1 /*
2 * Copyright 2022 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 "include/core/SkTypes.h"
9 #include "src/core/SkTHash.h"
10 #include "src/sksl/SkSLContext.h"
11 #include "src/sksl/SkSLIntrinsicList.h"
12 #include "src/sksl/SkSLProgramSettings.h"
13 #include "src/sksl/analysis/SkSLProgramUsage.h"
14 #include "src/sksl/ir/SkSLFunctionDeclaration.h"
15 #include "src/sksl/ir/SkSLFunctionDefinition.h"
16 #include "src/sksl/ir/SkSLProgram.h"
17 #include "src/sksl/transform/SkSLTransform.h"
18
19 #include <algorithm>
20 #include <cstddef>
21 #include <memory>
22 #include <string>
23 #include <string_view>
24 #include <vector>
25
26 namespace SkSL {
27
28 class ProgramElement;
29
FindAndDeclareBuiltinFunctions(Program & program)30 void Transform::FindAndDeclareBuiltinFunctions(Program& program) {
31 ProgramUsage* usage = program.fUsage.get();
32 Context& context = *program.fContext;
33
34 std::vector<const FunctionDefinition*> addedBuiltins;
35 for (;;) {
36 // Find all the built-ins referenced by the program but not yet included in the code.
37 size_t numBuiltinsAtStart = addedBuiltins.size();
38 for (const auto& [fn, count] : usage->fCallCounts) {
39 if (!fn->isBuiltin() || count == 0) {
40 // Not a built-in; skip it.
41 continue;
42 }
43 if (fn->intrinsicKind() == k_dFdy_IntrinsicKind) {
44 // Programs that invoke the `dFdy` intrinsic will need the RTFlip input.
45 program.fInputs.fUseFlipRTUniform = !context.fConfig->fSettings.fForceNoRTFlip;
46 }
47 if (const FunctionDefinition* builtinDef = fn->definition()) {
48 // Make sure we only add a built-in function once. We rarely add more than a handful
49 // of builtin functions, so linear search here is good enough.
50 if (std::find(addedBuiltins.begin(), addedBuiltins.end(), builtinDef) ==
51 addedBuiltins.end()) {
52 addedBuiltins.push_back(builtinDef);
53 }
54 }
55 }
56
57 if (addedBuiltins.size() == numBuiltinsAtStart) {
58 // If we didn't reference any more built-in functions than before, we're done.
59 break;
60 }
61
62 // Sort the referenced builtin functions into a consistent order; otherwise our output will
63 // become non-deterministic. The exact order isn't particularly important; we sort backwards
64 // because we add elements to the shared-elements in reverse order at the end.
65 std::sort(addedBuiltins.begin() + numBuiltinsAtStart,
66 addedBuiltins.end(),
67 [](const FunctionDefinition* aDefinition, const FunctionDefinition* bDefinition) {
68 const FunctionDeclaration& a = aDefinition->declaration();
69 const FunctionDeclaration& b = bDefinition->declaration();
70 if (a.name() != b.name()) {
71 return a.name() > b.name();
72 }
73 return a.description() > b.description();
74 });
75
76 // Update the ProgramUsage to track all these newly discovered functions.
77 int usageCallCounts = usage->fCallCounts.count();
78
79 for (size_t index = numBuiltinsAtStart; index < addedBuiltins.size(); ++index) {
80 usage->add(*addedBuiltins[index]);
81 }
82
83 if (usage->fCallCounts.count() == usageCallCounts) {
84 // If we aren't making any more unique function calls than before, we're done.
85 break;
86 }
87 }
88
89 // Insert the new functions into the program's shared elements, right at the front.
90 // They are added in reverse so that the deepest dependencies are added to the top.
91 program.fSharedElements.insert(program.fSharedElements.begin(),
92 addedBuiltins.rbegin(), addedBuiltins.rend());
93 }
94
95 } // namespace SkSL
96