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https://github.com/KhronosGroup/SPIRV-Tools
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spirv-fuzz: Fix handling of OpPhi in FlattenConditionalBranch (#3916)
Fixes #3915.
This commit is contained in:
Alastair Donaldson
GitHub
parent
5c64374dd6
commit
53aeba10cd
@ -145,16 +145,8 @@ void TransformationFlattenConditionalBranch::Apply(
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current_block->terminator()->GetSingleWordInOperand(0);
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}
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// Get the mapping from instructions to fresh ids.
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auto insts_to_info = GetInstructionsToWrapperInfo(ir_context);
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auto branch_instruction = header_block->terminator();
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// Get a reference to the last block in the first branch that will be laid out
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// (this depends on |message_.true_branch_first|). The last block is the block
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// in the branch just before flow converges (it might not exist).
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opt::BasicBlock* last_block_first_branch = nullptr;
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// branch = 1 corresponds to the true branch, branch = 2 corresponds to the
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// false branch. If the true branch is to be laid out first, we need to visit
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// the false branch first, because each branch is moved to right after the
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@ -166,6 +158,68 @@ void TransformationFlattenConditionalBranch::Apply(
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branches = {1, 2};
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}
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// Get the ids of the starting blocks of the first and last branches to be
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// laid out. The first branch is the true branch iff
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// |message_.true_branch_first| is true.
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uint32_t first_block_first_branch_id =
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branch_instruction->GetSingleWordInOperand(branches[1]);
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uint32_t first_block_last_branch_id =
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branch_instruction->GetSingleWordInOperand(branches[0]);
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// If the OpBranchConditional instruction in the header branches to the same
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// block for both values of the condition, this is the convergence block (the
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// flow does not actually diverge) and the OpPhi instructions in it are still
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// valid, so we do not need to make any changes.
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if (first_block_first_branch_id != first_block_last_branch_id) {
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// Replace all of the current OpPhi instructions in the convergence block
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// with OpSelect.
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ir_context->get_instr_block(convergence_block_id)
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->ForEachPhiInst([branch_instruction, header_block,
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ir_context](opt::Instruction* phi_inst) {
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assert(phi_inst->NumInOperands() == 4 &&
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"We are going to replace an OpPhi with an OpSelect. This "
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"only makes sense if the block has two distinct "
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"predecessors.");
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// The OpPhi takes values from two distinct predecessors. One
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// predecessor is associated with the "true" path of the conditional
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// we are flattening, the other with the "false" path, but these
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// predecessors can appear in either order as operands to the OpPhi
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// instruction.
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std::vector<opt::Operand> operands;
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operands.emplace_back(branch_instruction->GetInOperand(0));
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uint32_t branch_instruction_true_block_id =
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branch_instruction->GetSingleWordInOperand(1);
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if (ir_context->GetDominatorAnalysis(header_block->GetParent())
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->Dominates(branch_instruction_true_block_id,
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phi_inst->GetSingleWordInOperand(1))) {
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// The "true" branch is handled first in the OpPhi's operands; we
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// thus provide operands to OpSelect in the same order that they
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// appear in the OpPhi.
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operands.emplace_back(phi_inst->GetInOperand(0));
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operands.emplace_back(phi_inst->GetInOperand(2));
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} else {
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// The "false" branch is handled first in the OpPhi's operands; we
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// thus provide operands to OpSelect in reverse of the order that
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// they appear in the OpPhi.
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operands.emplace_back(phi_inst->GetInOperand(2));
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operands.emplace_back(phi_inst->GetInOperand(0));
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}
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phi_inst->SetOpcode(SpvOpSelect);
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phi_inst->SetInOperands(std::move(operands));
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});
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}
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// Get the mapping from instructions to fresh ids.
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auto insts_to_info = GetInstructionsToWrapperInfo(ir_context);
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// Get a reference to the last block in the first branch that will be laid out
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// (this depends on |message_.true_branch_first|). The last block is the block
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// in the branch just before flow converges (it might not exist).
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opt::BasicBlock* last_block_first_branch = nullptr;
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// Keep track of blocks and ids for which we should later add dead block and
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// irrelevant id facts. We wait until we have finished applying the
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// transformation before adding these facts, so that the fact manager has
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@ -271,21 +325,6 @@ void TransformationFlattenConditionalBranch::Apply(
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}
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}
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// Get the condition operand and the ids of the starting blocks of the first
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// and last branches to be laid out. The first branch is the true branch iff
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// |message_.true_branch_first| is true.
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auto condition_operand = branch_instruction->GetInOperand(0);
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uint32_t first_block_first_branch_id =
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branch_instruction->GetSingleWordInOperand(branches[1]);
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uint32_t first_block_last_branch_id =
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branch_instruction->GetSingleWordInOperand(branches[0]);
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// Record the block that will be reached if the branch condition is true.
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// This information is needed later to determine how to rewrite OpPhi
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// instructions as OpSelect instructions at the branch's convergence point.
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uint32_t branch_instruction_true_block_id =
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branch_instruction->GetSingleWordInOperand(1);
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// The current header should unconditionally branch to the starting block in
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// the first branch to be laid out, if such a branch exists (i.e. the header
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// does not branch directly to the convergence block), and to the starting
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@ -330,51 +369,6 @@ void TransformationFlattenConditionalBranch::Apply(
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}
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}
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// If the OpBranchConditional instruction in the header branches to the same
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// block for both values of the condition, this is the convergence block (the
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// flow does not actually diverge) and the OpPhi instructions in it are still
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// valid, so we do not need to make any changes.
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if (first_block_first_branch_id != first_block_last_branch_id) {
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// Replace all of the current OpPhi instructions in the convergence block
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// with OpSelect.
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ir_context->get_instr_block(convergence_block_id)
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->ForEachPhiInst([branch_instruction_true_block_id, &condition_operand,
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header_block,
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ir_context](opt::Instruction* phi_inst) {
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assert(phi_inst->NumInOperands() == 4 &&
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"We are going to replace an OpPhi with an OpSelect. This "
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"only makes sense if the block has two distinct "
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"predecessors.");
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// The OpPhi takes values from two distinct predecessors. One
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// predecessor is associated with the "true" path of the conditional
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// we are flattening, the other with the "false" path, but these
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// predecessors can appear in either order as operands to the OpPhi
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// instruction.
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std::vector<opt::Operand> operands;
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operands.emplace_back(condition_operand);
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if (ir_context->GetDominatorAnalysis(header_block->GetParent())
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->Dominates(branch_instruction_true_block_id,
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phi_inst->GetSingleWordInOperand(1))) {
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// The "true" branch is handled first in the OpPhi's operands; we
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// thus provide operands to OpSelect in the same order that they
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// appear in the OpPhi.
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operands.emplace_back(phi_inst->GetInOperand(0));
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operands.emplace_back(phi_inst->GetInOperand(2));
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} else {
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// The "false" branch is handled first in the OpPhi's operands; we
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// thus provide operands to OpSelect in reverse of the order that
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// they appear in the OpPhi.
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operands.emplace_back(phi_inst->GetInOperand(2));
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operands.emplace_back(phi_inst->GetInOperand(0));
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}
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phi_inst->SetOpcode(SpvOpSelect);
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phi_inst->SetInOperands(std::move(operands));
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});
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}
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// Invalidate all analyses
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ir_context->InvalidateAnalysesExceptFor(opt::IRContext::kAnalysisNone);
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@ -1066,6 +1066,108 @@ TEST(TransformationFlattenConditionalBranchTest, PhiToSelect4) {
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ASSERT_TRUE(IsEqual(env, after_transformation, context.get()));
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}
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TEST(TransformationFlattenConditionalBranchTest, PhiToSelect5) {
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std::string shader = R"(
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OpCapability Shader
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%1 = OpExtInstImport "GLSL.std.450"
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OpMemoryModel Logical GLSL450
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OpEntryPoint Fragment %2 "main"
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OpExecutionMode %2 OriginUpperLeft
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OpSource ESSL 310
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%3 = OpTypeVoid
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%4 = OpTypeBool
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%5 = OpConstantTrue %4
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%10 = OpConstantFalse %4
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%6 = OpTypeFunction %3
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%100 = OpTypePointer Function %4
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%2 = OpFunction %3 None %6
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%7 = OpLabel
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%101 = OpVariable %100 Function
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%102 = OpVariable %100 Function
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OpSelectionMerge %470 None
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OpBranchConditional %5 %454 %462
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%454 = OpLabel
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%522 = OpLoad %4 %101
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OpBranch %470
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%462 = OpLabel
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%466 = OpLoad %4 %102
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OpBranch %470
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%470 = OpLabel
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%534 = OpPhi %4 %522 %454 %466 %462
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OpReturn
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OpFunctionEnd
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)";
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const auto env = SPV_ENV_UNIVERSAL_1_5;
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const auto consumer = nullptr;
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const auto context = BuildModule(env, consumer, shader, kFuzzAssembleOption);
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ASSERT_TRUE(IsValid(env, context.get()));
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spvtools::ValidatorOptions validator_options;
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TransformationContext transformation_context(
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MakeUnique<FactManager>(context.get()), validator_options);
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auto transformation = TransformationFlattenConditionalBranch(
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7, true,
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{MakeSideEffectWrapperInfo(MakeInstructionDescriptor(522, SpvOpLoad, 0),
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200, 201, 202, 203, 204, 5),
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MakeSideEffectWrapperInfo(MakeInstructionDescriptor(466, SpvOpLoad, 0),
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300, 301, 302, 303, 304, 5)});
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ASSERT_TRUE(
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transformation.IsApplicable(context.get(), transformation_context));
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ApplyAndCheckFreshIds(transformation, context.get(), &transformation_context);
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ASSERT_TRUE(IsValid(env, context.get()));
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std::string after_transformation = R"(
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OpCapability Shader
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%1 = OpExtInstImport "GLSL.std.450"
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OpMemoryModel Logical GLSL450
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OpEntryPoint Fragment %2 "main"
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OpExecutionMode %2 OriginUpperLeft
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OpSource ESSL 310
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%3 = OpTypeVoid
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%4 = OpTypeBool
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%5 = OpConstantTrue %4
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%10 = OpConstantFalse %4
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%6 = OpTypeFunction %3
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%100 = OpTypePointer Function %4
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%2 = OpFunction %3 None %6
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%7 = OpLabel
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%101 = OpVariable %100 Function
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%102 = OpVariable %100 Function
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OpBranch %454
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%454 = OpLabel
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OpSelectionMerge %200 None
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OpBranchConditional %5 %201 %203
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%201 = OpLabel
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%202 = OpLoad %4 %101
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OpBranch %200
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%203 = OpLabel
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%204 = OpCopyObject %4 %5
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OpBranch %200
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%200 = OpLabel
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%522 = OpPhi %4 %202 %201 %204 %203
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OpBranch %462
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%462 = OpLabel
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OpSelectionMerge %300 None
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OpBranchConditional %5 %303 %301
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%301 = OpLabel
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%302 = OpLoad %4 %102
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OpBranch %300
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%303 = OpLabel
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%304 = OpCopyObject %4 %5
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OpBranch %300
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%300 = OpLabel
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%466 = OpPhi %4 %302 %301 %304 %303
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OpBranch %470
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%470 = OpLabel
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%534 = OpSelect %4 %5 %522 %466
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OpReturn
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OpFunctionEnd
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)";
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ASSERT_TRUE(IsEqual(env, after_transformation, context.get()));
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}
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TEST(TransformationFlattenConditionalBranchTest,
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LoadFromBufferBlockDecoratedStruct) {
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std::string shader = R"(
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