blob: eaba2d6eff129cfb31a46efb8ffa98c0e12a8316 [file] [log] [blame]
/*
* Copyright 2021 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/SkSLMangler.h"
#include "include/core/SkString.h"
#include "include/core/SkTypes.h"
#include "include/private/SkStringView.h"
#include "src/sksl/ir/SkSLSymbolTable.h"
#include <algorithm>
#include <ctype.h>
namespace SkSL {
std::string Mangler::uniqueName(std::string_view baseName, SymbolTable* symbolTable) {
SkASSERT(symbolTable);
// Private names might begin with a $. Strip that off.
if (skstd::starts_with(baseName, '$')) {
baseName.remove_prefix(1);
}
// The inliner runs more than once, so the base name might already have been mangled and have a
// prefix like "_123_x". Let's strip that prefix off to make the generated code easier to read.
if (skstd::starts_with(baseName, '_')) {
// Determine if we have a string of digits.
int offset = 1;
while (isdigit(baseName[offset])) {
++offset;
}
// If we found digits, another underscore, and anything else, that's the mangler prefix.
// Strip it off.
if (offset > 1 && baseName[offset] == '_' && baseName[offset + 1] != '\0') {
baseName.remove_prefix(offset + 1);
} else {
// This name doesn't contain a mangler prefix, but it does start with an underscore.
// OpenGL disallows two consecutive underscores anywhere in the string, and we'll be
// adding one as part of the mangler prefix, so strip the leading underscore.
baseName.remove_prefix(1);
}
}
// Append a unique numeric prefix to avoid name overlap. Check the symbol table to make sure
// we're not reusing an existing name. (Note that within a single compilation pass, this check
// isn't fully comprehensive, as code isn't always generated in top-to-bottom order.)
// This code is a performance hotspot. Assemble the string manually to save a few cycles.
char uniqueName[256];
uniqueName[0] = '_';
char* uniqueNameEnd = uniqueName + SK_ARRAY_COUNT(uniqueName);
for (;;) {
// _123
char* endPtr = SkStrAppendS32(uniqueName + 1, fCounter++);
// _123_
*endPtr++ = '_';
// _123_baseNameTruncatedToFit (no null terminator, because string_view doesn't require one)
int baseNameCopyLength = std::min<int>(baseName.size(), uniqueNameEnd - endPtr);
memcpy(endPtr, baseName.data(), baseNameCopyLength);
endPtr += baseNameCopyLength;
std::string_view uniqueNameView(uniqueName, endPtr - uniqueName);
if ((*symbolTable)[uniqueNameView] == nullptr) {
return std::string(uniqueNameView);
}
}
}
} // namespace SkSL