
#include <memory>
namespace SkSL {
static const char* operator_name(Operator op) {
switch (op.kind()) {
case Operator::Kind::LOGICALXOR: return " != ";
default: return op.operatorName();
}
}
class MetalCodeGenerator::GlobalStructVisitor {
public:
virtual ~GlobalStructVisitor() = default;
virtual void visitInterfaceBlock(const InterfaceBlock& block, std::string_view blockName) {}
virtual void visitTexture(const Type& type, const Modifiers& modifiers,
std::string_view name) {}
virtual void visitSampler(const Type& type, std::string_view name) {}
virtual void visitConstantVariable(const VarDeclaration& decl) {}
virtual void visitNonconstantVariable(const Variable& var, const Expression* value) {}
};
class MetalCodeGenerator::ThreadgroupStructVisitor {
public:
virtual ~ThreadgroupStructVisitor() = default;
virtual void visitNonconstantVariable(const Variable& var) = 0;
};
void MetalCodeGenerator::write(std::string_view s) {
if (s.empty()) {
return;
}
if (fAtLineStart) {
for (int i = 0; i < fIndentation; i++) {
fOut->writeText(" ");
}
}
fOut->writeText(std::string(s).c_str());
fAtLineStart = false;
}
void MetalCodeGenerator::writeLine(std::string_view s) {
this->write(s);
fOut->writeText(fLineEnding);
fAtLineStart = true;
}
void MetalCodeGenerator::finishLine() {
if (!fAtLineStart) {
this->writeLine();
}
}
void MetalCodeGenerator::writeExtension(const Extension& ext) {
this->writeLine("#extension " + std::string(ext.name()) + " : enable");
}
std::string MetalCodeGenerator::typeName(const Type& type) {
// we need to know the modifiers for textures
switch (type.typeKind()) {
case Type::TypeKind::kArray:
SkASSERT(!type.isUnsizedArray());
SkASSERTF(type.columns() > 0, "invalid array size: %s", type.description().c_str());
return String::printf("array<%s, %d>",
this->typeName(type.componentType()).c_str(), type.columns());
case Type::TypeKind::kVector:
return this->typeName(type.componentType()) + std::to_string(type.columns());
case Type::TypeKind::kMatrix:
return this->typeName(type.componentType()) + std::to_string(type.columns()) + "x" +
std::to_string(type.rows());
case Type::TypeKind::kSampler:
if (type.dimensions() != SpvDim2D) {
fContext.fErrors->error(Position(), "Unsupported texture dimensions");
}
return "sampler2D";
case Type::TypeKind::kTexture:
switch (type.textureAccess()) {
case Type::TextureAccess::kSample: return "texture2d<half>";
case Type::TextureAccess::kRead: return "texture2d<half, access::read>";
case Type::TextureAccess::kWrite: return "texture2d<half, access::write>";
case Type::TextureAccess::kReadWrite: return "texture2d<half, access::read_write>";
default: SkUNREACHABLE;
}
break;
default:
return std::string(type.name());
}
}
void MetalCodeGenerator::writeStructDefinition(const StructDefinition& s) {
const Type& type = s.type();
this->writeLine("struct " + type.displayName() + " {");
fIndentation++;
this->writeFields(type.fields(), type.fPosition);
fIndentation--;
this->writeLine("};");
}
void MetalCodeGenerator::writeType(const Type& type) {
this->write(this->typeName(type));
}
void MetalCodeGenerator::writeExpression(const Expression& expr, Precedence parentPrecedence) {
switch (expr.kind()) {
case Expression::Kind::kBinary:
this->writeBinaryExpression(expr.as<BinaryExpression>(), parentPrecedence);
break;
case Expression::Kind::kConstructorArray:
case Expression::Kind::kConstructorStruct:
this->writeAnyConstructor(expr.asAnyConstructor(), "{", "}", parentPrecedence);
break;
case Expression::Kind::kConstructorArrayCast:
this->writeConstructorArrayCast(expr.as<ConstructorArrayCast>(), parentPrecedence);
break;
case Expression::Kind::kConstructorCompound:
this->writeConstructorCompound(expr.as<ConstructorCompound>(), parentPrecedence);
break;
case Expression::Kind::kConstructorDiagonalMatrix:
case Expression::Kind::kConstructorSplat:
this->writeAnyConstructor(expr.asAnyConstructor(), "(", ")", parentPrecedence);
break;
case Expression::Kind::kConstructorMatrixResize:
this->writeConstructorMatrixResize(expr.as<ConstructorMatrixResize>(),
parentPrecedence);
break;
case Expression::Kind::kConstructorScalarCast:
case Expression::Kind::kConstructorCompoundCast:
this->writeCastConstructor(expr.asAnyConstructor(), "(", ")", parentPrecedence);
break;
case Expression::Kind::kFieldAccess:
this->writeFieldAccess(expr.as<FieldAccess>());
break;
case Expression::Kind::kLiteral:
this->writeLiteral(expr.as<Literal>());
break;
case Expression::Kind::kFunctionCall:
this->writeFunctionCall(expr.as<FunctionCall>());
break;
case Expression::Kind::kPrefix:
this->writePrefixExpression(expr.as<PrefixExpression>(), parentPrecedence);
break;
case Expression::Kind::kPostfix:
this->writePostfixExpression(expr.as<PostfixExpression>(), parentPrecedence);
break;
case Expression::Kind::kSetting:
this->writeExpression(*expr.as<Setting>().toLiteral(fContext), parentPrecedence);
break;
case Expression::Kind::kSwizzle:
this->writeSwizzle(expr.as<Swizzle>());
break;
case Expression::Kind::kVariableReference:
this->writeVariableReference(expr.as<VariableReference>());
break;
case Expression::Kind::kTernary:
this->writeTernaryExpression(expr.as<TernaryExpression>(), parentPrecedence);
break;
case Expression::Kind::kIndex:
this->writeIndexExpression(expr.as<IndexExpression>());
break;
default:
SkDEBUGFAILF("unsupported expression: %s", expr.description().c_str());
break;
}
}
// returns true if we should pass by reference instead of by value
static bool pass_by_reference(const Type& type, const Modifiers& modifiers) {
return (modifiers.fFlags & Modifiers::kOut_Flag) && !type.isUnsizedArray();
}
// returns true if we need to specify an address space modifier
static bool needs_address_space(const Type& type, const Modifiers& modifiers) {
return type.isUnsizedArray() || pass_by_reference(type, modifiers);
}
// returns true if the InterfaceBlock has the `buffer` modifier
static bool is_buffer(const InterfaceBlock& block) {
return block.var()->modifiers().fFlags & Modifiers::kBuffer_Flag;
}
// returns true if the InterfaceBlock has the `readonly` modifier
static bool is_readonly(const InterfaceBlock& block) {
return block.var()->modifiers().fFlags & Modifiers::kReadOnly_Flag;
}
std::string MetalCodeGenerator::getOutParamHelper(const FunctionCall& call,
const ExpressionArray& arguments,
const SkTArray<VariableReference*>& outVars) {
AutoOutputStream outputToExtraFunctions(this, &fExtraFunctions, &fIndentation);
const FunctionDeclaration& function = call.function();
std::string name = "_skOutParamHelper" + std::to_string(fSwizzleHelperCount++) +
"_" + function.mangledName();
const char* separator = "";
// Emit a prototype for the function we'll be calling through to in our helper.
if (!function.isBuiltin()) {
this->writeFunctionDeclaration(function);
this->writeLine(";");
}
// Synthesize a helper function that takes the same inputs as `function`, except in places where
// `outVars` is non-null; in those places, we take the type of the VariableReference.
//
// float _skOutParamHelper0_originalFuncName(float _var0, float _var1, float& outParam) {
this->writeType(call.type());
this->write(" ");
this->write(name);
this->write("(");
this->writeFunctionRequirementParams(function, separator);
SkASSERT(outVars.size() == arguments.size());
SkASSERT(SkToSizeT(outVars.size()) == function.parameters().size());
// We need to detect cases where the caller passes the same variable as an out-param more than
// once, and avoid reusing the variable name. (In those cases we can actually just ignore the
// redundant input parameter entirely, and not give it any name.)
SkTHashSet<const Variable*> writtenVars;
for (int index = 0; index < arguments.size(); ++index) {
this->write(separator);
separator = ", ";
const Variable* param = function.parameters()[index];
this->writeModifiers(param->modifiers());
const Type* type = outVars[index] ? &outVars[index]->type() : &arguments[index]->type();
this->writeType(*type);
if (pass_by_reference(param->type(), param->modifiers())) {
this->write("&");
}
if (outVars[index]) {
const Variable* var = outVars[index]->variable();
if (!writtenVars.contains(var)) {
writtenVars.add(var);
this->write(" ");
fIgnoreVariableReferenceModifiers = true;
this->writeVariableReference(*outVars[index]);
fIgnoreVariableReferenceModifiers = false;
}
} else {
this->write(" _var");
this->write(std::to_string(index));
}
}
this->writeLine(") {");
++fIndentation;
for (int index = 0; index < outVars.size(); ++index) {
if (!outVars[index]) {
continue;
}
// float3 _var2[ = outParam.zyx];
this->writeType(arguments[index]->type());
this->write(" _var");
this->write(std::to_string(index));
const Variable* param = function.parameters()[index];
if (param->modifiers().fFlags & Modifiers::kIn_Flag) {
this->write(" = ");
fIgnoreVariableReferenceModifiers = true;
this->writeExpression(*arguments[index], Precedence::kAssignment);
fIgnoreVariableReferenceModifiers = false;
}
this->writeLine(";");
}
// [int _skResult = ] myFunction(inputs, outputs, _globals, _var0, _var1, _var2, _var3);
bool hasResult = (call.type().name() != "void");
if (hasResult) {
this->writeType(call.type());
this->write(" _skResult = ");
}
this->writeName(function.mangledName());
this->write("(");
separator = "";
this->writeFunctionRequirementArgs(function, separator);
for (int index = 0; index < arguments.size(); ++index) {
this->write(separator);
separator = ", ";
this->write("_var");
this->write(std::to_string(index));
}
this->writeLine(");");
for (int index = 0; index < outVars.size(); ++index) {
if (!outVars[index]) {
continue;
}
// outParam.zyx = _var2;
fIgnoreVariableReferenceModifiers = true;
this->writeExpression(*arguments[index], Precedence::kAssignment);
fIgnoreVariableReferenceModifiers = false;
this->write(" = _var");
this->write(std::to_string(index));
this->writeLine(";");
}
if (hasResult) {
this->writeLine("return _skResult;");
}
--fIndentation;
this->writeLine("}");
return name;
}
std::string MetalCodeGenerator::getBitcastIntrinsic(const Type& outType) {
return "as_type<" + outType.displayName() + ">";
}
void MetalCodeGenerator::writeFunctionCall(const FunctionCall& c) {
const FunctionDeclaration& function = c.function();
// Many intrinsics need to be rewritten in Metal.
if (function.isIntrinsic()) {
if (this->writeIntrinsicCall(c, function.intrinsicKind())) {
return;
}
}
// Determine whether or not we need to emulate GLSL's out-param semantics for Metal using a
// helper function. (Specifically, out-parameters in GLSL are only written back to the original
// variable at the end of the function call; also, swizzles are supported, whereas Metal doesn't
// allow a swizzle to be passed to a `floatN&`.)
const ExpressionArray& arguments = c.arguments();
const std::vector<Variable*>& parameters = function.parameters();
SkASSERT(SkToSizeT(arguments.size()) == parameters.size());
bool foundOutParam = false;
SkSTArray<16, VariableReference*> outVars;
outVars.push_back_n(arguments.size(), (VariableReference*)nullptr);
for (int index = 0; index < arguments.size(); ++index) {
// If this is an out parameter...
if (parameters[index]->modifiers().fFlags & Modifiers::kOut_Flag) {
// Find the expression's inner variable being written to.
Analysis::AssignmentInfo info;
// Assignability was verified at IRGeneration time, so this should always succeed.
SkAssertResult(Analysis::IsAssignable(*arguments[index], &info));
outVars[index] = info.fAssignedVar;
foundOutParam = true;
}
}
if (foundOutParam) {
// Out parameters need to be written back to at the end of the function. To do this, we
// synthesize a helper function which evaluates the out-param expression into a temporary
// variable, calls the original function, then writes the temp var back into the out param
// using the original out-param expression. (This lets us support things like swizzles and
// array indices.)
this->write(getOutParamHelper(c, arguments, outVars));
} else {
this->write(function.mangledName());
}
this->write("(");
const char* separator = "";
this->writeFunctionRequirementArgs(function, separator);
for (int i = 0; i < arguments.size(); ++i) {
this->write(separator);
separator = ", ";
if (outVars[i]) {
this->writeExpression(*outVars[i], Precedence::kSequence);
} else {
this->writeExpression(*arguments[i], Precedence::kSequence);
}
}
this->write(")");
}
static constexpr char kInverse2x2[] = R"(
template <typename T>
matrix<T, 2, 2> mat2_inverse(matrix<T, 2, 2> m) {
return matrix<T, 2, 2>(m[1].y, -m[0].y, -m[1].x, m[0].x) * (1/determinant(m));
}
)";
static constexpr char kInverse3x3[] = R"(
template <typename T>
matrix<T, 3, 3> mat3_inverse(matrix<T, 3, 3> m) {
T
a00 = m[0].x, a01 = m[0].y, a02 = m[0].z,
a10 = m[1].x, a11 = m[1].y, a12 = m[1].z,
a20 = m[2].x, a21 = m[2].y, a22 = m[2].z,
b01 = a22*a11 - a12*a21,
b11 = -a22*a10 + a12*a20,
b21 = a21*a10 - a11*a20,
det = a00*b01 + a01*b11 + a02*b21;
return matrix<T, 3, 3>(
b01, (-a22*a01 + a02*a21), ( a12*a01 - a02*a11),
b11, ( a22*a00 - a02*a20), (-a12*a00 + a02*a10),
b21, (-a21*a00 + a01*a20), ( a11*a00 - a01*a10)) * (1/det);
}
)";
static constexpr char kInverse4x4[] = R"(
template <typename T>
matrix<T, 4, 4> mat4_inverse(matrix<T, 4, 4> m) {
T
a00 = m[0].x, a01 = m[0].y, a02 = m[0].z, a03 = m[0].w,
a10 = m[1].x, a11 = m[1].y, a12 = m[1].z, a13 = m[1].w,
a20 = m[2].x, a21 = m[2].y, a22 = m[2].z, a23 = m[2].w,
a30 = m[3].x, a31 = m[3].y, a32 = m[3].z, a33 = m[3].w,
b00 = a00*a11 - a01*a10,
b01 = a00*a12 - a02*a10,
b02 = a00*a13 - a03*a10,
b03 = a01*a12 - a02*a11,
b04 = a01*a13 - a03*a11,
b05 = a02*a13 - a03*a12,
b06 = a20*a31 - a21*a30,
b07 = a20*a32 - a22*a30,
b08 = a20*a33 - a23*a30,
b09 = a21*a32 - a22*a31,
b10 = a21*a33 - a23*a31,
b11 = a22*a33 - a23*a32,
det = b00*b11 - b01*b10 + b02*b09 + b03*b08 - b04*b07 + b05*b06;
return matrix<T, 4, 4>(
a11*b11 - a12*b10 + a13*b09,
a02*b10 - a01*b11 - a03*b09,
a31*b05 - a32*b04 + a33*b03,
a22*b04 - a21*b05 - a23*b03,
a12*b08 - a10*b11 - a13*b07,
a00*b11 - a02*b08 + a03*b07,
a32*b02 - a30*b05 - a33*b01,
a20*b05 - a22*b02 + a23*b01,
a10*b10 - a11*b08 + a13*b06,
a01*b08 - a00*b10 - a03*b06,
a30*b04 - a31*b02 + a33*b00,
a21*b02 - a20*b04 - a23*b00,
a11*b07 - a10*b09 - a12*b06,
a00*b09 - a01*b07 + a02*b06,
a31*b01 - a30*b03 - a32*b00,
a20*b03 - a21*b01 + a22*b00) * (1/det);
}
)";
std::string MetalCodeGenerator::getInversePolyfill(const ExpressionArray& arguments) {
// Only use polyfills for a function taking a single-argument square matrix.
SkASSERT(arguments.size() == 1);
const Type& type = arguments.front()->type();
if (type.isMatrix() && type.rows() == type.columns()) {
switch (type.rows()) {
case 2:
if (!fWrittenInverse2) {
fWrittenInverse2 = true;
fExtraFunctions.writeText(kInverse2x2);
}
return "mat2_inverse";
case 3:
if (!fWrittenInverse3) {
fWrittenInverse3 = true;
fExtraFunctions.writeText(kInverse3x3);
}
return "mat3_inverse";
case 4:
if (!fWrittenInverse4) {
fWrittenInverse4 = true;
fExtraFunctions.writeText(kInverse4x4);
}
return "mat4_inverse";
}
}
SkDEBUGFAILF("no polyfill for inverse(%s)", type.description().c_str());
return "inverse";
}
void MetalCodeGenerator::writeMatrixCompMult() {
static constexpr char kMatrixCompMult[] = R"(
template <typename T, int C, int R>
matrix<T, C, R> matrixCompMult(matrix<T, C, R> a, const matrix<T, C, R> b) {
for (int c = 0; c < C; ++c) { a[c] *= b[c]; }
return a;
}
)";
if (!fWrittenMatrixCompMult) {
fWrittenMatrixCompMult = true;
fExtraFunctions.writeText(kMatrixCompMult);
}
}
void MetalCodeGenerator::writeOuterProduct() {
static constexpr char kOuterProduct[] = R"(
template <typename T, int C, int R>
matrix<T, C, R> outerProduct(const vec<T, R> a, const vec<T, C> b) {
matrix<T, C, R> m;
for (int c = 0; c < C; ++c) { m[c] = a * b[c]; }
return m;
}
)";
if (!fWrittenOuterProduct) {
fWrittenOuterProduct = true;
fExtraFunctions.writeText(kOuterProduct);
}
}
std::string MetalCodeGenerator::getTempVariable(const Type& type) {
std::string tempVar = "_skTemp" + std::to_string(fVarCount++);
this->fFunctionHeader += " " + this->typeName(type) + " " + tempVar + ";\n";
return tempVar;
}
void MetalCodeGenerator::writeSimpleIntrinsic(const FunctionCall& c) {
// Write out an intrinsic function call exactly as-is. No muss no fuss.
this->write(c.function().name());
this->writeArgumentList(c.arguments());
}
void MetalCodeGenerator::writeArgumentList(const ExpressionArray& arguments) {
this->write("(");
const char* separator = "";
for (const std::unique_ptr<Expression>& arg : arguments) {
this->write(separator);
separator = ", ";
this->writeExpression(*arg, Precedence::kSequence);
}
this->write(")");
}
bool MetalCodeGenerator::writeIntrinsicCall(const FunctionCall& c, IntrinsicKind kind) {
const ExpressionArray& arguments = c.arguments();
switch (kind) {
case k_read_IntrinsicKind: {
this->writeExpression(*arguments[0], Precedence::kTopLevel);
this->write(".read(");
this->writeExpression(*arguments[1], Precedence::kSequence);
this->write(")");
return true;
}
case k_write_IntrinsicKind: {
this->writeExpression(*arguments[0], Precedence::kTopLevel);
this->write(".write(");
this->writeExpression(*arguments[2], Precedence::kSequence);
this->write(", ");
this->writeExpression(*arguments[1], Precedence::kSequence);
this->write(")");
return true;
}
case k_width_IntrinsicKind: {
this->writeExpression(*arguments[0], Precedence::kTopLevel);
this->write(".get_width()");
return true;
}
case k_height_IntrinsicKind: {
this->writeExpression(*arguments[0], Precedence::kTopLevel);
this->write(".get_height()");
return true;
}
case k_mod_IntrinsicKind: {
// fmod(x, y) in metal calculates x - y * trunc(x / y) instead of x - y * floor(x / y)
std::string tmpX = this->getTempVariable(arguments[0]->type());
std::string tmpY = this->getTempVariable(arguments[1]->type());
this->write("(" + tmpX + " = ");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write(", " + tmpY + " = ");
this->writeExpression(*arguments[1], Precedence::kSequence);
this->write(", " + tmpX + " - " + tmpY + " * floor(" + tmpX + " / " + tmpY + "))");
return true;
}
// GLSL declares scalar versions of most geometric intrinsics, but these don't exist in MSL
case k_distance_IntrinsicKind: {
if (arguments[0]->type().columns() == 1) {
this->write("abs(");
this->writeExpression(*arguments[0], Precedence::kAdditive);
this->write(" - ");
this->writeExpression(*arguments[1], Precedence::kAdditive);
this->write(")");
} else {
this->writeSimpleIntrinsic(c);
}
return true;
}
case k_dot_IntrinsicKind: {
if (arguments[0]->type().columns() == 1) {
this->write("(");
this->writeExpression(*arguments[0], Precedence::kMultiplicative);
this->write(" * ");
this->writeExpression(*arguments[1], Precedence::kMultiplicative);
this->write(")");
} else {
this->writeSimpleIntrinsic(c);
}
return true;
}
case k_faceforward_IntrinsicKind: {
if (arguments[0]->type().columns() == 1) {
// ((((Nref) * (I) < 0) ? 1 : -1) * (N))
this->write("((((");
this->writeExpression(*arguments[2], Precedence::kSequence);
this->write(") * (");
this->writeExpression(*arguments[1], Precedence::kSequence);
this->write(") < 0) ? 1 : -1) * (");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write("))");
} else {
this->writeSimpleIntrinsic(c);
}
return true;
}
case k_length_IntrinsicKind: {
this->write(arguments[0]->type().columns() == 1 ? "abs(" : "length(");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write(")");
return true;
}
case k_normalize_IntrinsicKind: {
this->write(arguments[0]->type().columns() == 1 ? "sign(" : "normalize(");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write(")");
return true;
}
case k_packUnorm2x16_IntrinsicKind: {
this->write("pack_float_to_unorm2x16(");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write(")");
return true;
}
case k_unpackUnorm2x16_IntrinsicKind: {
this->write("unpack_unorm2x16_to_float(");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write(")");
return true;
}
case k_packSnorm2x16_IntrinsicKind: {
this->write("pack_float_to_snorm2x16(");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write(")");
return true;
}
case k_unpackSnorm2x16_IntrinsicKind: {
this->write("unpack_snorm2x16_to_float(");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write(")");
return true;
}
case k_packUnorm4x8_IntrinsicKind: {
this->write("pack_float_to_unorm4x8(");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write(")");
return true;
}
case k_unpackUnorm4x8_IntrinsicKind: {
this->write("unpack_unorm4x8_to_float(");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write(")");
return true;
}
case k_packSnorm4x8_IntrinsicKind: {
this->write("pack_float_to_snorm4x8(");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write(")");
return true;
}
case k_unpackSnorm4x8_IntrinsicKind: {
this->write("unpack_snorm4x8_to_float(");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write(")");
return true;
}
case k_packHalf2x16_IntrinsicKind: {
this->write("as_type<uint>(half2(");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write("))");
return true;
}
case k_unpackHalf2x16_IntrinsicKind: {
this->write("float2(as_type<half2>(");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write("))");
return true;
}
case k_floatBitsToInt_IntrinsicKind:
case k_floatBitsToUint_IntrinsicKind:
case k_intBitsToFloat_IntrinsicKind:
case k_uintBitsToFloat_IntrinsicKind: {
this->write(this->getBitcastIntrinsic(c.type()));
this->write("(");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write(")");
return true;
}
case k_degrees_IntrinsicKind: {
this->write("((");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write(") * 57.2957795)");
return true;
}
case k_radians_IntrinsicKind: {
this->write("((");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write(") * 0.0174532925)");
return true;
}
case k_dFdx_IntrinsicKind: {
this->write("dfdx");
this->writeArgumentList(c.arguments());
return true;
}
case k_dFdy_IntrinsicKind: {
if (!fRTFlipName.empty()) {
this->write("(" + fRTFlipName + ".y * dfdy");
} else {
this->write("(dfdy");
}
this->writeArgumentList(c.arguments());
this->write(")");
return true;
}
case k_inverse_IntrinsicKind: {
this->write(this->getInversePolyfill(arguments));
this->writeArgumentList(c.arguments());
return true;
}
case k_inversesqrt_IntrinsicKind: {
this->write("rsqrt");
this->writeArgumentList(c.arguments());
return true;
}
case k_atan_IntrinsicKind: {
this->write(c.arguments().size() == 2 ? "atan2" : "atan");
this->writeArgumentList(c.arguments());
return true;
}
case k_reflect_IntrinsicKind: {
if (arguments[0]->type().columns() == 1) {
// We need to synthesize `I - 2 * N * I * N`.
std::string tmpI = this->getTempVariable(arguments[0]->type());
std::string tmpN = this->getTempVariable(arguments[1]->type());
// (_skTempI = ...
this->write("(" + tmpI + " = ");
this->writeExpression(*arguments[0], Precedence::kSequence);
// , _skTempN = ...
this->write(", " + tmpN + " = ");
this->writeExpression(*arguments[1], Precedence::kSequence);
// , _skTempI - 2 * _skTempN * _skTempI * _skTempN)
this->write(", " + tmpI + " - 2 * " + tmpN + " * " + tmpI + " * " + tmpN + ")");
} else {
this->writeSimpleIntrinsic(c);
}
return true;
}
case k_refract_IntrinsicKind: {
if (arguments[0]->type().columns() == 1) {
// Metal does implement refract for vectors; rather than reimplementing refract from
// scratch, we can replace the call with `refract(float2(I,0), float2(N,0), eta).x`.
this->write("(refract(float2(");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write(", 0), float2(");
this->writeExpression(*arguments[1], Precedence::kSequence);
this->write(", 0), ");
this->writeExpression(*arguments[2], Precedence::kSequence);
this->write(").x)");
} else {
this->writeSimpleIntrinsic(c);
}
return true;
}
case k_roundEven_IntrinsicKind: {
this->write("rint");
this->writeArgumentList(c.arguments());
return true;
}
case k_bitCount_IntrinsicKind: {
this->write("popcount(");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write(")");
return true;
}
case k_findLSB_IntrinsicKind: {
// Create a temp variable to store the expression, to avoid double-evaluating it.
std::string skTemp = this->getTempVariable(arguments[0]->type());
std::string exprType = this->typeName(arguments[0]->type());
// ctz returns numbits(type) on zero inputs; GLSL documents it as generating -1 instead.
// Use select to detect zero inputs and force a -1 result.
// (_skTemp1 = (.....), select(ctz(_skTemp1), int4(-1), _skTemp1 == int4(0)))
this->write("(");
this->write(skTemp);
this->write(" = (");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write("), select(ctz(");
this->write(skTemp);
this->write("), ");
this->write(exprType);
this->write("(-1), ");
this->write(skTemp);
this->write(" == ");
this->write(exprType);
this->write("(0)))");
return true;
}
case k_findMSB_IntrinsicKind: {
// Create a temp variable to store the expression, to avoid double-evaluating it.
std::string skTemp1 = this->getTempVariable(arguments[0]->type());
std::string exprType = this->typeName(arguments[0]->type());
// GLSL findMSB is actually quite different from Metal's clz:
// - For signed negative numbers, it returns the first zero bit, not the first one bit!
// - For an empty input (0/~0 depending on sign), findMSB gives -1; clz is numbits(type)
// (_skTemp1 = (.....),
this->write("(");
this->write(skTemp1);
this->write(" = (");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write("), ");
// Signed input types might be negative; we need another helper variable to negate the
// input (since we can only find one bits, not zero bits).
std::string skTemp2;
if (arguments[0]->type().isSigned()) {
// ... _skTemp2 = (select(_skTemp1, ~_skTemp1, _skTemp1 < 0)),
skTemp2 = this->getTempVariable(arguments[0]->type());
this->write(skTemp2);
this->write(" = (select(");
this->write(skTemp1);
this->write(", ~");
this->write(skTemp1);
this->write(", ");
this->write(skTemp1);
this->write(" < 0)), ");
} else {
skTemp2 = skTemp1;
}
// ... select(int4(clz(_skTemp2)), int4(-1), _skTemp2 == int4(0)))
this->write("select(");
this->write(this->typeName(c.type()));
this->write("(clz(");
this->write(skTemp2);
this->write(")), ");
this->write(this->typeName(c.type()));
this->write("(-1), ");
this->write(skTemp2);
this->write(" == ");
this->write(exprType);
this->write("(0)))");
return true;
}
case k_sign_IntrinsicKind: {
if (arguments[0]->type().componentType().isInteger()) {
// Create a temp variable to store the expression, to avoid double-evaluating it.
std::string skTemp = this->getTempVariable(arguments[0]->type());
std::string exprType = this->typeName(arguments[0]->type());
// (_skTemp = (.....),
this->write("(");
this->write(skTemp);
this->write(" = (");
this->writeExpression(*arguments[0], Precedence::kSequence);
this->write("), ");
// ... select(select(int4(0), int4(-1), _skTemp < 0), int4(1), _skTemp > 0))
this->write("select(select(");
this->write(exprType);
this->write("(0), ");
this->write(exprType);
this->write("(-1), ");
this->write(skTemp);
this->write(" < 0), ");
this->write(exprType);
this->write("(1), ");
this->write(skTemp);
this->write(" > 0))");
} else {
this->writeSimpleIntrinsic(c);
}
return true;
}
case k_matrixCompMult_IntrinsicKind: {
this->writeMatrixCompMult();
this->writeSimpleIntrinsic(c);
return true;
}
case k_outerProduct_IntrinsicKind: {
this->writeOuterProduct();
this->writeSimpleIntrinsic(c);
return true;
}
case k_mix_IntrinsicKind: {
SkASSERT(c.arguments().size() == 3);
if (arguments[2]->type().componentType().isBoolean()) {
// The Boolean forms of GLSL mix() use the select() intrinsic in Metal.
this->write("select");
this->writeArgumentList(c.arguments());
return true;
}
// The basic form of mix() is supported by Metal as-is.
this->writeSimpleIntrinsic(c);
return true;
}
case k_equal_IntrinsicKind:
case k_greaterThan_IntrinsicKind:
case k_greaterThanEqual_IntrinsicKind:
case k_lessThan_IntrinsicKind:
case k_lessThanEqual_IntrinsicKind:
case k_notEqual_IntrinsicKind: {
this->write("(");
this->writeExpression(*c.arguments()[0], Precedence::kRelational);
switch (kind) {
case k_equal_IntrinsicKind:
this->write(" == ");
break;
case k_notEqual_IntrinsicKind:
this->write(" != ");
break;
case k_lessThan_IntrinsicKind:
this->write(" < ");
break;
case k_lessThanEqual_IntrinsicKind:
this->write(" <= ");
break;
case k_greaterThan_IntrinsicKind:
this->write(" > ");
break;
case k_greaterThanEqual_IntrinsicKind:
this->write(" >= ");
break;
default:
SK_ABORT("unsupported comparison intrinsic kind");
}
this->writeExpression(*c.arguments()[1], Precedence::kRelational);
this->write(")");
return true;
}
case k_storageBarrier_IntrinsicKind:
this->write("threadgroup_barrier(mem_flags::mem_device)");
return true;
case k_workgroupBarrier_IntrinsicKind:
this->write("threadgroup_barrier(mem_flags::mem_threadgroup)");
return true;
default:
return false;
}
}
// Assembles a matrix of type floatRxC by resizing another matrix named `x0`.
// Cells that don't exist in the source matrix will be populated with identity-matrix values.
void MetalCodeGenerator::assembleMatrixFromMatrix(const Type& sourceMatrix, int rows, int columns) {
SkASSERT(rows <= 4);
SkASSERT(columns <= 4);
std::string matrixType = this->typeName(sourceMatrix.componentType());
const char* separator = "";
for (int c = 0; c < columns; ++c) {
fExtraFunctions.printf("%s%s%d(", separator, matrixType.c_str(), rows);
separator = "), ";
// Determine how many values to take from the source matrix for this row.
int swizzleLength = 0;
if (c < sourceMatrix.columns()) {
swizzleLength = std::min<>(rows, sourceMatrix.rows());
}
// Emit all the values from the source matrix row.
bool firstItem;
switch (swizzleLength) {
case 0: firstItem = true; break;
case 1: firstItem = false; fExtraFunctions.printf("x0[%d].x", c); break;
case 2: firstItem = false; fExtraFunctions.printf("x0[%d].xy", c); break;
case 3: firstItem = false; fExtraFunctions.printf("x0[%d].xyz", c); break;
case 4: firstItem = false; fExtraFunctions.printf("x0[%d].xyzw", c); break;
default: SkUNREACHABLE;
}
// Emit the placeholder identity-matrix cells.
for (int r = swizzleLength; r < rows; ++r) {
fExtraFunctions.printf("%s%s", firstItem ? "" : ", ", (r == c) ? "1.0" : "0.0");
firstItem = false;
}
}
fExtraFunctions.writeText(")");
}
// Assembles a matrix of type floatCxR by concatenating an arbitrary mix of values, named `x0`,
// `x1`, etc. An error is written if the expression list don't contain exactly C*R scalars.
void MetalCodeGenerator::assembleMatrixFromExpressions(const AnyConstructor& ctor,
int columns, int rows) {
SkASSERT(rows <= 4);
SkASSERT(columns <= 4);
std::string matrixType = this->typeName(ctor.type().componentType());
size_t argIndex = 0;
int argPosition = 0;
auto args = ctor.argumentSpan();
static constexpr char kSwizzle[] = "xyzw";
const char* separator = "";
for (int c = 0; c < columns; ++c) {
fExtraFunctions.printf("%s%s%d(", separator, matrixType.c_str(), rows);
separator = "), ";
const char* columnSeparator = "";
for (int r = 0; r < rows;) {
fExtraFunctions.writeText(columnSeparator);
columnSeparator = ", ";
if (argIndex < args.size()) {
const Type& argType = args[argIndex]->type();
switch (argType.typeKind()) {
case Type::TypeKind::kScalar: {
fExtraFunctions.printf("x%zu", argIndex);
++r;
++argPosition;
break;
}
case Type::TypeKind::kVector: {
fExtraFunctions.printf("x%zu.", argIndex);
do {
fExtraFunctions.write8(kSwizzle[argPosition]);
++r;
++argPosition;
} while (r < rows && argPosition < argType.columns());
break;
}
case Type::TypeKind::kMatrix: {
fExtraFunctions.printf("x%zu[%d].", argIndex, argPosition / argType.rows());
do {
fExtraFunctions.write8(kSwizzle[argPosition]);
++r;
++argPosition;
} while (r < rows && (argPosition % argType.rows()) != 0);
break;
}
default: {
SkDEBUGFAIL("incorrect type of argument for matrix constructor");
fExtraFunctions.writeText("<error>");
break;
}
}
if (argPosition >= argType.columns() * argType.rows()) {
++argIndex;
argPosition = 0;
}
} else {
SkDEBUGFAIL("not enough arguments for matrix constructor");
fExtraFunctions.writeText("<error>");
}
}
}
if (argPosition != 0 || argIndex != args.size()) {
SkDEBUGFAIL("incorrect number of arguments for matrix constructor");
fExtraFunctions.writeText(", <error>");
}
fExtraFunctions.writeText(")");
}
// Generates a constructor for 'matrix' which reorganizes the input arguments into the proper shape.
// Keeps track of previously generated constructors so that we won't generate more than one
// constructor for any given permutation of input argument types. Returns the name of the
// generated constructor method.
std::string MetalCodeGenerator::getMatrixConstructHelper(const AnyConstructor& c) {
const Type& type = c.type();
int columns = type.columns();
int rows = type.rows();
auto args = c.argumentSpan();
std::string typeName = this->typeName(type);
// Create the helper-method name and use it as our lookup key.
std::string name = String::printf("%s_from", typeName.c_str());
for (const std::unique_ptr<Expression>& expr : args) {
String::appendf(&name, "_%s", this->typeName(expr->type()).c_str());
}
// If a helper-method has not been synthesized yet, create it now.
if (!fHelpers.contains(name)) {
fHelpers.add(name);
// Unlike GLSL, Metal requires that matrices are initialized with exactly R vectors of C
// components apiece. (In Metal 2.0, you can also supply R*C scalars, but you still cannot
// supply a mixture of scalars and vectors.)
fExtraFunctions.printf("%s %s(", typeName.c_str(), name.c_str());
size_t argIndex = 0;
const char* argSeparator = "";
for (const std::unique_ptr<Expression>& expr : args) {
fExtraFunctions.printf("%s%s x%zu", argSeparator,
this->typeName(expr->type()).c_str(), argIndex++);
argSeparator = ", ";
}
fExtraFunctions.printf(") {\n return %s(", typeName.c_str());
if (args.size() == 1 && args.front()->type().isMatrix()) {
this->assembleMatrixFromMatrix(args.front()->type(), rows, columns);
} else {
this->assembleMatrixFromExpressions(c, columns, rows);
}
fExtraFunctions.writeText(");\n}\n");
}
return name;
}
bool MetalCodeGenerator::matrixConstructHelperIsNeeded(const ConstructorCompound& c) {
SkASSERT(c.type().isMatrix());
// GLSL is fairly free-form about inputs to its matrix constructors, but Metal is not; it
// expects exactly R vectors of C components apiece. (Metal 2.0 also allows a list of R*C
// scalars.) Some cases are simple to translate and so we handle those inline--e.g. a list of
// scalars can be constructed trivially. In more complex cases, we generate a helper function
// that converts our inputs into a properly-shaped matrix.
// A matrix construct helper method is always used if any input argument is a matrix.
// Helper methods are also necessary when any argument would span multiple rows. For instance:
//
// float2 x = (1, 2);
// float3x2(x, 3, 4, 5, 6) = | 1 3 5 | = no helper needed; conversion can be done inline
// | 2 4 6 |
//
// float2 x = (2, 3);
// float3x2(1, x, 4, 5, 6) = | 1 3 5 | = x spans multiple rows; a helper method will be used
// | 2 4 6 |
//
// float4 x = (1, 2, 3, 4);
// float2x2(x) = | 1 3 | = x spans multiple rows; a helper method will be used
// | 2 4 |
//
int position = 0;
for (const std::unique_ptr<Expression>& expr : c.arguments()) {
// If an input argument is a matrix, we need a helper function.
if (expr->type().isMatrix()) {
return true;
}
position += expr->type().columns();
if (position > c.type().rows()) {
// An input argument would span multiple rows; a helper function is required.
return true;
}
if (position == c.type().rows()) {
// We've advanced to the end of a row. Wrap to the start of the next row.
position = 0;
}
}
return false;
}
void MetalCodeGenerator::writeConstructorMatrixResize(const ConstructorMatrixResize& c,
Precedence parentPrecedence) {
// Matrix-resize via casting doesn't natively exist in Metal at all, so we always need to use a
// matrix-construct helper here.
this->write(this->getMatrixConstructHelper(c));
this->write("(");
this->writeExpression(*c.argument(), Precedence::kSequence);
this->write(")");
}
void MetalCodeGenerator::writeConstructorCompound(const ConstructorCompound& c,
Precedence parentPrecedence) {
if (c.type().isVector()) {
this->writeConstructorCompoundVector(c, parentPrecedence);
} else if (c.type().isMatrix()) {
this->writeConstructorCompoundMatrix(c, parentPrecedence);
} else {
fContext.fErrors->error(c.fPosition, "unsupported compound constructor");
}
}
void MetalCodeGenerator::writeConstructorArrayCast(const ConstructorArrayCast& c,
Precedence parentPrecedence) {
const Type& inType = c.argument()->type().componentType();
const Type& outType = c.type().componentType();
std::string inTypeName = this->typeName(inType);
std::string outTypeName = this->typeName(outType);
std::string name = "array_of_" + outTypeName + "_from_" + inTypeName;
if (!fHelpers.contains(name)) {
fHelpers.add(name);
fExtraFunctions.printf(R"(
template <size_t N>
array<%s, N> %s(thread const array<%s, N>& x) {
array<%s, N> result;
for (int i = 0; i < N; ++i) {
result[i] = %s(x[i]);
}
return result;
}
)",
outTypeName.c_str(), name.c_str(), inTypeName.c_str(),
outTypeName.c_str(),
outTypeName.c_str());
}
this->write(name);
this->write("(");
this->writeExpression(*c.argument(), Precedence::kSequence);
this->write(")");
}
std::string MetalCodeGenerator::getVectorFromMat2x2ConstructorHelper(const Type& matrixType) {
SkASSERT(matrixType.isMatrix());
SkASSERT(matrixType.rows() == 2);
SkASSERT(matrixType.columns() == 2);
std::string baseType = this->typeName(matrixType.componentType());
std::string name = String::printf("%s4_from_%s2x2", baseType.c_str(), baseType.c_str());
if (!fHelpers.contains(name)) {
fHelpers.add(name);
fExtraFunctions.printf(R"(
%s4 %s(%s2x2 x) {
return %s4(x[0].xy, x[1].xy);
}
)", baseType.c_str(), name.c_str(), baseType.c_str(), baseType.c_str());
}
return name;
}
void MetalCodeGenerator::writeConstructorCompoundVector(const ConstructorCompound& c,
Precedence parentPrecedence) {
SkASSERT(c.type().isVector());
// Metal supports constructing vectors from a mix of scalars and vectors, but not matrices.
// GLSL supports vec4(mat2x2), so we detect that case here and emit a helper function.
if (c.type().columns() == 4 && c.argumentSpan().size() == 1) {
const Expression& expr = *c.argumentSpan().front();
if (expr.type().isMatrix()) {
this->write(this->getVectorFromMat2x2ConstructorHelper(expr.type()));
this->write("(");
this->writeExpression(expr, Precedence::kSequence);
this->write(")");
return;
}
}
this->writeAnyConstructor(c, "(", ")", parentPrecedence);
}
void MetalCodeGenerator::writeConstructorCompoundMatrix(const ConstructorCompound& c,
Precedence parentPrecedence) {
SkASSERT(c.type().isMatrix());
// Emit and invoke a matrix-constructor helper method if one is necessary.
if (this->matrixConstructHelperIsNeeded(c)) {
this->write(this->getMatrixConstructHelper(c));
this->write("(");
const char* separator = "";
for (const std::unique_ptr<Expression>& expr : c.arguments()) {
this->write(separator);
separator = ", ";
this->writeExpression(*expr, Precedence::kSequence);
}
this->write(")");
return;
}
// Metal doesn't allow creating matrices by passing in scalars and vectors in a jumble; it
// requires your scalars to be grouped up into columns. Because `matrixConstructHelperIsNeeded`
// returned false, we know that none of our scalars/vectors "wrap" across across a column, so we
// can group our inputs up and synthesize a constructor for each column.
const Type& matrixType = c.type();
const Type& columnType = matrixType.componentType().toCompound(
fContext, /*columns=*/matrixType.rows(), /*rows=*/1);
this->writeType(matrixType);
this->write("(");
const char* separator = "";
int scalarCount = 0;
for (const std::unique_ptr<Expression>& arg : c.arguments()) {
this->write(separator);
separator = ", ";
if (arg->type().columns() < matrixType.rows()) {
// Write a `floatN(` constructor to group scalars and smaller vectors together.
if (!scalarCount) {
this->writeType(columnType);
this->write("(");
}
scalarCount += arg->type().columns();
}
this->writeExpression(*arg, Precedence::kSequence);
if (scalarCount && scalarCount == matrixType.rows()) {
// Close our `floatN(...` constructor block from above.
this->write(")");
scalarCount = 0;
}
}
this->write(")");
}
void MetalCodeGenerator::writeAnyConstructor(const AnyConstructor& c,
const char* leftBracket,
const char* rightBracket,
Precedence parentPrecedence) {
this->writeType(c.type());
this->write(leftBracket);
const char* separator = "";
for (const std::unique_ptr<Expression>& arg : c.argumentSpan()) {
this->write(separator);
separator = ", ";
this->writeExpression(*arg, Precedence::kSequence);
}
this->write(rightBracket);
}
void MetalCodeGenerator::writeCastConstructor(const AnyConstructor& c,
const char* leftBracket,
const char* rightBracket,
Precedence parentPrecedence) {
return this->writeAnyConstructor(c, leftBracket, rightBracket, parentPrecedence);
}
void MetalCodeGenerator::writeFragCoord() {
if (!fRTFlipName.empty()) {
this->write("float4(_fragCoord.x, ");
this->write(fRTFlipName.c_str());
this->write(".x + ");
this->write(fRTFlipName.c_str());
this->write(".y * _fragCoord.y, 0.0, _fragCoord.w)");
} else {
this->write("float4(_fragCoord.x, _fragCoord.y, 0.0, _fragCoord.w)");
}
}
static bool is_compute_builtin(const Variable& var) {
switch (var.modifiers().fLayout.fBuiltin) {
case SK_NUMWORKGROUPS_BUILTIN:
case SK_WORKGROUPID_BUILTIN:
case SK_LOCALINVOCATIONID_BUILTIN:
case SK_GLOBALINVOCATIONID_BUILTIN:
case SK_LOCALINVOCATIONINDEX_BUILTIN:
return true;
default:
break;
}
return false;
}
// true if the var is part of the Inputs struct
static bool is_input(const Variable& var) {
SkASSERT(var.storage() == VariableStorage::kGlobal);
return var.modifiers().fFlags & Modifiers::kIn_Flag &&
(var.modifiers().fLayout.fBuiltin == -1 || is_compute_builtin(var)) &&
var.type().typeKind() != Type::TypeKind::kTexture;
}
// true if the var is part of the Outputs struct
static bool is_output(const Variable& var) {
SkASSERT(var.storage() == VariableStorage::kGlobal);
// inout vars get written into the Inputs struct, so we exclude them from Outputs
return (var.modifiers().fFlags & Modifiers::kOut_Flag) &&
!(var.modifiers().fFlags & Modifiers::kIn_Flag) &&
var.modifiers().fLayout.fBuiltin == -1 &&
var.type().typeKind() != Type::TypeKind::kTexture;
}
// true if the var is part of the Uniforms struct
static bool is_uniforms(const Variable& var) {
SkASSERT(var.storage() == VariableStorage::kGlobal);
return var.modifiers().fFlags & Modifiers::kUniform_Flag &&
var.type().typeKind() != Type::TypeKind::kSampler;
}
// true if the var is part of the Threadgroups struct
static bool is_threadgroup(const Variable& var) {
SkASSERT(var.storage() == VariableStorage::kGlobal);
return var.modifiers().fFlags & Modifiers::kWorkgroup_Flag;
}
// true if the var is part of the Globals struct
static bool is_in_globals(const Variable& var) {
SkASSERT(var.storage() == VariableStorage::kGlobal);
return !(var.modifiers().fFlags & Modifiers::kConst_Flag);
}
void MetalCodeGenerator::writeVariableReference(const VariableReference& ref) {
// When assembling out-param helper functions, we copy variables into local clones with matching
// names. We never want to prepend "_in." or "_globals." when writing these variables since
// we're actually targeting the clones.
if (fIgnoreVariableReferenceModifiers) {
this->writeName(ref.variable()->mangledName());
return;
}
switch (ref.variable()->modifiers().fLayout.fBuiltin) {
case SK_FRAGCOLOR_BUILTIN:
this->write("_out.sk_FragColor");
break;
case SK_FRAGCOORD_BUILTIN:
this->writeFragCoord();
break;
case SK_VERTEXID_BUILTIN:
this->write("sk_VertexID");
break;
case SK_INSTANCEID_BUILTIN:
this->write("sk_InstanceID");
break;
case SK_CLOCKWISE_BUILTIN:
// We'd set the front facing winding in the MTLRenderCommandEncoder to be counter
// clockwise to match Skia convention.
if (!fRTFlipName.empty()) {
this->write("(" + fRTFlipName + ".y < 0 ? _frontFacing : !_frontFacing)");
} else {
this->write("_frontFacing");
}
break;
default:
const Variable& var = *ref.variable();
if (var.storage() == Variable::Storage::kGlobal) {
if (is_input(var)) {
this->write("_in.");
} else if (is_output(var)) {
this->write("_out.");
} else if (is_uniforms(var)) {
this->write("_uniforms.");
} else if (is_threadgroup(var)) {
this->write("_threadgroups.");
} else if (is_in_globals(var)) {
this->write("_globals.");
}
}
this->writeName(var.mangledName());
}
}
void MetalCodeGenerator::writeIndexExpression(const IndexExpression& expr) {
this->writeExpression(*expr.base(), Precedence::kPostfix);
this->write("[");
this->writeExpression(*expr.index(), Precedence::kTopLevel);
this->write("]");
}
void MetalCodeGenerator::writeFieldAccess(const FieldAccess& f) {
const Type::Field* field = &f.base()->type().fields()[f.fieldIndex()];
if (FieldAccess::OwnerKind::kDefault == f.ownerKind()) {
this->writeExpression(*f.base(), Precedence::kPostfix);
this->write(".");
}
switch (field->fModifiers.fLayout.fBuiltin) {
case SK_POSITION_BUILTIN:
this->write("_out.sk_Position");
break;
case SK_POINTSIZE_BUILTIN:
this->write("_out.sk_PointSize");
break;
default:
if (FieldAccess::OwnerKind::kAnonymousInterfaceBlock == f.ownerKind()) {
this->write("_globals.");
this->write(fInterfaceBlockNameMap[fInterfaceBlockMap[field]]);
this->write("->");
}
this->writeName(field->fName);
}
}
void MetalCodeGenerator::writeSwizzle(const Swizzle& swizzle) {
this->writeExpression(*swizzle.base(), Precedence::kPostfix);
this->write(".");
for (int c : swizzle.components()) {
SkASSERT(c >= 0 && c <= 3);
this->write(&("x\0y\0z\0w\0"[c * 2]));
}
}
void MetalCodeGenerator::writeMatrixTimesEqualHelper(const Type& left, const Type& right,
const Type& result) {
SkASSERT(left.isMatrix());
SkASSERT(right.isMatrix());
SkASSERT(result.isMatrix());
std::string key = "Matrix *= " + this->typeName(left) + ":" + this->typeName(right);
if (!fHelpers.contains(key)) {
fHelpers.add(key);
fExtraFunctions.printf("thread %s& operator*=(thread %s& left, thread const %s& right) {\n"
" left = left * right;\n"
" return left;\n"
"}\n",
this->typeName(result).c_str(), this->typeName(left).c_str(),
this->typeName(right).c_str());
}
}
void MetalCodeGenerator::writeMatrixEqualityHelpers(const Type& left, const Type& right) {
SkASSERT(left.isMatrix());
SkASSERT(right.isMatrix());
SkASSERT(left.rows() == right.rows());
SkASSERT(left.columns() == right.columns());
std::string key = "Matrix == " + this->typeName(left) + ":" + this->typeName(right);
if (!fHelpers.contains(key)) {
fHelpers.add(key);
fExtraFunctionPrototypes.printf(R"(
thread bool operator==(const %s left, const %s right);
thread bool operator!=(const %s left, const %s right);
)",
this->typeName(left).c_str(),
this->typeName(right).c_str(),
this->typeName(left).c_str(),
this->typeName(right).c_str());
fExtraFunctions.printf(
"thread bool operator==(const %s left, const %s right) {\n"
" return ",
this->typeName(left).c_str(), this->typeName(right).c_str());
const char* separator = "";
for (int index=0; index<left.columns(); ++index) {
fExtraFunctions.printf("%sall(left[%d] == right[%d])", separator, index, index);
separator = " &&\n ";
}
fExtraFunctions.printf(
";\n"
"}\n"
"thread bool operator!=(const %s left, const %s right) {\n"
" return !(left == right);\n"
"}\n",
this->typeName(left).c_str(), this->typeName(right).c_str());
}
}
void MetalCodeGenerator::writeMatrixDivisionHelpers(const Type& type) {
SkASSERT(type.isMatrix());
std::string key = "Matrix / " + this->typeName(type);
if (!fHelpers.contains(key)) {
fHelpers.add(key);
std::string typeName = this->typeName(type);
fExtraFunctions.printf(
"thread %s operator/(const %s left, const %s right) {\n"
" return %s(",
typeName.c_str(), typeName.c_str(), typeName.c_str(), typeName.c_str());
const char* separator = "";
for (int index=0; index<type.columns(); ++index) {
fExtraFunctions.printf("%sleft[%d] / right[%d]", separator, index, index);
separator = ", ";
}
fExtraFunctions.printf(");\n"
"}\n"
"thread %s& operator/=(thread %s& left, thread const %s& right) {\n"
" left = left / right;\n"
" return left;\n"
"}\n",
typeName.c_str(), typeName.c_str(), typeName.c_str());
}
}
void MetalCodeGenerator::writeArrayEqualityHelpers(const Type& type) {
SkASSERT(type.isArray());
// If the array's component type needs a helper as well, we need to emit that one first.
this->writeEqualityHelpers(type.componentType(), type.componentType());
std::string key = "ArrayEquality []";
if (!fHelpers.contains(key)) {
fHelpers.add(key);
fExtraFunctionPrototypes.writeText(R"(
template <typename T1, typename T2>
bool operator==(const array_ref<T1> left, const array_ref<T2> right);
template <typename T1, typename T2>
bool operator!=(const array_ref<T1> left, const array_ref<T2> right);
)");
fExtraFunctions.writeText(R"(
template <typename T1, typename T2>
bool operator==(const array_ref<T1> left, const array_ref<T2> right) {
if (left.size() != right.size()) {
return false;
}
for (size_t index = 0; index < left.size(); ++index) {
if (!all(left[index] == right[index])) {
return false;
}
}
return true;
}
template <typename T1, typename T2>
bool operator!=(const array_ref<T1> left, const array_ref<T2> right) {
return !(left == right);
}
)");
}
}
void MetalCodeGenerator::writeStructEqualityHelpers(const Type& type) {
SkASSERT(type.isStruct());
std::string key = "StructEquality " + this->typeName(type);
if (!fHelpers.contains(key)) {
fHelpers.add(key);
// If one of the struct's fields needs a helper as well, we need to emit that one first.
for (const Type::Field& field : type.fields()) {
this->writeEqualityHelpers(*field.fType, *field.fType);
}
// Write operator== and operator!= for this struct, since those are assumed to exist in SkSL
// and GLSL but do not exist by default in Metal.
fExtraFunctionPrototypes.printf(R"(
thread bool operator==(thread const %s& left, thread const %s& right);
thread bool operator!=(thread const %s& left, thread const %s& right);
)",
this->typeName(type).c_str(),
this->typeName(type).c_str(),
this->typeName(type).c_str(),
this->typeName(type).c_str());
fExtraFunctions.printf(
"thread bool operator==(thread const %s& left, thread const %s& right) {\n"
" return ",
this->typeName(type).c_str(),
this->typeName(type).c_str());
const char* separator = "";
for (const Type::Field& field : type.fields()) {
if (field.fType->isArray()) {
fExtraFunctions.printf(
"%s(make_array_ref(left.%.*s) == make_array_ref(right.%.*s))",
separator,
(int)field.fName.size(), field.fName.data(),
(int)field.fName.size(), field.fName.data());
} else {
fExtraFunctions.printf("%sall(left.%.*s == right.%.*s)",
separator,
(int)field.fName.size(), field.fName.data(),
(int)field.fName.size(), field.fName.data());
}
separator = " &&\n ";
}
fExtraFunctions.printf(
";\n"
"}\n"
"thread bool operator!=(thread const %s& left, thread const %s& right) {\n"
" return !(left == right);\n"
"}\n",
this->typeName(type).c_str(),
this->typeName(type).c_str());
}
}
void MetalCodeGenerator::writeEqualityHelpers(const Type& leftType, const Type& rightType) {
if (leftType.isArray() && rightType.isArray()) {
this->writeArrayEqualityHelpers(leftType);
return;
}
if (leftType.isStruct() && rightType.isStruct()) {
this->writeStructEqualityHelpers(leftType);
return;
}
if (leftType.isMatrix() && rightType.isMatrix()) {
this->writeMatrixEqualityHelpers(leftType, rightType);
return;
}
}
void MetalCodeGenerator::writeNumberAsMatrix(const Expression& expr, const Type& matrixType) {
SkASSERT(expr.type().isNumber());
SkASSERT(matrixType.isMatrix());
// Componentwise multiply the scalar against a matrix of the desired size which contains all 1s.
this->write("(");
this->writeType(matrixType);
this->write("(");
const char* separator = "";
for (int index = matrixType.slotCount(); index--;) {
this->write(separator);
this->write("1.0");
separator = ", ";
}
this->write(") * ");
this->writeExpression(expr, Precedence::kMultiplicative);
this->write(")");
}
void MetalCodeGenerator::writeBinaryExpression(const BinaryExpression& b,
Precedence parentPrecedence) {
const Expression& left = *b.left();
const Expression& right = *b.right();
const Type& leftType = left.type();
const Type& rightType = right.type();
Operator op = b.getOperator();
Precedence precedence = op.getBinaryPrecedence();
bool needParens = precedence >= parentPrecedence;
switch (op.kind()) {
case Operator::Kind::EQEQ:
this->writeEqualityHelpers(leftType, rightType);
if (leftType.isVector()) {
this->write("all");
needParens = true;
}
break;
case Operator::Kind::NEQ:
this->writeEqualityHelpers(leftType, rightType);
if (leftType.isVector()) {
this->write("any");
needParens = true;
}
break;
default:
break;
}
if (leftType.isMatrix() && rightType.isMatrix() && op.kind() == Operator::Kind::STAREQ) {
this->writeMatrixTimesEqualHelper(leftType, rightType, b.type());
}
if (op.removeAssignment().kind() == Operator::Kind::SLASH &&
((leftType.isMatrix() && rightType.isMatrix()) ||
(leftType.isScalar() && rightType.isMatrix()) ||
(leftType.isMatrix() && rightType.isScalar()))) {
this->writeMatrixDivisionHelpers(leftType.isMatrix() ? leftType : rightType);
}
if (needParens) {
this->write("(");
}
bool needMatrixSplatOnScalar = rightType.isMatrix() && leftType.isNumber() &&
op.isValidForMatrixOrVector() &&
op.removeAssignment().kind() != Operator::Kind::STAR;
if (needMatrixSplatOnScalar) {
this->writeNumberAsMatrix(left, rightType);
} else if (op.isEquality() && leftType.isArray()) {
this->write("make_array_ref(");
this->writeExpression(left, precedence);
this->write(")");
} else {
this->writeExpression(left, precedence);
}
if (op.kind() != Operator::Kind::EQ && op.isAssignment() &&
left.kind() == Expression::Kind::kSwizzle && !Analysis::HasSideEffects(left)) {
// This doesn't compile in Metal:
// float4 x = float4(1);
// x.xy *= float2x2(...);
// with the error message "non-const reference cannot bind to vector element",
// but switching it to x.xy = x.xy * float2x2(...) fixes it. We perform this tranformation
// as long as the LHS has no side effects, and hope for the best otherwise.
this->write(" = ");
this->writeExpression(left, Precedence::kAssignment);
this->write(operator_name(op.removeAssignment()));
} else {
this->write(operator_name(op));
}
needMatrixSplatOnScalar = leftType.isMatrix() && rightType.isNumber() &&
op.isValidForMatrixOrVector() &&
op.removeAssignment().kind() != Operator::Kind::STAR;
if (needMatrixSplatOnScalar) {
this->writeNumberAsMatrix(right, leftType);
} else if (op.isEquality() && rightType.isArray()) {
this->write("make_array_ref(");
this->writeExpression(right, precedence);
this->write(")");
} else {
this->writeExpression(right, precedence);
}
if (needParens) {
this->write(")");
}
}
void MetalCodeGenerator::writeTernaryExpression(const TernaryExpression& t,
Precedence parentPrecedence) {
if (Precedence::kTernary >= parentPrecedence) {
this->write("(");
}
this->writeExpression(*t.test(), Precedence::kTernary);
this->write(" ? ");
this->writeExpression(*t.ifTrue(), Precedence::kTernary);
this->write(" : ");
this->writeExpression(*t.ifFalse(), Precedence::kTernary);
if (Precedence::kTernary >= parentPrecedence) {
this->write(")");
}
}
void MetalCodeGenerator::writePrefixExpression(const PrefixExpression& p,
Precedence parentPrecedence) {
// According to the MSL specification, the arithmetic unary operators (+ and –) do not act
// upon matrix type operands. We treat the unary "+" as NOP for all operands.
const Operator op = p.getOperator();
if (op.kind() == Operator::Kind::PLUS) {
return this->writeExpression(*p.operand(), Precedence::kPrefix);
}
const bool matrixNegation =
op.kind() == Operator::Kind::MINUS && p.operand()->type().isMatrix();
const bool needParens = Precedence::kPrefix >= parentPrecedence || matrixNegation;
if (needParens) {
this->write("(");
}
// Transform the unary "-" on a matrix type to a multiplication by -1.
if (matrixNegation) {
this->write("-1.0 * ");
} else {
this->write(p.getOperator().tightOperatorName());
}
this->writeExpression(*p.operand(), Precedence::kPrefix);
if (needParens) {
this->write(")");
}
}
void MetalCodeGenerator::writePostfixExpression(const PostfixExpression& p,
Precedence parentPrecedence) {
if (Precedence::kPostfix >= parentPrecedence) {
this->write("(");
}
this->writeExpression(*p.operand(), Precedence::kPostfix);
this->write(p.getOperator().tightOperatorName());
if (Precedence::kPostfix >= parentPrecedence) {
this->write(")");
}
}
void MetalCodeGenerator::writeLiteral(const Literal& l) {
const Type& type = l.type();
if (type.isFloat()) {
this->write(l.description(OperatorPrecedence::kTopLevel));
if (!l.type().highPrecision()) {
this->write("h");
}
return;
}
if (type.isInteger()) {
if (type.matches(*fContext.fTypes.fUInt)) {
this->write(std::to_string(l.intValue() & 0xffffffff));
this->write("u");
} else if (type.matches(*fContext.fTypes.fUShort)) {
this->write(std::to_string(l.intValue() & 0xffff));
this->write("u");
} else {
this->write(std::to_string(l.intValue()));
}
return;
}
SkASSERT(type.isBoolean());
this->write(l.description(OperatorPrecedence::kTopLevel));
}
void MetalCodeGenerator::writeFunctionRequirementArgs(const FunctionDeclaration& f,
const char*& separator) {
Requirements requirements = this->requirements(f);
if (requirements & kInputs_Requirement) {
this->write(separator);
this->write("_in");
separator = ", ";
}
if (requirements & kOutputs_Requirement) {
this->write(separator);
this->write("_out");
separator = ", ";
}
if (requirements & kUniforms_Requirement) {
this->write(separator);
this->write("_uniforms");
separator = ", ";
}
if (requirements & kGlobals_Requirement) {
this->write(separator);
this->write("_globals");
separator = ", ";
}
if (requirements & kFragCoord_Requirement) {
this->write(separator);
this->write("_fragCoord");
separator = ", ";
}
if (requirements & kThreadgroups_Requirement) {
this->write(separator);
this->write("_threadgroups");
separator = ", ";
}
}
void MetalCodeGenerator::writeFunctionRequirementParams(const FunctionDeclaration& f,
const char*& separator) {
Requirements requirements = this->requirements(f);
if (requirements & kInputs_Requirement) {
this->write(separator);
this->write("Inputs _in");
separator = ", ";
}
if (requirements & kOutputs_Requirement) {
this->write(separator);
this->write("thread Outputs& _out");
separator = ", ";
}
if (requirements & kUniforms_Requirement) {
this->write(separator);
this->write("Uniforms _uniforms");
separator = ", ";
}
if (requirements & kGlobals_Requirement) {
this->write(separator);
this->write("thread Globals& _globals");
separator = ", ";
}
if (requirements & kFragCoord_Requirement) {
this->write(separator);
this->write("float4 _fragCoord");
separator = ", ";
}
if (requirements & kThreadgroups_Requirement) {
this->write(separator);
this->write("threadgroup Threadgroups& _threadgroups");
separator = ", ";
}
}
int MetalCodeGenerator::getUniformBinding(const Modifiers& m) {
return (m.fLayout.fBinding >= 0) ? m.fLayout.fBinding
: fProgram.fConfig->fSettings.fDefaultUniformBinding;
}
int MetalCodeGenerator::getUniformSet(const Modifiers& m) {
return (m.fLayout.fSet >= 0) ? m.fLayout.fSet
: fProgram.fConfig->fSettings.fDefaultUniformSet;
}
bool MetalCodeGenerator::writeFunctionDeclaration(const FunctionDeclaration& f) {
fRTFlipName = fProgram.fInputs.fUseFlipRTUniform
? "_globals._anonInterface0->" SKSL_RTFLIP_NAME
: "";
const char* separator = "";
if (f.isMain()) {
if (ProgramConfig::IsFragment(fProgram.fConfig->fKind)) {
this->write("fragment Outputs fragmentMain");
} else if (ProgramConfig::IsVertex(fProgram.fConfig->fKind)) {
this->write("vertex Outputs vertexMain");
} else if (ProgramConfig::IsCompute(fProgram.fConfig->fKind)) {
this->write("kernel void computeMain");
} else {
fContext.fErrors->error(Position(), "unsupported kind of program");
return false;
}
this->write("(");
if (!ProgramConfig::IsCompute(fProgram.fConfig->fKind)) {
this->write("Inputs _in [[stage_in]]");
separator = ", ";
}
if (-1 != fUniformBuffer) {
this->write(separator);
this->write("constant Uniforms& _uniforms [[buffer(" +
std::to_string(fUniformBuffer) + ")]]");
separator = ", ";
}
for (const ProgramElement* e : fProgram.elements()) {
if (e->is<GlobalVarDeclaration>()) {
const GlobalVarDeclaration& decls = e->as<GlobalVarDeclaration>();
const VarDeclaration& decl = decls.varDeclaration();
const Variable* var = decl.var();
const SkSL::Type::TypeKind varKind = var->type().typeKind();
if (varKind == Type::TypeKind::kSampler || varKind == Type::TypeKind::kTexture) {
if (var->type().dimensions() != SpvDim2D) {
// Not yet implemented--Skia currently only uses 2D textures.
fContext.fErrors->error(decls.fPosition, "Unsupported texture dimensions");
return false;
}
int binding = getUniformBinding(var->modifiers());
this->write(separator);
separator = ", ";
if (varKind == Type::TypeKind::kSampler) {
this->writeType(var->type().textureType());
this->write(" ");
this->writeName(var->mangledName());
this->write(kTextureSuffix);
this->write(" [[texture(");
this->write(std::to_string(binding));
this->write(")]], sampler ");
this->writeName(var->mangledName());
this->write(kSamplerSuffix);
this->write(" [[sampler(");
this->write(std::to_string(binding));
this->write(")]]");
} else {
SkASSERT(varKind == Type::TypeKind::kTexture);
this->writeType(var->type());
this->write(" ");
this->writeName(var->mangledName());
this->write(" [[texture(");
this->write(std::to_string(binding));
this->write(")]]");
}
} else if (ProgramConfig::IsCompute(fProgram.fConfig->fKind)) {
std::string type, attr;
switch (var->modifiers().fLayout.fBuiltin) {
case SK_NUMWORKGROUPS_BUILTIN:
type = "uint3 ";
attr = " [[threadgroups_per_grid]]";
break;
case SK_WORKGROUPID_BUILTIN:
type = "uint3 ";
attr = " [[threadgroup_position_in_grid]]";
break;
case SK_LOCALINVOCATIONID_BUILTIN:
type = "uint3 ";
attr = " [[thread_position_in_threadgroup]]";
break;
case SK_GLOBALINVOCATIONID_BUILTIN:
type = "uint3 ";
attr = " [[thread_position_in_grid]]";
break;
case SK_LOCALINVOCATIONINDEX_BUILTIN:
type = "uint ";
attr = " [[thread_index_in_threadgroup]]";
break;
default:
break;
}
if (!attr.empty()) {
this->write(separator);
this->write(type);
this->write(var->name());
this->write(attr);
separator = ", ";
}
}
} else if (e->is<InterfaceBlock>()) {
const InterfaceBlock& intf = e->as<InterfaceBlock>();
if (intf.typeName() == "sk_PerVertex") {
continue;
}
this->write(separator);
if (is_readonly(intf)) {
this->write("const ");
}
this->write(is_buffer(intf) ? "device " : "constant ");
this->writeType(intf.var()->type());
this->write("& " );
this->write(fInterfaceBlockNameMap[&intf]);
this->write(" [[buffer(");
this->write(std::to_string(this->getUniformBinding(intf.var()->modifiers())));
this->write(")]]");
separator = ", ";
}
}
if (ProgramConfig::IsFragment(fProgram.fConfig->fKind)) {
if (fProgram.fInputs.fUseFlipRTUniform && fInterfaceBlockNameMap.empty()) {
this->write(separator);
this->write("constant sksl_synthetic_uniforms& _anonInterface0 [[buffer(1)]]");
fRTFlipName = "_anonInterface0." SKSL_RTFLIP_NAME;
separator = ", ";
}
this->write(separator);
this->write("bool _frontFacing [[front_facing]]");
this->write(", float4 _fragCoord [[position]]");
separator = ", ";
} else if (ProgramConfig::IsVertex(fProgram.fConfig->fKind)) {
this->write(separator);
this->write("uint sk_VertexID [[vertex_id]], uint sk_InstanceID [[instance_id]]");
separator = ", ";
}
} else {
this->writeType(f.returnType());
this->write(" ");
this->writeName(f.mangledName());
this->write("(");
this->writeFunctionRequirementParams(f, separator);
}
for (const Variable* param : f.parameters()) {
if (f.isMain() && param->modifiers().fLayout.fBuiltin != -1) {
continue;
}
this->write(separator);
separator = ", ";
this->writeModifiers(param->modifiers());
this->writeType(param->type());
if (pass_by_reference(param->type(), param->modifiers())) {
this->write("&");
}
this->write(" ");
this->writeName(param->mangledName());
}
this->write(")");
return true;
}
void MetalCodeGenerator::writeFunctionPrototype(const FunctionPrototype& f) {
this->writeFunctionDeclaration(f.declaration());
this->writeLine(";");
}
static bool is_block_ending_with_return(const Statement* stmt) {
// This function detects (potentially nested) blocks that end in a return statement.
if (!stmt->is<Block>()) {
return false;
}
const StatementArray& block = stmt->as<Block>().children();
for (int index = block.size(); index--; ) {
stmt = block[index].get();
if (stmt->is<ReturnStatement>()) {
return true;
}
if (stmt->is<Block>()) {
return is_block_ending_with_return(stmt);
}
if (!stmt->is<Nop>()) {
break;
}
}
return false;
}
void MetalCodeGenerator::writeComputeMainInputs() {
// Compute shaders only have input variables (e.g. sk_GlobalInvocationID) and access program
// inputs/outputs via the Globals and Uniforms structs. We collect the allowed "in" parameters
// into an Input struct here, since the rest of the code expects the normal _in / _out pattern.
this->write("Inputs _in = { ");
const char* separator = "";
for (const ProgramElement* e : fProgram.elements()) {
if (e->is<GlobalVarDeclaration>()) {
const GlobalVarDeclaration& decls = e->as<GlobalVarDeclaration>();
const Variable* var = decls.varDeclaration().var();
if (is_input(*var)) {
this->write(separator);
separator = ", ";
this->writeName(var->mangledName());
}
}
}
this->writeLine(" };");
}
void MetalCodeGenerator::writeFunction(const FunctionDefinition& f) {
SkASSERT(!fProgram.fConfig->fSettings.fFragColorIsInOut);
if (!this->writeFunctionDeclaration(f.declaration())) {
return;
}
fCurrentFunction = &f.declaration();
SkScopeExit clearCurrentFunction([&] { fCurrentFunction = nullptr; });
this->writeLine(" {");
if (f.declaration().isMain()) {
fIndentation++;
this->writeGlobalInit();
if (ProgramConfig::IsCompute(fProgram.fConfig->fKind)) {
this->writeThreadgroupInit();
this->writeComputeMainInputs();
}
else {
this->writeLine("Outputs _out;");
this->writeLine("(void)_out;");
}
fIndentation--;
}
fFunctionHeader.clear();
StringStream buffer;
{
AutoOutputStream outputToBuffer(this, &buffer);
fIndentation++;
for (const std::unique_ptr<Statement>& stmt : f.body()->as<Block>().children()) {
if (!stmt->isEmpty()) {
this->writeStatement(*stmt);
this->finishLine();
}
}
if (f.declaration().isMain()) {
// If the main function doesn't end with a return, we need to synthesize one here.
if (!is_block_ending_with_return(f.body().get())) {
this->writeReturnStatementFromMain();
this->finishLine();
}
}
fIndentation--;
this->writeLine("}");
}
this->write(fFunctionHeader);
this->write(buffer.str());
}
void MetalCodeGenerator::writeModifiers(const Modifiers& modifiers) {
if (ProgramConfig::IsCompute(fProgram.fConfig->fKind) &&
(modifiers.fFlags & (Modifiers::kIn_Flag | Modifiers::kOut_Flag))) {
this->write("device ");
} else if (modifiers.fFlags & Modifiers::kOut_Flag) {
this->write("thread ");
}
if (modifiers.fFlags & Modifiers::kConst_Flag) {
this->write("const ");
}
}
void MetalCodeGenerator::writeInterfaceBlock(const InterfaceBlock& intf) {
if (intf.typeName() == "sk_PerVertex") {
return;
}
const Type* structType = &intf.var()->type().componentType();
this->writeModifiers(intf.var()->modifiers());
this->write("struct ");
this->writeType(*structType);
this->writeLine(" {");
fIndentation++;
this->writeFields(structType->fields(), structType->fPosition, &intf);
if (fProgram.fInputs.fUseFlipRTUniform) {
this->writeLine("float2 " SKSL_RTFLIP_NAME ";");
}
fIndentation--;
this->write("}");
if (intf.instanceName().size()) {
this->write(" ");
this->write(intf.instanceName());
if (intf.arraySize() > 0) {
this->write("[");
this->write(std::to_string(intf.arraySize()));
this->write("]");
}
fInterfaceBlockNameMap.set(&intf, intf.instanceName());
} else {
fInterfaceBlockNameMap.set(&intf, *fProgram.fSymbols->takeOwnershipOfString(
"_anonInterface" + std::to_string(fAnonInterfaceCount++)));
}
this->writeLine(";");
}
void MetalCodeGenerator::writeFields(const std::vector<Type::Field>& fields, Position parentPos,
const InterfaceBlock* parentIntf) {
MemoryLayout memoryLayout(MemoryLayout::Standard::kMetal);
int currentOffset = 0;
for (const Type::Field& field : fields) {
int fieldOffset = field.fModifiers.fLayout.fOffset;
const Type* fieldType = field.fType;
if (!memoryLayout.isSupported(*fieldType)) {
fContext.fErrors->error(parentPos, "type '" + std::string(fieldType->name()) +
"' is not permitted here");
return;
}
if (fieldOffset != -1) {
if (currentOffset > fieldOffset) {
fContext.fErrors->error(field.fPosition,
"offset of field '" + std::string(field.fName) +
"' must be at least " + std::to_string(currentOffset));
return;
} else if (currentOffset < fieldOffset) {
this->write("char pad");
this->write(std::to_string(fPaddingCount++));
this->write("[");
this->write(std::to_string(fieldOffset - currentOffset));
this->writeLine("];");
currentOffset = fieldOffset;
}
int alignment = memoryLayout.alignment(*fieldType);
if (fieldOffset % alignment) {
fContext.fErrors->error(field.fPosition,
"offset of field '" + std::string(field.fName) +
"' must be a multiple of " + std::to_string(alignment));
return;
}
}
if (fieldType->isUnsizedArray()) {
// An unsized array always appears as the last member of a storage block. We declare
// it as a one-element array and allow dereferencing past the capacity.
// TODO(armansito): This is because C++ does not support flexible array members like C99
// does. This generally works but it can lead to UB as compilers are free to insert
// padding past the first element of the array. An alternative approach is to declare
// the struct without the unsized array member and replace variable references with a
// buffer offset calculation based on sizeof().
this->writeModifiers(field.fModifiers);
this->writeType(fieldType->componentType());
this->write(" ");
this->writeName(field.fName);
this->write("[1]");
} else {
size_t fieldSize = memoryLayout.size(*fieldType);
if (fieldSize > static_cast<size_t>(std::numeric_limits<int>::max() - currentOffset)) {
fContext.fErrors->error(parentPos, "field offset overflow");
return;
}
currentOffset += fieldSize;
this->writeModifiers(field.fModifiers);
this->writeType(*fieldType);
this->write(" ");
this->writeName(field.fName);
}
this->writeLine(";");
if (parentIntf) {
fInterfaceBlockMap.set(&field, parentIntf);
}
}
}
void MetalCodeGenerator::writeVarInitializer(const Variable& var, const Expression& value) {
this->writeExpression(value, Precedence::kTopLevel);
}
void MetalCodeGenerator::writeName(std::string_view name) {
if (fReservedWords.contains(name)) {
this->write("_"); // adding underscore before name to avoid conflict with reserved words
}
this->write(name);
}
void MetalCodeGenerator::writeVarDeclaration(const VarDeclaration& varDecl) {
this->writeModifiers(varDecl.var()->modifiers());
this->writeType(varDecl.var()->type());
this->write(" ");
this->writeName(varDecl.var()->mangledName());
if (varDecl.value()) {
this->write(" = ");
this->writeVarInitializer(*varDecl.var(), *varDecl.value());
}
this->write(";");
}
void MetalCodeGenerator::writeStatement(const Statement& s) {
switch (s.kind()) {
case Statement::Kind::kBlock:
this->writeBlock(s.as<Block>());
break;
case Statement::Kind::kExpression:
this->writeExpressionStatement(s.as<ExpressionStatement>());
break;
case Statement::Kind::kReturn:
this->writeReturnStatement(s.as<ReturnStatement>());
break;
case Statement::Kind::kVarDeclaration:
this->writeVarDeclaration(s.as<VarDeclaration>());
break;
case Statement::Kind::kIf:
this->writeIfStatement(s.as<IfStatement>());
break;
case Statement::Kind::kFor:
this->writeForStatement(s.as<ForStatement>());
break;
case Statement::Kind::kDo:
this->writeDoStatement(s.as<DoStatement>());
break;
case Statement::Kind::kSwitch:
this->writeSwitchStatement(s.as<SwitchStatement>());
break;
case Statement::Kind::kBreak:
this->write("break;");
break;
case Statement::Kind::kContinue:
this->write("continue;");
break;
case Statement::Kind::kDiscard:
this->write("discard_fragment();");
break;
case Statement::Kind::kNop:
this->write(";");
break;
default:
SkDEBUGFAILF("unsupported statement: %s", s.description().c_str());
break;
}
}
void MetalCodeGenerator::writeBlock(const Block& b) {
// Write scope markers if this block is a scope, or if the block is empty (since we need to emit
// something here to make the code valid).
bool isScope = b.isScope() || b.isEmpty();
if (isScope) {
this->writeLine("{");
fIndentation++;
}
for (const std::unique_ptr<Statement>& stmt : b.children()) {
if (!stmt->isEmpty()) {
this->writeStatement(*stmt);
this->finishLine();
}
}
if (isScope) {
fIndentation--;
this->write("}");
}
}
void MetalCodeGenerator::writeIfStatement(const IfStatement& stmt) {
this->write("if (");
this->writeExpression(*stmt.test(), Precedence::kTopLevel);
this->write(") ");
this->writeStatement(*stmt.ifTrue());
if (stmt.ifFalse()) {
this->write(" else ");
this->writeStatement(*stmt.ifFalse());
}
}
void MetalCodeGenerator::writeForStatement(const ForStatement& f) {
// Emit loops of the form 'for(;test;)' as 'while(test)', which is probably how they started
if (!f.initializer() && f.test() && !f.next()) {
this->write("while (");
this->writeExpression(*f.test(), Precedence::kTopLevel);
this->write(") ");
this->writeStatement(*f.statement());
return;
}
this->write("for (");
if (f.initializer() && !f.initializer()->isEmpty()) {
this->writeStatement(*f.initializer());
} else {
this->write("; ");
}
if (f.test()) {
this->writeExpression(*f.test(), Precedence::kTopLevel);
}
this->write("; ");
if (f.next()) {
this->writeExpression(*f.next(), Precedence::kTopLevel);
}
this->write(") ");
this->writeStatement(*f.statement());
}
void MetalCodeGenerator::writeDoStatement(const DoStatement& d) {
this->write("do ");
this->writeStatement(*d.statement());
this->write(" while (");
this->writeExpression(*d.test(), Precedence::kTopLevel);
this->write(");");
}
void MetalCodeGenerator::writeExpressionStatement(const ExpressionStatement& s) {
if (fProgram.fConfig->fSettings.fOptimize && !Analysis::HasSideEffects(*s.expression())) {
// Don't emit dead expressions.
return;
}
this->writeExpression(*s.expression(), Precedence::kTopLevel);
this->write(";");
}
void MetalCodeGenerator::writeSwitchStatement(const SwitchStatement& s) {
this->write("switch (");
this->writeExpression(*s.value(), Precedence::kTopLevel);
this->writeLine(") {");
fIndentation++;
for (const std::unique_ptr<Statement>& stmt : s.cases()) {
const SwitchCase& c = stmt->as<SwitchCase>();
if (c.isDefault()) {
this->writeLine("default:");
} else {
this->write("case ");
this->write(std::to_string(c.value()));
this->writeLine(":");
}
if (!c.statement()->isEmpty()) {
fIndentation++;
this->writeStatement(*c.statement());
this->finishLine();
fIndentation--;
}
}
fIndentation--;
this->write("}");
}
void MetalCodeGenerator::writeReturnStatementFromMain() {
// main functions in Metal return a magic _out parameter that doesn't exist in SkSL.
if (ProgramConfig::IsVertex(fProgram.fConfig->fKind) ||
ProgramConfig::IsFragment(fProgram.fConfig->fKind)) {
this->write("return _out;");
} else if (ProgramConfig::IsCompute(fProgram.fConfig->fKind)) {
this->write("return;");
} else {
SkDEBUGFAIL("unsupported kind of program");
}
}
void MetalCodeGenerator::writeReturnStatement(const ReturnStatement& r) {
if (fCurrentFunction && fCurrentFunction->isMain()) {
if (r.expression()) {
if (r.expression()->type().matches(*fContext.fTypes.fHalf4)) {
this->write("_out.sk_FragColor = ");
this->writeExpression(*r.expression(), Precedence::kTopLevel);
this->writeLine(