| /* |
| * Copyright 2020 Google LLC |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #include "src/sksl/SkSLInliner.h" |
| |
| #ifndef SK_ENABLE_OPTIMIZE_SIZE |
| |
| #include "include/core/SkSpan.h" |
| #include "include/core/SkTypes.h" |
| #include "include/private/SkSLDefines.h" |
| #include "include/private/SkSLIRNode.h" |
| #include "include/private/SkSLModifiers.h" |
| #include "include/private/SkSLProgramElement.h" |
| #include "include/private/SkSLStatement.h" |
| #include "include/private/base/SkTArray.h" |
| #include "include/sksl/SkSLErrorReporter.h" |
| #include "include/sksl/SkSLOperator.h" |
| #include "include/sksl/SkSLPosition.h" |
| #include "src/sksl/SkSLAnalysis.h" |
| #include "src/sksl/analysis/SkSLProgramUsage.h" |
| #include "src/sksl/ir/SkSLBinaryExpression.h" |
| #include "src/sksl/ir/SkSLChildCall.h" |
| #include "src/sksl/ir/SkSLConstructor.h" |
| #include "src/sksl/ir/SkSLConstructorArray.h" |
| #include "src/sksl/ir/SkSLConstructorArrayCast.h" |
| #include "src/sksl/ir/SkSLConstructorCompound.h" |
| #include "src/sksl/ir/SkSLConstructorCompoundCast.h" |
| #include "src/sksl/ir/SkSLConstructorDiagonalMatrix.h" |
| #include "src/sksl/ir/SkSLConstructorMatrixResize.h" |
| #include "src/sksl/ir/SkSLConstructorScalarCast.h" |
| #include "src/sksl/ir/SkSLConstructorSplat.h" |
| #include "src/sksl/ir/SkSLConstructorStruct.h" |
| #include "src/sksl/ir/SkSLDoStatement.h" |
| #include "src/sksl/ir/SkSLExpressionStatement.h" |
| #include "src/sksl/ir/SkSLExternalFunctionCall.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/SkSLIfStatement.h" |
| #include "src/sksl/ir/SkSLIndexExpression.h" |
| #include "src/sksl/ir/SkSLLiteral.h" |
| #include "src/sksl/ir/SkSLNop.h" |
| #include "src/sksl/ir/SkSLPostfixExpression.h" |
| #include "src/sksl/ir/SkSLPrefixExpression.h" |
| #include "src/sksl/ir/SkSLReturnStatement.h" |
| #include "src/sksl/ir/SkSLSetting.h" |
| #include "src/sksl/ir/SkSLSwitchCase.h" |
| #include "src/sksl/ir/SkSLSwitchStatement.h" |
| #include "src/sksl/ir/SkSLSwizzle.h" |
| #include "src/sksl/ir/SkSLSymbolTable.h" |
| #include "src/sksl/ir/SkSLTernaryExpression.h" |
| #include "src/sksl/ir/SkSLType.h" |
| #include "src/sksl/ir/SkSLVarDeclarations.h" |
| #include "src/sksl/ir/SkSLVariable.h" |
| #include "src/sksl/ir/SkSLVariableReference.h" |
| #include "src/sksl/transform/SkSLTransform.h" |
| |
| #include <algorithm> |
| #include <climits> |
| #include <cstddef> |
| #include <memory> |
| #include <string> |
| #include <string_view> |
| #include <utility> |
| |
| namespace SkSL { |
| namespace { |
| |
| static constexpr int kInlinedStatementLimit = 2500; |
| |
| static std::unique_ptr<Statement>* find_parent_statement( |
| const std::vector<std::unique_ptr<Statement>*>& stmtStack) { |
| SkASSERT(!stmtStack.empty()); |
| |
| // Walk the statement stack from back to front, ignoring the last element (which is the |
| // enclosing statement). |
| auto iter = stmtStack.rbegin(); |
| ++iter; |
| |
| // Anything counts as a parent statement other than a scopeless Block. |
| for (; iter != stmtStack.rend(); ++iter) { |
| std::unique_ptr<Statement>* stmt = *iter; |
| if (!(*stmt)->is<Block>() || (*stmt)->as<Block>().isScope()) { |
| return stmt; |
| } |
| } |
| |
| // There wasn't any parent statement to be found. |
| return nullptr; |
| } |
| |
| std::unique_ptr<Expression> clone_with_ref_kind(const Expression& expr, |
| VariableReference::RefKind refKind) { |
| std::unique_ptr<Expression> clone = expr.clone(); |
| Analysis::UpdateVariableRefKind(clone.get(), refKind); |
| return clone; |
| } |
| |
| } // namespace |
| |
| const Variable* Inliner::RemapVariable(const Variable* variable, |
| const VariableRewriteMap* varMap) { |
| std::unique_ptr<Expression>* remap = varMap->find(variable); |
| if (!remap) { |
| SkDEBUGFAILF("rewrite map does not contain variable '%.*s'", |
| (int)variable->name().size(), variable->name().data()); |
| return variable; |
| } |
| Expression* expr = remap->get(); |
| SkASSERT(expr); |
| if (!expr->is<VariableReference>()) { |
| SkDEBUGFAILF("rewrite map contains non-variable replacement for '%.*s'", |
| (int)variable->name().size(), variable->name().data()); |
| return variable; |
| } |
| return expr->as<VariableReference>().variable(); |
| } |
| |
| void Inliner::ensureScopedBlocks(Statement* inlinedBody, Statement* parentStmt) { |
| // No changes necessary if this statement isn't actually a block. |
| if (!inlinedBody || !inlinedBody->is<Block>()) { |
| return; |
| } |
| |
| // No changes necessary if the parent statement doesn't require a scope. |
| if (!parentStmt || !(parentStmt->is<IfStatement>() || parentStmt->is<ForStatement>() || |
| parentStmt->is<DoStatement>())) { |
| return; |
| } |
| |
| Block& block = inlinedBody->as<Block>(); |
| |
| // The inliner will create inlined function bodies as a Block containing multiple statements, |
| // but no scope. Normally, this is fine, but if this block is used as the statement for a |
| // do/for/if/while, the block needs to be scoped for the generated code to match the intent. |
| // In the case of Blocks nested inside other Blocks, we add the scope to the outermost block if |
| // needed. |
| for (Block* nestedBlock = █; ) { |
| if (nestedBlock->isScope()) { |
| // We found an explicit scope; all is well. |
| return; |
| } |
| if (nestedBlock->children().size() == 1 && nestedBlock->children()[0]->is<Block>()) { |
| // This block wraps another unscoped block; we need to go deeper. |
| nestedBlock = &nestedBlock->children()[0]->as<Block>(); |
| continue; |
| } |
| // We found a block containing real statements (not just more blocks), but no scope. |
| // Let's add a scope to the outermost block. |
| block.setBlockKind(Block::Kind::kBracedScope); |
| return; |
| } |
| } |
| |
| std::unique_ptr<Expression> Inliner::inlineExpression(Position pos, |
| VariableRewriteMap* varMap, |
| SymbolTable* symbolTableForExpression, |
| const Expression& expression) { |
| auto expr = [&](const std::unique_ptr<Expression>& e) -> std::unique_ptr<Expression> { |
| if (e) { |
| return this->inlineExpression(pos, varMap, symbolTableForExpression, *e); |
| } |
| return nullptr; |
| }; |
| auto argList = [&](const ExpressionArray& originalArgs) -> ExpressionArray { |
| ExpressionArray args; |
| args.reserve_back(originalArgs.size()); |
| for (const std::unique_ptr<Expression>& arg : originalArgs) { |
| args.push_back(expr(arg)); |
| } |
| return args; |
| }; |
| |
| switch (expression.kind()) { |
| case Expression::Kind::kBinary: { |
| const BinaryExpression& binaryExpr = expression.as<BinaryExpression>(); |
| return BinaryExpression::Make(*fContext, |
| pos, |
| expr(binaryExpr.left()), |
| binaryExpr.getOperator(), |
| expr(binaryExpr.right())); |
| } |
| case Expression::Kind::kLiteral: |
| return expression.clone(); |
| case Expression::Kind::kChildCall: { |
| const ChildCall& childCall = expression.as<ChildCall>(); |
| return ChildCall::Make(*fContext, |
| pos, |
| childCall.type().clone(symbolTableForExpression), |
| childCall.child(), |
| argList(childCall.arguments())); |
| } |
| case Expression::Kind::kConstructorArray: { |
| const ConstructorArray& ctor = expression.as<ConstructorArray>(); |
| return ConstructorArray::Make(*fContext, pos, |
| *ctor.type().clone(symbolTableForExpression), |
| argList(ctor.arguments())); |
| } |
| case Expression::Kind::kConstructorArrayCast: { |
| const ConstructorArrayCast& ctor = expression.as<ConstructorArrayCast>(); |
| return ConstructorArrayCast::Make(*fContext, pos, |
| *ctor.type().clone(symbolTableForExpression), |
| expr(ctor.argument())); |
| } |
| case Expression::Kind::kConstructorCompound: { |
| const ConstructorCompound& ctor = expression.as<ConstructorCompound>(); |
| return ConstructorCompound::Make(*fContext, pos, |
| *ctor.type().clone(symbolTableForExpression), |
| argList(ctor.arguments())); |
| } |
| case Expression::Kind::kConstructorCompoundCast: { |
| const ConstructorCompoundCast& ctor = expression.as<ConstructorCompoundCast>(); |
| return ConstructorCompoundCast::Make(*fContext, pos, |
| *ctor.type().clone(symbolTableForExpression), |
| expr(ctor.argument())); |
| } |
| case Expression::Kind::kConstructorDiagonalMatrix: { |
| const ConstructorDiagonalMatrix& ctor = expression.as<ConstructorDiagonalMatrix>(); |
| return ConstructorDiagonalMatrix::Make(*fContext, pos, |
| *ctor.type().clone(symbolTableForExpression), |
| expr(ctor.argument())); |
| } |
| case Expression::Kind::kConstructorMatrixResize: { |
| const ConstructorMatrixResize& ctor = expression.as<ConstructorMatrixResize>(); |
| return ConstructorMatrixResize::Make(*fContext, pos, |
| *ctor.type().clone(symbolTableForExpression), |
| expr(ctor.argument())); |
| } |
| case Expression::Kind::kConstructorScalarCast: { |
| const ConstructorScalarCast& ctor = expression.as<ConstructorScalarCast>(); |
| return ConstructorScalarCast::Make(*fContext, pos, |
| *ctor.type().clone(symbolTableForExpression), |
| expr(ctor.argument())); |
| } |
| case Expression::Kind::kConstructorSplat: { |
| const ConstructorSplat& ctor = expression.as<ConstructorSplat>(); |
| return ConstructorSplat::Make(*fContext, pos, |
| *ctor.type().clone(symbolTableForExpression), |
| expr(ctor.argument())); |
| } |
| case Expression::Kind::kConstructorStruct: { |
| const ConstructorStruct& ctor = expression.as<ConstructorStruct>(); |
| return ConstructorStruct::Make(*fContext, pos, |
| *ctor.type().clone(symbolTableForExpression), |
| argList(ctor.arguments())); |
| } |
| case Expression::Kind::kExternalFunctionCall: { |
| const ExternalFunctionCall& externalCall = expression.as<ExternalFunctionCall>(); |
| return std::make_unique<ExternalFunctionCall>(pos, &externalCall.function(), |
| argList(externalCall.arguments())); |
| } |
| case Expression::Kind::kExternalFunctionReference: |
| return expression.clone(); |
| case Expression::Kind::kFieldAccess: { |
| const FieldAccess& f = expression.as<FieldAccess>(); |
| return FieldAccess::Make(*fContext, pos, expr(f.base()), f.fieldIndex(), f.ownerKind()); |
| } |
| case Expression::Kind::kFunctionCall: { |
| const FunctionCall& funcCall = expression.as<FunctionCall>(); |
| return FunctionCall::Make(*fContext, |
| pos, |
| funcCall.type().clone(symbolTableForExpression), |
| funcCall.function(), |
| argList(funcCall.arguments())); |
| } |
| case Expression::Kind::kFunctionReference: |
| return expression.clone(); |
| case Expression::Kind::kIndex: { |
| const IndexExpression& idx = expression.as<IndexExpression>(); |
| return IndexExpression::Make(*fContext, pos, expr(idx.base()), expr(idx.index())); |
| } |
| case Expression::Kind::kMethodReference: |
| return expression.clone(); |
| case Expression::Kind::kPrefix: { |
| const PrefixExpression& p = expression.as<PrefixExpression>(); |
| return PrefixExpression::Make(*fContext, pos, p.getOperator(), expr(p.operand())); |
| } |
| case Expression::Kind::kPostfix: { |
| const PostfixExpression& p = expression.as<PostfixExpression>(); |
| return PostfixExpression::Make(*fContext, pos, expr(p.operand()), p.getOperator()); |
| } |
| case Expression::Kind::kSetting: { |
| const Setting& s = expression.as<Setting>(); |
| return Setting::Convert(*fContext, pos, s.name()); |
| } |
| case Expression::Kind::kSwizzle: { |
| const Swizzle& s = expression.as<Swizzle>(); |
| return Swizzle::Make(*fContext, pos, expr(s.base()), s.components()); |
| } |
| case Expression::Kind::kTernary: { |
| const TernaryExpression& t = expression.as<TernaryExpression>(); |
| return TernaryExpression::Make(*fContext, pos, expr(t.test()), |
| expr(t.ifTrue()), expr(t.ifFalse())); |
| } |
| case Expression::Kind::kTypeReference: |
| return expression.clone(); |
| case Expression::Kind::kVariableReference: { |
| const VariableReference& v = expression.as<VariableReference>(); |
| std::unique_ptr<Expression>* remap = varMap->find(v.variable()); |
| if (remap) { |
| return clone_with_ref_kind(**remap, v.refKind()); |
| } |
| return expression.clone(); |
| } |
| default: |
| SkASSERT(false); |
| return nullptr; |
| } |
| } |
| |
| std::unique_ptr<Statement> Inliner::inlineStatement(Position pos, |
| VariableRewriteMap* varMap, |
| SymbolTable* symbolTableForStatement, |
| std::unique_ptr<Expression>* resultExpr, |
| Analysis::ReturnComplexity returnComplexity, |
| const Statement& statement, |
| const ProgramUsage& usage, |
| bool isBuiltinCode) { |
| auto stmt = [&](const std::unique_ptr<Statement>& s) -> std::unique_ptr<Statement> { |
| if (s) { |
| return this->inlineStatement(pos, varMap, symbolTableForStatement, resultExpr, |
| returnComplexity, *s, usage, isBuiltinCode); |
| } |
| return nullptr; |
| }; |
| auto blockStmts = [&](const Block& block) { |
| StatementArray result; |
| result.reserve_back(block.children().size()); |
| for (const std::unique_ptr<Statement>& child : block.children()) { |
| result.push_back(stmt(child)); |
| } |
| return result; |
| }; |
| auto expr = [&](const std::unique_ptr<Expression>& e) -> std::unique_ptr<Expression> { |
| if (e) { |
| return this->inlineExpression(pos, varMap, symbolTableForStatement, *e); |
| } |
| return nullptr; |
| }; |
| auto variableModifiers = [&](const Variable& variable, |
| const Expression* initialValue) -> const Modifiers* { |
| return Transform::AddConstToVarModifiers(*fContext, variable, initialValue, &usage); |
| }; |
| |
| ++fInlinedStatementCounter; |
| |
| switch (statement.kind()) { |
| case Statement::Kind::kBlock: { |
| const Block& b = statement.as<Block>(); |
| return Block::Make(pos, blockStmts(b), b.blockKind(), |
| SymbolTable::WrapIfBuiltin(b.symbolTable())); |
| } |
| |
| case Statement::Kind::kBreak: |
| case Statement::Kind::kContinue: |
| case Statement::Kind::kDiscard: |
| return statement.clone(); |
| |
| case Statement::Kind::kDo: { |
| const DoStatement& d = statement.as<DoStatement>(); |
| return DoStatement::Make(*fContext, pos, stmt(d.statement()), expr(d.test())); |
| } |
| case Statement::Kind::kExpression: { |
| const ExpressionStatement& e = statement.as<ExpressionStatement>(); |
| return ExpressionStatement::Make(*fContext, expr(e.expression())); |
| } |
| case Statement::Kind::kFor: { |
| const ForStatement& f = statement.as<ForStatement>(); |
| // need to ensure initializer is evaluated first so that we've already remapped its |
| // declarations by the time we evaluate test & next |
| std::unique_ptr<Statement> initializer = stmt(f.initializer()); |
| |
| std::unique_ptr<LoopUnrollInfo> unrollInfo; |
| if (f.unrollInfo()) { |
| // The for loop's unroll-info points to the Variable in the initializer as the |
| // index. This variable has been rewritten into a clone by the inliner, so we need |
| // to update the loop-unroll info to point to the clone. |
| unrollInfo = std::make_unique<LoopUnrollInfo>(*f.unrollInfo()); |
| unrollInfo->fIndex = RemapVariable(unrollInfo->fIndex, varMap); |
| } |
| return ForStatement::Make(*fContext, pos, ForLoopPositions{}, std::move(initializer), |
| expr(f.test()), expr(f.next()), stmt(f.statement()), |
| std::move(unrollInfo), |
| SymbolTable::WrapIfBuiltin(f.symbols())); |
| } |
| case Statement::Kind::kIf: { |
| const IfStatement& i = statement.as<IfStatement>(); |
| return IfStatement::Make(*fContext, pos, expr(i.test()), |
| stmt(i.ifTrue()), stmt(i.ifFalse())); |
| } |
| case Statement::Kind::kNop: |
| return statement.clone(); |
| |
| case Statement::Kind::kReturn: { |
| const ReturnStatement& r = statement.as<ReturnStatement>(); |
| if (!r.expression()) { |
| // This function doesn't return a value. We won't inline functions with early |
| // returns, so a return statement is a no-op and can be treated as such. |
| return Nop::Make(); |
| } |
| |
| // If a function only contains a single return, and it doesn't reference variables from |
| // inside an Block's scope, we don't need to store the result in a variable at all. Just |
| // replace the function-call expression with the function's return expression. |
| SkASSERT(resultExpr); |
| if (returnComplexity <= Analysis::ReturnComplexity::kSingleSafeReturn) { |
| *resultExpr = expr(r.expression()); |
| return Nop::Make(); |
| } |
| |
| // For more complex functions, we assign their result into a variable. We refuse to |
| // inline anything with early returns, so this should be safe to do; that is, on this |
| // control path, this is the last statement that will occur. |
| SkASSERT(*resultExpr); |
| return ExpressionStatement::Make( |
| *fContext, |
| BinaryExpression::Make( |
| *fContext, |
| pos, |
| clone_with_ref_kind(**resultExpr, VariableRefKind::kWrite), |
| Operator::Kind::EQ, |
| expr(r.expression()))); |
| } |
| case Statement::Kind::kSwitch: { |
| const SwitchStatement& ss = statement.as<SwitchStatement>(); |
| StatementArray cases; |
| cases.reserve_back(ss.cases().size()); |
| for (const std::unique_ptr<Statement>& switchCaseStmt : ss.cases()) { |
| const SwitchCase& sc = switchCaseStmt->as<SwitchCase>(); |
| if (sc.isDefault()) { |
| cases.push_back(SwitchCase::MakeDefault(pos, stmt(sc.statement()))); |
| } else { |
| cases.push_back(SwitchCase::Make(pos, sc.value(), stmt(sc.statement()))); |
| } |
| } |
| return SwitchStatement::Make(*fContext, pos, expr(ss.value()), |
| std::move(cases), SymbolTable::WrapIfBuiltin(ss.symbols())); |
| } |
| case Statement::Kind::kVarDeclaration: { |
| const VarDeclaration& decl = statement.as<VarDeclaration>(); |
| std::unique_ptr<Expression> initialValue = expr(decl.value()); |
| const Variable* variable = decl.var(); |
| |
| // We assign unique names to inlined variables--scopes hide most of the problems in this |
| // regard, but see `InlinerAvoidsVariableNameOverlap` for a counterexample where unique |
| // names are important. |
| const std::string* name = symbolTableForStatement->takeOwnershipOfString( |
| fMangler.uniqueName(variable->name(), symbolTableForStatement)); |
| auto clonedVar = std::make_unique<Variable>( |
| pos, |
| variable->modifiersPosition(), |
| variableModifiers(*variable, initialValue.get()), |
| name->c_str(), |
| variable->type().clone(symbolTableForStatement), |
| isBuiltinCode, |
| variable->storage()); |
| varMap->set(variable, VariableReference::Make(pos, clonedVar.get())); |
| auto result = VarDeclaration::Make(*fContext, |
| clonedVar.get(), |
| decl.baseType().clone(symbolTableForStatement), |
| decl.arraySize(), |
| std::move(initialValue)); |
| symbolTableForStatement->takeOwnershipOfSymbol(std::move(clonedVar)); |
| return result; |
| } |
| default: |
| SkASSERT(false); |
| return nullptr; |
| } |
| } |
| |
| Inliner::InlinedCall Inliner::inlineCall(const FunctionCall& call, |
| std::shared_ptr<SymbolTable> symbolTable, |
| const ProgramUsage& usage, |
| const FunctionDeclaration* caller) { |
| using ScratchVariable = Variable::ScratchVariable; |
| |
| // Inlining is more complicated here than in a typical compiler, because we have to have a |
| // high-level IR and can't just drop statements into the middle of an expression or even use |
| // gotos. |
| // |
| // Since we can't insert statements into an expression, we run the inline function as extra |
| // statements before the statement we're currently processing, relying on a lack of execution |
| // order guarantees. Since we can't use gotos (which are normally used to replace return |
| // statements), we wrap the whole function in a loop and use break statements to jump to the |
| // end. |
| SkASSERT(fContext); |
| SkASSERT(this->isSafeToInline(call.function().definition(), usage)); |
| |
| const ExpressionArray& arguments = call.arguments(); |
| const Position pos = call.fPosition; |
| const FunctionDefinition& function = *call.function().definition(); |
| const Block& body = function.body()->as<Block>(); |
| const Analysis::ReturnComplexity returnComplexity = Analysis::GetReturnComplexity(function); |
| |
| StatementArray inlineStatements; |
| int expectedStmtCount = 1 + // Result variable |
| arguments.size() + // Function argument temp-vars |
| body.children().size(); // Inlined code |
| |
| inlineStatements.reserve_back(expectedStmtCount); |
| |
| std::unique_ptr<Expression> resultExpr; |
| if (returnComplexity > Analysis::ReturnComplexity::kSingleSafeReturn && |
| !function.declaration().returnType().isVoid()) { |
| // Create a variable to hold the result in the extra statements. We don't need to do this |
| // for void-return functions, or in cases that are simple enough that we can just replace |
| // the function-call node with the result expression. |
| ScratchVariable var = Variable::MakeScratchVariable(*fContext, |
| fMangler, |
| function.declaration().name(), |
| &function.declaration().returnType(), |
| Modifiers{}, |
| symbolTable.get(), |
| /*initialValue=*/nullptr); |
| inlineStatements.push_back(std::move(var.fVarDecl)); |
| resultExpr = VariableReference::Make(Position(), var.fVarSymbol); |
| } |
| |
| // Create variables in the extra statements to hold the arguments, and assign the arguments to |
| // them. |
| VariableRewriteMap varMap; |
| for (int i = 0; i < arguments.size(); ++i) { |
| // If the parameter isn't written to within the inline function ... |
| const Expression* arg = arguments[i].get(); |
| const Variable* param = function.declaration().parameters()[i]; |
| const ProgramUsage::VariableCounts& paramUsage = usage.get(*param); |
| if (!paramUsage.fWrite) { |
| // ... and can be inlined trivially (e.g. a swizzle, or a constant array index), |
| // or any expression without side effects that is only accessed at most once... |
| if ((paramUsage.fRead > 1) ? Analysis::IsTrivialExpression(*arg) |
| : !Analysis::HasSideEffects(*arg)) { |
| // ... we don't need to copy it at all! We can just use the existing expression. |
| varMap.set(param, arg->clone()); |
| continue; |
| } |
| } |
| ScratchVariable var = Variable::MakeScratchVariable(*fContext, |
| fMangler, |
| param->name(), |
| &arg->type(), |
| param->modifiers(), |
| symbolTable.get(), |
| arg->clone()); |
| inlineStatements.push_back(std::move(var.fVarDecl)); |
| varMap.set(param, VariableReference::Make(Position(), var.fVarSymbol)); |
| } |
| |
| for (const std::unique_ptr<Statement>& stmt : body.children()) { |
| inlineStatements.push_back(this->inlineStatement(pos, &varMap, symbolTable.get(), |
| &resultExpr, returnComplexity, *stmt, |
| usage, caller->isBuiltin())); |
| } |
| |
| SkASSERT(inlineStatements.size() <= expectedStmtCount); |
| |
| // Wrap all of the generated statements in a block. We need a real Block here, because we need |
| // to add another child statement to the Block later. |
| InlinedCall inlinedCall; |
| inlinedCall.fInlinedBody = Block::MakeBlock(pos, std::move(inlineStatements), |
| Block::Kind::kUnbracedBlock); |
| if (resultExpr) { |
| // Return our result expression as-is. |
| inlinedCall.fReplacementExpr = std::move(resultExpr); |
| } else if (function.declaration().returnType().isVoid()) { |
| // It's a void function, so it doesn't actually result in anything, but we have to return |
| // something non-null as a standin. |
| inlinedCall.fReplacementExpr = Literal::MakeBool(*fContext, pos, /*value=*/false); |
| } else { |
| // It's a non-void function, but it never created a result expression--that is, it never |
| // returned anything on any path! This should have been detected in the function finalizer. |
| // Still, discard our output and generate an error. |
| SkDEBUGFAIL("inliner found non-void function that fails to return a value on any path"); |
| fContext->fErrors->error(function.fPosition, "inliner found non-void function '" + |
| std::string(function.declaration().name()) + |
| "' that fails to return a value on any path"); |
| inlinedCall = {}; |
| } |
| |
| return inlinedCall; |
| } |
| |
| bool Inliner::isSafeToInline(const FunctionDefinition* functionDef, const ProgramUsage& usage) { |
| // A threshold of zero indicates that the inliner is completely disabled, so we can just return. |
| if (this->settings().fInlineThreshold <= 0) { |
| return false; |
| } |
| |
| // Enforce a limit on inlining to avoid pathological cases. (inliner/ExponentialGrowth.sksl) |
| if (fInlinedStatementCounter >= kInlinedStatementLimit) { |
| return false; |
| } |
| |
| if (functionDef == nullptr) { |
| // Can't inline something if we don't actually have its definition. |
| return false; |
| } |
| |
| if (functionDef->declaration().modifiers().fFlags & Modifiers::kNoInline_Flag) { |
| // Refuse to inline functions decorated with `noinline`. |
| return false; |
| } |
| |
| // We don't allow inlining a function with out parameters that are written to. |
| // (See skia:11326 for rationale.) |
| for (const Variable* param : functionDef->declaration().parameters()) { |
| if (param->modifiers().fFlags & Modifiers::Flag::kOut_Flag) { |
| ProgramUsage::VariableCounts counts = usage.get(*param); |
| if (counts.fWrite > 0) { |
| return false; |
| } |
| } |
| } |
| |
| // We don't have a mechanism to simulate early returns, so we can't inline if there is one. |
| return Analysis::GetReturnComplexity(*functionDef) < Analysis::ReturnComplexity::kEarlyReturns; |
| } |
| |
| // A candidate function for inlining, containing everything that `inlineCall` needs. |
| struct InlineCandidate { |
| std::shared_ptr<SymbolTable> fSymbols; // the SymbolTable of the candidate |
| std::unique_ptr<Statement>* fParentStmt; // the parent Statement of the enclosing stmt |
| std::unique_ptr<Statement>* fEnclosingStmt; // the Statement containing the candidate |
| std::unique_ptr<Expression>* fCandidateExpr; // the candidate FunctionCall to be inlined |
| FunctionDefinition* fEnclosingFunction; // the Function containing the candidate |
| }; |
| |
| struct InlineCandidateList { |
| std::vector<InlineCandidate> fCandidates; |
| }; |
| |
| class InlineCandidateAnalyzer { |
| public: |
| // A list of all the inlining candidates we found during analysis. |
| InlineCandidateList* fCandidateList; |
| |
| // A stack of the symbol tables; since most nodes don't have one, expected to be shallower than |
| // the enclosing-statement stack. |
| std::vector<std::shared_ptr<SymbolTable>> fSymbolTableStack; |
| // A stack of "enclosing" statements--these would be suitable for the inliner to use for adding |
| // new instructions. Not all statements are suitable (e.g. a for-loop's initializer). The |
| // inliner might replace a statement with a block containing the statement. |
| std::vector<std::unique_ptr<Statement>*> fEnclosingStmtStack; |
| // The function that we're currently processing (i.e. inlining into). |
| FunctionDefinition* fEnclosingFunction = nullptr; |
| |
| void visit(const std::vector<std::unique_ptr<ProgramElement>>& elements, |
| std::shared_ptr<SymbolTable> symbols, |
| InlineCandidateList* candidateList) { |
| fCandidateList = candidateList; |
| fSymbolTableStack.push_back(symbols); |
| |
| for (const std::unique_ptr<ProgramElement>& pe : elements) { |
| this->visitProgramElement(pe.get()); |
| } |
| |
| fSymbolTableStack.pop_back(); |
| fCandidateList = nullptr; |
| } |
| |
| void visitProgramElement(ProgramElement* pe) { |
| switch (pe->kind()) { |
| case ProgramElement::Kind::kFunction: { |
| FunctionDefinition& funcDef = pe->as<FunctionDefinition>(); |
| fEnclosingFunction = &funcDef; |
| this->visitStatement(&funcDef.body()); |
| break; |
| } |
| default: |
| // The inliner can't operate outside of a function's scope. |
| break; |
| } |
| } |
| |
| void visitStatement(std::unique_ptr<Statement>* stmt, |
| bool isViableAsEnclosingStatement = true) { |
| if (!*stmt) { |
| return; |
| } |
| |
| Analysis::SymbolTableStackBuilder scopedStackBuilder(stmt->get(), &fSymbolTableStack); |
| size_t oldEnclosingStmtStackSize = fEnclosingStmtStack.size(); |
| |
| if (isViableAsEnclosingStatement) { |
| fEnclosingStmtStack.push_back(stmt); |
| } |
| |
| switch ((*stmt)->kind()) { |
| case Statement::Kind::kBreak: |
| case Statement::Kind::kContinue: |
| case Statement::Kind::kDiscard: |
| case Statement::Kind::kNop: |
| break; |
| |
| case Statement::Kind::kBlock: { |
| Block& block = (*stmt)->as<Block>(); |
| for (std::unique_ptr<Statement>& blockStmt : block.children()) { |
| this->visitStatement(&blockStmt); |
| } |
| break; |
| } |
| case Statement::Kind::kDo: { |
| DoStatement& doStmt = (*stmt)->as<DoStatement>(); |
| // The loop body is a candidate for inlining. |
| this->visitStatement(&doStmt.statement()); |
| // The inliner isn't smart enough to inline the test-expression for a do-while |
| // loop at this time. There are two limitations: |
| // - We would need to insert the inlined-body block at the very end of the do- |
| // statement's inner fStatement. We don't support that today, but it's doable. |
| // - We cannot inline the test expression if the loop uses `continue` anywhere; that |
| // would skip over the inlined block that evaluates the test expression. There |
| // isn't a good fix for this--any workaround would be more complex than the cost |
| // of a function call. However, loops that don't use `continue` would still be |
| // viable candidates for inlining. |
| break; |
| } |
| case Statement::Kind::kExpression: { |
| ExpressionStatement& expr = (*stmt)->as<ExpressionStatement>(); |
| this->visitExpression(&expr.expression()); |
| break; |
| } |
| case Statement::Kind::kFor: { |
| ForStatement& forStmt = (*stmt)->as<ForStatement>(); |
| // The initializer and loop body are candidates for inlining. |
| this->visitStatement(&forStmt.initializer(), |
| /*isViableAsEnclosingStatement=*/false); |
| this->visitStatement(&forStmt.statement()); |
| |
| // The inliner isn't smart enough to inline the test- or increment-expressions |
| // of a for loop loop at this time. There are a handful of limitations: |
| // - We would need to insert the test-expression block at the very beginning of the |
| // for-loop's inner fStatement, and the increment-expression block at the very |
| // end. We don't support that today, but it's doable. |
| // - The for-loop's built-in test-expression would need to be dropped entirely, |
| // and the loop would be halted via a break statement at the end of the inlined |
| // test-expression. This is again something we don't support today, but it could |
| // be implemented. |
| // - We cannot inline the increment-expression if the loop uses `continue` anywhere; |
| // that would skip over the inlined block that evaluates the increment expression. |
| // There isn't a good fix for this--any workaround would be more complex than the |
| // cost of a function call. However, loops that don't use `continue` would still |
| // be viable candidates for increment-expression inlining. |
| break; |
| } |
| case Statement::Kind::kIf: { |
| IfStatement& ifStmt = (*stmt)->as<IfStatement>(); |
| this->visitExpression(&ifStmt.test()); |
| this->visitStatement(&ifStmt.ifTrue()); |
| this->visitStatement(&ifStmt.ifFalse()); |
| break; |
| } |
| case Statement::Kind::kReturn: { |
| ReturnStatement& returnStmt = (*stmt)->as<ReturnStatement>(); |
| this->visitExpression(&returnStmt.expression()); |
| break; |
| } |
| case Statement::Kind::kSwitch: { |
| SwitchStatement& switchStmt = (*stmt)->as<SwitchStatement>(); |
| this->visitExpression(&switchStmt.value()); |
| for (const std::unique_ptr<Statement>& switchCase : switchStmt.cases()) { |
| // The switch-case's fValue cannot be a FunctionCall; skip it. |
| this->visitStatement(&switchCase->as<SwitchCase>().statement()); |
| } |
| break; |
| } |
| case Statement::Kind::kVarDeclaration: { |
| VarDeclaration& varDeclStmt = (*stmt)->as<VarDeclaration>(); |
| // Don't need to scan the declaration's sizes; those are always IntLiterals. |
| this->visitExpression(&varDeclStmt.value()); |
| break; |
| } |
| default: |
| SkUNREACHABLE; |
| } |
| |
| // Pop our symbol and enclosing-statement stacks. |
| fEnclosingStmtStack.resize(oldEnclosingStmtStackSize); |
| } |
| |
| void visitExpression(std::unique_ptr<Expression>* expr) { |
| if (!*expr) { |
| return; |
| } |
| |
| switch ((*expr)->kind()) { |
| case Expression::Kind::kExternalFunctionReference: |
| case Expression::Kind::kFieldAccess: |
| case Expression::Kind::kFunctionReference: |
| case Expression::Kind::kLiteral: |
| case Expression::Kind::kMethodReference: |
| case Expression::Kind::kSetting: |
| case Expression::Kind::kTypeReference: |
| case Expression::Kind::kVariableReference: |
| // Nothing to scan here. |
| break; |
| |
| case Expression::Kind::kBinary: { |
| BinaryExpression& binaryExpr = (*expr)->as<BinaryExpression>(); |
| this->visitExpression(&binaryExpr.left()); |
| |
| // Logical-and and logical-or binary expressions do not inline the right side, |
| // because that would invalidate short-circuiting. That is, when evaluating |
| // expressions like these: |
| // (false && x()) // always false |
| // (true || y()) // always true |
| // It is illegal for side-effects from x() or y() to occur. The simplest way to |
| // enforce that rule is to avoid inlining the right side entirely. However, it is |
| // safe for other types of binary expression to inline both sides. |
| Operator op = binaryExpr.getOperator(); |
| bool shortCircuitable = (op.kind() == Operator::Kind::LOGICALAND || |
| op.kind() == Operator::Kind::LOGICALOR); |
| if (!shortCircuitable) { |
| this->visitExpression(&binaryExpr.right()); |
| } |
| break; |
| } |
| case Expression::Kind::kChildCall: { |
| ChildCall& childCallExpr = (*expr)->as<ChildCall>(); |
| for (std::unique_ptr<Expression>& arg : childCallExpr.arguments()) { |
| this->visitExpression(&arg); |
| } |
| break; |
| } |
| case Expression::Kind::kConstructorArray: |
| case Expression::Kind::kConstructorArrayCast: |
| case Expression::Kind::kConstructorCompound: |
| case Expression::Kind::kConstructorCompoundCast: |
| case Expression::Kind::kConstructorDiagonalMatrix: |
| case Expression::Kind::kConstructorMatrixResize: |
| case Expression::Kind::kConstructorScalarCast: |
| case Expression::Kind::kConstructorSplat: |
| case Expression::Kind::kConstructorStruct: { |
| AnyConstructor& constructorExpr = (*expr)->asAnyConstructor(); |
| for (std::unique_ptr<Expression>& arg : constructorExpr.argumentSpan()) { |
| this->visitExpression(&arg); |
| } |
| break; |
| } |
| case Expression::Kind::kExternalFunctionCall: { |
| ExternalFunctionCall& funcCallExpr = (*expr)->as<ExternalFunctionCall>(); |
| for (std::unique_ptr<Expression>& arg : funcCallExpr.arguments()) { |
| this->visitExpression(&arg); |
| } |
| break; |
| } |
| case Expression::Kind::kFunctionCall: { |
| FunctionCall& funcCallExpr = (*expr)->as<FunctionCall>(); |
| for (std::unique_ptr<Expression>& arg : funcCallExpr.arguments()) { |
| this->visitExpression(&arg); |
| } |
| this->addInlineCandidate(expr); |
| break; |
| } |
| case Expression::Kind::kIndex: { |
| IndexExpression& indexExpr = (*expr)->as<IndexExpression>(); |
| this->visitExpression(&indexExpr.base()); |
| this->visitExpression(&indexExpr.index()); |
| break; |
| } |
| case Expression::Kind::kPostfix: { |
| PostfixExpression& postfixExpr = (*expr)->as<PostfixExpression>(); |
| this->visitExpression(&postfixExpr.operand()); |
| break; |
| } |
| case Expression::Kind::kPrefix: { |
| PrefixExpression& prefixExpr = (*expr)->as<PrefixExpression>(); |
| this->visitExpression(&prefixExpr.operand()); |
| break; |
| } |
| case Expression::Kind::kSwizzle: { |
| Swizzle& swizzleExpr = (*expr)->as<Swizzle>(); |
| this->visitExpression(&swizzleExpr.base()); |
| break; |
| } |
| case Expression::Kind::kTernary: { |
| TernaryExpression& ternaryExpr = (*expr)->as<TernaryExpression>(); |
| // The test expression is a candidate for inlining. |
| this->visitExpression(&ternaryExpr.test()); |
| // The true- and false-expressions cannot be inlined, because we are only allowed to |
| // evaluate one side. |
| break; |
| } |
| default: |
| SkUNREACHABLE; |
| } |
| } |
| |
| void addInlineCandidate(std::unique_ptr<Expression>* candidate) { |
| fCandidateList->fCandidates.push_back( |
| InlineCandidate{fSymbolTableStack.back(), |
| find_parent_statement(fEnclosingStmtStack), |
| fEnclosingStmtStack.back(), |
| candidate, |
| fEnclosingFunction}); |
| } |
| }; |
| |
| static const FunctionDeclaration& candidate_func(const InlineCandidate& candidate) { |
| return (*candidate.fCandidateExpr)->as<FunctionCall>().function(); |
| } |
| |
| bool Inliner::candidateCanBeInlined(const InlineCandidate& candidate, |
| const ProgramUsage& usage, |
| InlinabilityCache* cache) { |
| const FunctionDeclaration& funcDecl = candidate_func(candidate); |
| if (const bool* cachedInlinability = cache->find(&funcDecl)) { |
| return *cachedInlinability; |
| } |
| bool inlinability = this->isSafeToInline(funcDecl.definition(), usage); |
| cache->set(&funcDecl, inlinability); |
| return inlinability; |
| } |
| |
| int Inliner::getFunctionSize(const FunctionDeclaration& funcDecl, FunctionSizeCache* cache) { |
| if (const int* cachedSize = cache->find(&funcDecl)) { |
| return *cachedSize; |
| } |
| int size = Analysis::NodeCountUpToLimit(*funcDecl.definition(), |
| this->settings().fInlineThreshold); |
| cache->set(&funcDecl, size); |
| return size; |
| } |
| |
| void Inliner::buildCandidateList(const std::vector<std::unique_ptr<ProgramElement>>& elements, |
| std::shared_ptr<SymbolTable> symbols, ProgramUsage* usage, |
| InlineCandidateList* candidateList) { |
| // This is structured much like a ProgramVisitor, but does not actually use ProgramVisitor. |
| // The analyzer needs to keep track of the `unique_ptr<T>*` of statements and expressions so |
| // that they can later be replaced, and ProgramVisitor does not provide this; it only provides a |
| // `const T&`. |
| InlineCandidateAnalyzer analyzer; |
| analyzer.visit(elements, symbols, candidateList); |
| |
| // Early out if there are no inlining candidates. |
| std::vector<InlineCandidate>& candidates = candidateList->fCandidates; |
| if (candidates.empty()) { |
| return; |
| } |
| |
| // Remove candidates that are not safe to inline. |
| InlinabilityCache cache; |
| candidates.erase(std::remove_if(candidates.begin(), |
| candidates.end(), |
| [&](const InlineCandidate& candidate) { |
| return !this->candidateCanBeInlined( |
| candidate, *usage, &cache); |
| }), |
| candidates.end()); |
| |
| // If the inline threshold is unlimited, or if we have no candidates left, our candidate list is |
| // complete. |
| if (this->settings().fInlineThreshold == INT_MAX || candidates.empty()) { |
| return; |
| } |
| |
| // Remove candidates on a per-function basis if the effect of inlining would be to make more |
| // than `inlineThreshold` nodes. (i.e. if Func() would be inlined six times and its size is |
| // 10 nodes, it should be inlined if the inlineThreshold is 60 or higher.) |
| FunctionSizeCache functionSizeCache; |
| FunctionSizeCache candidateTotalCost; |
| for (InlineCandidate& candidate : candidates) { |
| const FunctionDeclaration& fnDecl = candidate_func(candidate); |
| candidateTotalCost[&fnDecl] += this->getFunctionSize(fnDecl, &functionSizeCache); |
| } |
| |
| candidates.erase(std::remove_if(candidates.begin(), candidates.end(), |
| [&](const InlineCandidate& candidate) { |
| const FunctionDeclaration& fnDecl = candidate_func(candidate); |
| if (fnDecl.modifiers().fFlags & Modifiers::kInline_Flag) { |
| // Functions marked `inline` ignore size limitations. |
| return false; |
| } |
| if (usage->get(fnDecl) == 1) { |
| // If a function is only used once, it's cost-free to inline. |
| return false; |
| } |
| if (candidateTotalCost[&fnDecl] <= this->settings().fInlineThreshold) { |
| // We won't exceed the inline threshold by inlining this. |
| return false; |
| } |
| // Inlining this function will add too many IRNodes. |
| return true; |
| }), |
| candidates.end()); |
| } |
| |
| bool Inliner::analyze(const std::vector<std::unique_ptr<ProgramElement>>& elements, |
| std::shared_ptr<SymbolTable> symbols, |
| ProgramUsage* usage) { |
| // A threshold of zero indicates that the inliner is completely disabled, so we can just return. |
| if (this->settings().fInlineThreshold <= 0) { |
| return false; |
| } |
| |
| // Enforce a limit on inlining to avoid pathological cases. (inliner/ExponentialGrowth.sksl) |
| if (fInlinedStatementCounter >= kInlinedStatementLimit) { |
| return false; |
| } |
| |
| InlineCandidateList candidateList; |
| this->buildCandidateList(elements, symbols, usage, &candidateList); |
| |
| // Inline the candidates where we've determined that it's safe to do so. |
| using StatementRemappingTable = SkTHashMap<std::unique_ptr<Statement>*, |
| std::unique_ptr<Statement>*>; |
| StatementRemappingTable statementRemappingTable; |
| |
| bool madeChanges = false; |
| for (const InlineCandidate& candidate : candidateList.fCandidates) { |
| const FunctionCall& funcCall = (*candidate.fCandidateExpr)->as<FunctionCall>(); |
| |
| // Convert the function call to its inlined equivalent. |
| InlinedCall inlinedCall = this->inlineCall(funcCall, candidate.fSymbols, *usage, |
| &candidate.fEnclosingFunction->declaration()); |
| |
| // Stop if an error was detected during the inlining process. |
| if (!inlinedCall.fInlinedBody && !inlinedCall.fReplacementExpr) { |
| break; |
| } |
| |
| // Ensure that the inlined body has a scope if it needs one. |
| this->ensureScopedBlocks(inlinedCall.fInlinedBody.get(), candidate.fParentStmt->get()); |
| |
| // Add references within the inlined body |
| usage->add(inlinedCall.fInlinedBody.get()); |
| |
| // Look up the enclosing statement; remap it if necessary. |
| std::unique_ptr<Statement>* enclosingStmt = candidate.fEnclosingStmt; |
| for (;;) { |
| std::unique_ptr<Statement>** remappedStmt = statementRemappingTable.find(enclosingStmt); |
| if (!remappedStmt) { |
| break; |
| } |
| enclosingStmt = *remappedStmt; |
| } |
| |
| // Move the enclosing statement to the end of the unscoped Block containing the inlined |
| // function, then replace the enclosing statement with that Block. |
| // Before: |
| // fInlinedBody = Block{ stmt1, stmt2, stmt3 } |
| // fEnclosingStmt = stmt4 |
| // After: |
| // fInlinedBody = null |
| // fEnclosingStmt = Block{ stmt1, stmt2, stmt3, stmt4 } |
| inlinedCall.fInlinedBody->children().push_back(std::move(*enclosingStmt)); |
| *enclosingStmt = std::move(inlinedCall.fInlinedBody); |
| |
| // Replace the candidate function call with our replacement expression. |
| usage->remove(candidate.fCandidateExpr->get()); |
| usage->add(inlinedCall.fReplacementExpr.get()); |
| *candidate.fCandidateExpr = std::move(inlinedCall.fReplacementExpr); |
| madeChanges = true; |
| |
| // If anything else pointed at our enclosing statement, it's now pointing at a Block |
| // containing many other statements as well. Maintain a fix-up table to account for this. |
| statementRemappingTable.set(enclosingStmt,&(*enclosingStmt)->as<Block>().children().back()); |
| |
| // Stop inlining if we've reached our hard cap on new statements. |
| if (fInlinedStatementCounter >= kInlinedStatementLimit) { |
| break; |
| } |
| |
| // Note that nothing was destroyed except for the FunctionCall. All other nodes should |
| // remain valid. |
| } |
| |
| return madeChanges; |
| } |
| |
| } // namespace SkSL |
| |
| #endif // SK_ENABLE_OPTIMIZE_SIZE |
