1 /*
2 * Copyright 2021 Google LLC.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #include "src/sksl/SkSLMangler.h"
9 #include "src/sksl/ir/SkSLSymbolTable.h"
10
11 namespace SkSL {
12
uniqueName(String baseName,SymbolTable * symbolTable)13 String Mangler::uniqueName(String baseName, SymbolTable* symbolTable) {
14 SkASSERT(symbolTable);
15 // The inliner runs more than once, so the base name might already have been mangled and have a
16 // prefix like "_123_x". Let's strip that prefix off to make the generated code easier to read.
17 if (baseName.startsWith("_")) {
18 // Determine if we have a string of digits.
19 int offset = 1;
20 while (isdigit(baseName[offset])) {
21 ++offset;
22 }
23 // If we found digits, another underscore, and anything else, that's the mangler prefix.
24 // Strip it off.
25 if (offset > 1 && baseName[offset] == '_' && baseName[offset + 1] != '\0') {
26 baseName.erase(0, offset + 1);
27 } else {
28 // This name doesn't contain a mangler prefix, but it does start with an underscore.
29 // OpenGL disallows two consecutive underscores anywhere in the string, and we'll be
30 // adding one as part of the mangler prefix, so strip the leading underscore.
31 baseName.erase(0, 1);
32 }
33 }
34
35 // Append a unique numeric prefix to avoid name overlap. Check the symbol table to make sure
36 // we're not reusing an existing name. (Note that within a single compilation pass, this check
37 // isn't fully comprehensive, as code isn't always generated in top-to-bottom order.)
38 String uniqueName;
39 for (;;) {
40 uniqueName = String::printf("_%d_%s", fCounter++, baseName.c_str());
41 StringFragment frag{uniqueName.data(), uniqueName.length()};
42 if ((*symbolTable)[frag] == nullptr) {
43 break;
44 }
45 }
46
47 return uniqueName;
48 }
49
50 } // namespace SkSL
51