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https://github.com/KhronosGroup/SPIRV-Tools
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Do not fold mul and adds to generate fmas (#5682)
This removes the folding rules added in #4783 and #4808. They lead to poor code generation on Adreno devices when 16-bit floating point values were used. Since this change is transformation is suppose to be neutral, there is no general reason to continue doing it. I have talked to the owners of SwiftShader, and they do not mind if the transform is removed. They were the ones the requested the change in the first place. Fixes #5658
This commit is contained in:
Steven Perron
GitHub
parent
ee749f5057
commit
336b5710a5
@ -1459,132 +1459,6 @@ FoldingRule FactorAddMuls() {
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};
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}
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// Replaces |inst| inplace with an FMA instruction |(x*y)+a|.
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void ReplaceWithFma(Instruction* inst, uint32_t x, uint32_t y, uint32_t a) {
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uint32_t ext =
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inst->context()->get_feature_mgr()->GetExtInstImportId_GLSLstd450();
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if (ext == 0) {
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inst->context()->AddExtInstImport("GLSL.std.450");
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ext = inst->context()->get_feature_mgr()->GetExtInstImportId_GLSLstd450();
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assert(ext != 0 &&
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"Could not add the GLSL.std.450 extended instruction set");
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}
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std::vector<Operand> operands;
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operands.push_back({SPV_OPERAND_TYPE_ID, {ext}});
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operands.push_back({SPV_OPERAND_TYPE_LITERAL_INTEGER, {GLSLstd450Fma}});
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operands.push_back({SPV_OPERAND_TYPE_ID, {x}});
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operands.push_back({SPV_OPERAND_TYPE_ID, {y}});
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operands.push_back({SPV_OPERAND_TYPE_ID, {a}});
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inst->SetOpcode(spv::Op::OpExtInst);
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inst->SetInOperands(std::move(operands));
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}
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// Folds a multiple and add into an Fma.
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//
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// Cases:
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// (x * y) + a = Fma x y a
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// a + (x * y) = Fma x y a
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bool MergeMulAddArithmetic(IRContext* context, Instruction* inst,
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const std::vector<const analysis::Constant*>&) {
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assert(inst->opcode() == spv::Op::OpFAdd);
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if (!inst->IsFloatingPointFoldingAllowed()) {
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return false;
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}
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analysis::DefUseManager* def_use_mgr = context->get_def_use_mgr();
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for (int i = 0; i < 2; i++) {
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uint32_t op_id = inst->GetSingleWordInOperand(i);
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Instruction* op_inst = def_use_mgr->GetDef(op_id);
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if (op_inst->opcode() != spv::Op::OpFMul) {
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continue;
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}
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if (!op_inst->IsFloatingPointFoldingAllowed()) {
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continue;
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}
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uint32_t x = op_inst->GetSingleWordInOperand(0);
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uint32_t y = op_inst->GetSingleWordInOperand(1);
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uint32_t a = inst->GetSingleWordInOperand((i + 1) % 2);
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ReplaceWithFma(inst, x, y, a);
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return true;
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}
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return false;
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}
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// Replaces |sub| inplace with an FMA instruction |(x*y)+a| where |a| first gets
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// negated if |negate_addition| is true, otherwise |x| gets negated.
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void ReplaceWithFmaAndNegate(Instruction* sub, uint32_t x, uint32_t y,
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uint32_t a, bool negate_addition) {
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uint32_t ext =
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sub->context()->get_feature_mgr()->GetExtInstImportId_GLSLstd450();
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if (ext == 0) {
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sub->context()->AddExtInstImport("GLSL.std.450");
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ext = sub->context()->get_feature_mgr()->GetExtInstImportId_GLSLstd450();
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assert(ext != 0 &&
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"Could not add the GLSL.std.450 extended instruction set");
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}
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InstructionBuilder ir_builder(
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sub->context(), sub,
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IRContext::kAnalysisDefUse | IRContext::kAnalysisInstrToBlockMapping);
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Instruction* neg = ir_builder.AddUnaryOp(sub->type_id(), spv::Op::OpFNegate,
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negate_addition ? a : x);
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uint32_t neg_op = neg->result_id(); // -a : -x
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std::vector<Operand> operands;
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operands.push_back({SPV_OPERAND_TYPE_ID, {ext}});
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operands.push_back({SPV_OPERAND_TYPE_LITERAL_INTEGER, {GLSLstd450Fma}});
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operands.push_back({SPV_OPERAND_TYPE_ID, {negate_addition ? x : neg_op}});
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operands.push_back({SPV_OPERAND_TYPE_ID, {y}});
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operands.push_back({SPV_OPERAND_TYPE_ID, {negate_addition ? neg_op : a}});
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sub->SetOpcode(spv::Op::OpExtInst);
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sub->SetInOperands(std::move(operands));
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}
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// Folds a multiply and subtract into an Fma and negation.
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//
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// Cases:
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// (x * y) - a = Fma x y -a
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// a - (x * y) = Fma -x y a
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bool MergeMulSubArithmetic(IRContext* context, Instruction* sub,
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const std::vector<const analysis::Constant*>&) {
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assert(sub->opcode() == spv::Op::OpFSub);
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if (!sub->IsFloatingPointFoldingAllowed()) {
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return false;
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}
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analysis::DefUseManager* def_use_mgr = context->get_def_use_mgr();
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for (int i = 0; i < 2; i++) {
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uint32_t op_id = sub->GetSingleWordInOperand(i);
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Instruction* mul = def_use_mgr->GetDef(op_id);
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if (mul->opcode() != spv::Op::OpFMul) {
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continue;
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}
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if (!mul->IsFloatingPointFoldingAllowed()) {
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continue;
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}
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uint32_t x = mul->GetSingleWordInOperand(0);
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uint32_t y = mul->GetSingleWordInOperand(1);
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uint32_t a = sub->GetSingleWordInOperand((i + 1) % 2);
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ReplaceWithFmaAndNegate(sub, x, y, a, i == 0);
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return true;
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}
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return false;
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}
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FoldingRule IntMultipleBy1() {
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return [](IRContext*, Instruction* inst,
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const std::vector<const analysis::Constant*>& constants) {
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@ -2941,7 +2815,6 @@ void FoldingRules::AddFoldingRules() {
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rules_[spv::Op::OpFAdd].push_back(MergeAddSubArithmetic());
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rules_[spv::Op::OpFAdd].push_back(MergeGenericAddSubArithmetic());
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rules_[spv::Op::OpFAdd].push_back(FactorAddMuls());
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rules_[spv::Op::OpFAdd].push_back(MergeMulAddArithmetic);
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rules_[spv::Op::OpFDiv].push_back(RedundantFDiv());
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rules_[spv::Op::OpFDiv].push_back(ReciprocalFDiv());
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@ -2962,7 +2835,6 @@ void FoldingRules::AddFoldingRules() {
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rules_[spv::Op::OpFSub].push_back(MergeSubNegateArithmetic());
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rules_[spv::Op::OpFSub].push_back(MergeSubAddArithmetic());
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rules_[spv::Op::OpFSub].push_back(MergeSubSubArithmetic());
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rules_[spv::Op::OpFSub].push_back(MergeMulSubArithmetic);
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rules_[spv::Op::OpIAdd].push_back(RedundantIAdd());
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rules_[spv::Op::OpIAdd].push_back(MergeAddNegateArithmetic());
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@ -7933,21 +7933,15 @@ INSTANTIATE_TEST_SUITE_P(VectorShuffleMatchingTest, MatchingInstructionFoldingTe
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3, true)
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));
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// Issue #5658: The Adreno compiler does not handle 16-bit FMA instructions well.
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// We want to avoid this by not generating FMA. We decided to never generate
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// FMAs because, from a SPIR-V perspective, it is neutral. The ICD can generate
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// the FMA if it wants. The simplest code is no code.
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INSTANTIATE_TEST_SUITE_P(FmaGenerationMatchingTest, MatchingInstructionFoldingTest,
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::testing::Values(
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// Test case 0: (x * y) + a = Fma(x, y, a)
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// Test case 0: Don't fold (x * y) + a
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InstructionFoldingCase<bool>(
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Header() +
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"; CHECK: [[ext:%\\w+]] = OpExtInstImport \"GLSL.std.450\"\n" +
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"; CHECK: OpFunction\n" +
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"; CHECK: [[x:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[y:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[a:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[lx:%\\w+]] = OpLoad {{%\\w+}} [[x]]\n" +
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"; CHECK: [[ly:%\\w+]] = OpLoad {{%\\w+}} [[y]]\n" +
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"; CHECK: [[la:%\\w+]] = OpLoad {{%\\w+}} [[a]]\n" +
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"; CHECK: [[fma:%\\w+]] = OpExtInst {{%\\w+}} [[ext]] Fma [[lx]] [[ly]] [[la]]\n" +
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"; CHECK: OpStore {{%\\w+}} [[fma]]\n" +
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"%main = OpFunction %void None %void_func\n" +
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"%main_lab = OpLabel\n" +
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"%x = OpVariable %_ptr_float Function\n" +
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@ -7961,20 +7955,10 @@ INSTANTIATE_TEST_SUITE_P(FmaGenerationMatchingTest, MatchingInstructionFoldingTe
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"OpStore %a %3\n" +
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"OpReturn\n" +
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"OpFunctionEnd",
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3, true),
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// Test case 1: a + (x * y) = Fma(x, y, a)
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3, false),
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// Test case 1: Don't fold a + (x * y)
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InstructionFoldingCase<bool>(
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Header() +
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"; CHECK: [[ext:%\\w+]] = OpExtInstImport \"GLSL.std.450\"\n" +
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"; CHECK: OpFunction\n" +
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"; CHECK: [[x:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[y:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[a:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[lx:%\\w+]] = OpLoad {{%\\w+}} [[x]]\n" +
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"; CHECK: [[ly:%\\w+]] = OpLoad {{%\\w+}} [[y]]\n" +
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"; CHECK: [[la:%\\w+]] = OpLoad {{%\\w+}} [[a]]\n" +
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"; CHECK: [[fma:%\\w+]] = OpExtInst {{%\\w+}} [[ext]] Fma [[lx]] [[ly]] [[la]]\n" +
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"; CHECK: OpStore {{%\\w+}} [[fma]]\n" +
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"%main = OpFunction %void None %void_func\n" +
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"%main_lab = OpLabel\n" +
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"%x = OpVariable %_ptr_float Function\n" +
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@ -7988,20 +7972,10 @@ INSTANTIATE_TEST_SUITE_P(FmaGenerationMatchingTest, MatchingInstructionFoldingTe
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"OpStore %a %3\n" +
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"OpReturn\n" +
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"OpFunctionEnd",
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3, true),
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// Test case 2: (x * y) + a = Fma(x, y, a) with vectors
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3, false),
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// Test case 2: Don't fold (x * y) + a with vectors
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InstructionFoldingCase<bool>(
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Header() +
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"; CHECK: [[ext:%\\w+]] = OpExtInstImport \"GLSL.std.450\"\n" +
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"; CHECK: OpFunction\n" +
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"; CHECK: [[x:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[y:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[a:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[lx:%\\w+]] = OpLoad {{%\\w+}} [[x]]\n" +
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"; CHECK: [[ly:%\\w+]] = OpLoad {{%\\w+}} [[y]]\n" +
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"; CHECK: [[la:%\\w+]] = OpLoad {{%\\w+}} [[a]]\n" +
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"; CHECK: [[fma:%\\w+]] = OpExtInst {{%\\w+}} [[ext]] Fma [[lx]] [[ly]] [[la]]\n" +
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"; CHECK: OpStore {{%\\w+}} [[fma]]\n" +
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"%main = OpFunction %void None %void_func\n" +
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"%main_lab = OpLabel\n" +
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"%x = OpVariable %_ptr_v4float Function\n" +
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@ -8015,20 +7989,10 @@ INSTANTIATE_TEST_SUITE_P(FmaGenerationMatchingTest, MatchingInstructionFoldingTe
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"OpStore %a %3\n" +
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"OpReturn\n" +
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"OpFunctionEnd",
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3, true),
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// Test case 3: a + (x * y) = Fma(x, y, a) with vectors
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3,false),
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// Test case 3: Don't fold a + (x * y) with vectors
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InstructionFoldingCase<bool>(
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Header() +
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"; CHECK: [[ext:%\\w+]] = OpExtInstImport \"GLSL.std.450\"\n" +
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"; CHECK: OpFunction\n" +
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"; CHECK: [[x:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[y:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[a:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[lx:%\\w+]] = OpLoad {{%\\w+}} [[x]]\n" +
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"; CHECK: [[ly:%\\w+]] = OpLoad {{%\\w+}} [[y]]\n" +
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"; CHECK: [[la:%\\w+]] = OpLoad {{%\\w+}} [[a]]\n" +
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"; CHECK: [[fma:%\\w+]] = OpExtInst {{%\\w+}} [[ext]] Fma [[lx]] [[ly]] [[la]]\n" +
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"; CHECK: OpStore {{%\\w+}} [[fma]]\n" +
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"%main = OpFunction %void None %void_func\n" +
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"%main_lab = OpLabel\n" +
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"%x = OpVariable %_ptr_float Function\n" +
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@ -8042,46 +8006,8 @@ INSTANTIATE_TEST_SUITE_P(FmaGenerationMatchingTest, MatchingInstructionFoldingTe
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"OpStore %a %3\n" +
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"OpReturn\n" +
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"OpFunctionEnd",
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3, true),
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// Test 4: that the OpExtInstImport instruction is generated if it is missing.
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InstructionFoldingCase<bool>(
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std::string() +
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"; CHECK: [[ext:%\\w+]] = OpExtInstImport \"GLSL.std.450\"\n" +
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"; CHECK: OpFunction\n" +
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"; CHECK: [[x:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[y:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[a:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[lx:%\\w+]] = OpLoad {{%\\w+}} [[x]]\n" +
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"; CHECK: [[ly:%\\w+]] = OpLoad {{%\\w+}} [[y]]\n" +
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"; CHECK: [[la:%\\w+]] = OpLoad {{%\\w+}} [[a]]\n" +
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"; CHECK: [[fma:%\\w+]] = OpExtInst {{%\\w+}} [[ext]] Fma [[lx]] [[ly]] [[la]]\n" +
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"; CHECK: OpStore {{%\\w+}} [[fma]]\n" +
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"OpCapability Shader\n" +
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"OpMemoryModel Logical GLSL450\n" +
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"OpEntryPoint Fragment %main \"main\"\n" +
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"OpExecutionMode %main OriginUpperLeft\n" +
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"OpSource GLSL 140\n" +
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"OpName %main \"main\"\n" +
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"%void = OpTypeVoid\n" +
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"%void_func = OpTypeFunction %void\n" +
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"%bool = OpTypeBool\n" +
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"%float = OpTypeFloat 32\n" +
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"%_ptr_float = OpTypePointer Function %float\n" +
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"%main = OpFunction %void None %void_func\n" +
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"%main_lab = OpLabel\n" +
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"%x = OpVariable %_ptr_float Function\n" +
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"%y = OpVariable %_ptr_float Function\n" +
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"%a = OpVariable %_ptr_float Function\n" +
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"%lx = OpLoad %float %x\n" +
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"%ly = OpLoad %float %y\n" +
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"%mul = OpFMul %float %lx %ly\n" +
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"%la = OpLoad %float %a\n" +
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"%3 = OpFAdd %float %mul %la\n" +
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"OpStore %a %3\n" +
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"OpReturn\n" +
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"OpFunctionEnd",
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3, true),
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// Test 5: Don't fold if the multiple is marked no contract.
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3, false),
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// Test 4: Don't fold if the multiple is marked no contract.
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InstructionFoldingCase<bool>(
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std::string() +
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"OpCapability Shader\n" +
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@ -8110,7 +8036,7 @@ INSTANTIATE_TEST_SUITE_P(FmaGenerationMatchingTest, MatchingInstructionFoldingTe
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"OpReturn\n" +
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"OpFunctionEnd",
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3, false),
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// Test 6: Don't fold if the add is marked no contract.
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// Test 5: Don't fold if the add is marked no contract.
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InstructionFoldingCase<bool>(
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std::string() +
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"OpCapability Shader\n" +
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@ -8139,20 +8065,9 @@ INSTANTIATE_TEST_SUITE_P(FmaGenerationMatchingTest, MatchingInstructionFoldingTe
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"OpReturn\n" +
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"OpFunctionEnd",
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3, false),
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// Test case 7: (x * y) - a = Fma(x, y, -a)
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// Test case 6: Don't fold (x * y) - a
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InstructionFoldingCase<bool>(
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Header() +
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"; CHECK: [[ext:%\\w+]] = OpExtInstImport \"GLSL.std.450\"\n" +
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"; CHECK: OpFunction\n" +
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"; CHECK: [[x:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[y:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[a:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[lx:%\\w+]] = OpLoad {{%\\w+}} [[x]]\n" +
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"; CHECK: [[ly:%\\w+]] = OpLoad {{%\\w+}} [[y]]\n" +
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"; CHECK: [[la:%\\w+]] = OpLoad {{%\\w+}} [[a]]\n" +
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"; CHECK: [[na:%\\w+]] = OpFNegate {{%\\w+}} [[la]]\n" +
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"; CHECK: [[fma:%\\w+]] = OpExtInst {{%\\w+}} [[ext]] Fma [[lx]] [[ly]] [[na]]\n" +
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"; CHECK: OpStore {{%\\w+}} [[fma]]\n" +
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"%main = OpFunction %void None %void_func\n" +
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"%main_lab = OpLabel\n" +
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"%x = OpVariable %_ptr_float Function\n" +
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@ -8166,21 +8081,10 @@ INSTANTIATE_TEST_SUITE_P(FmaGenerationMatchingTest, MatchingInstructionFoldingTe
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"OpStore %a %3\n" +
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"OpReturn\n" +
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"OpFunctionEnd",
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3, true),
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// Test case 8: a - (x * y) = Fma(-x, y, a)
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3, false),
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// Test case 7: Don't fold a - (x * y)
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InstructionFoldingCase<bool>(
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Header() +
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"; CHECK: [[ext:%\\w+]] = OpExtInstImport \"GLSL.std.450\"\n" +
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"; CHECK: OpFunction\n" +
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"; CHECK: [[x:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[y:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[a:%\\w+]] = OpVariable {{%\\w+}} Function\n" +
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"; CHECK: [[lx:%\\w+]] = OpLoad {{%\\w+}} [[x]]\n" +
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"; CHECK: [[ly:%\\w+]] = OpLoad {{%\\w+}} [[y]]\n" +
|
||||
"; CHECK: [[la:%\\w+]] = OpLoad {{%\\w+}} [[a]]\n" +
|
||||
"; CHECK: [[nx:%\\w+]] = OpFNegate {{%\\w+}} [[lx]]\n" +
|
||||
"; CHECK: [[fma:%\\w+]] = OpExtInst {{%\\w+}} [[ext]] Fma [[nx]] [[ly]] [[la]]\n" +
|
||||
"; CHECK: OpStore {{%\\w+}} [[fma]]\n" +
|
||||
"%main = OpFunction %void None %void_func\n" +
|
||||
"%main_lab = OpLabel\n" +
|
||||
"%x = OpVariable %_ptr_float Function\n" +
|
||||
@ -8194,7 +8098,7 @@ INSTANTIATE_TEST_SUITE_P(FmaGenerationMatchingTest, MatchingInstructionFoldingTe
|
||||
"OpStore %a %3\n" +
|
||||
"OpReturn\n" +
|
||||
"OpFunctionEnd",
|
||||
3, true)
|
||||
3, false)
|
||||
));
|
||||
|
||||
using MatchingInstructionWithNoResultFoldingTest =
|
||||
|
||||
Loading…
Reference in New Issue
Block a user