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Generalize assert in ccp (#4735)

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CCP does not want to fold an instruction unless it folds to a constant.
There is an asser to check for this.  The question if a spec constant
counts as a constant.  The constant folder considers a spec constant a
constand, but CCP does not.  I've fixed the assert in CCP to match what
the folder does.  It should not require any new changes to CCP.
This commit is contained in:
Steven Perron 2022-03-07 19:33:10 +00:00 committed by GitHub
parent 196f638d73
commit 4fa1a6f9b4
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2 changed files with 31 additions and 1 deletions
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3
source/opt/ccp_pass.cpp
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@ -172,7 +172,8 @@ SSAPropagator::PropStatus CCPPass::VisitAssignment(Instruction* instr) {
if (folded_inst != nullptr) {
// We do not want to change the body of the function by adding new
// instructions. When folding we can only generate new constants.
assert(folded_inst->IsConstant() &&
assert((folded_inst->IsConstant() ||
IsSpecConstantInst(folded_inst->opcode())) &&
"CCP is only interested in constant values.");
uint32_t new_val = ComputeLatticeMeet(instr, folded_inst->result_id());
values_[instr->result_id()] = new_val;

29
test/opt/ccp_test.cpp
View File

@ -582,6 +582,35 @@ TEST_F(CCPTest, SkipSpecConstantInstrucitons) {
EXPECT_EQ(std::get<1>(res), Pass::Status::SuccessWithoutChange);
}
TEST_F(CCPTest, FoldConstantCompositeInstrucitonsWithSpecConst) {
const std::string spv_asm = R"(
OpCapability Shader
OpMemoryModel Logical GLSL450
OpEntryPoint Fragment %1 "main"
OpExecutionMode %1 OriginUpperLeft
%void = OpTypeVoid
%4 = OpTypeFunction %void
%bool = OpTypeBool
%v3bool = OpTypeVector %bool 3
%_struct_8 = OpTypeStruct %v3bool
%true = OpConstantTrue %bool
; CHECK: [[spec_const:%\w+]] = OpSpecConstantComposite %v3bool
%11 = OpSpecConstantComposite %v3bool %true %true %true
%12 = OpConstantComposite %_struct_8 %11
; CHECK: OpFunction
%1 = OpFunction %void None %4
%29 = OpLabel
%31 = OpCompositeExtract %v3bool %12 0
; CHECK: OpCompositeExtract %bool [[spec_const]] 0
%32 = OpCompositeExtract %bool %31 0
OpReturn
OpFunctionEnd
)";
auto result = SinglePassRunAndMatch<CCPPass>(spv_asm, true);
EXPECT_EQ(std::get<1>(result), Pass::Status::SuccessWithChange);
}
TEST_F(CCPTest, UpdateSubsequentPhisToVarying) {
const std::string text = R"(
OpCapability Shader