| /* |
| * 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 |