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[SPIR-V] Fix flakiness during switch generation. #95001

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Merged
merged 1 commit into from
Jun 11, 2024
Merged

[SPIR-V] Fix flakiness during switch generation. #95001

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25 changes: 14 additions & 11 deletions llvm/lib/Target/SPIRV/SPIRVMergeRegionExitTargets.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,8 @@
#include "SPIRVSubtarget.h"
#include "SPIRVTargetMachine.h"
#include "SPIRVUtils.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/CodeGen/IntrinsicLowering.h"
#include "llvm/IR/CFG.h"
Expand Down Expand Up @@ -71,7 +73,7 @@ class SPIRVMergeRegionExitTargets : public FunctionPass {
/// terminator will take.
llvm::Value *createExitVariable(
BasicBlock *BB,
const std::unordered_map<BasicBlock *, ConstantInt *> &TargetToValue) {
const DenseMap<BasicBlock *, ConstantInt *> &TargetToValue) {
auto *T = BB->getTerminator();
if (isa<ReturnInst>(T))
return nullptr;
Expand Down Expand Up @@ -103,7 +105,7 @@ class SPIRVMergeRegionExitTargets : public FunctionPass {

/// Replaces |BB|'s branch targets present in |ToReplace| with |NewTarget|.
void replaceBranchTargets(BasicBlock *BB,
const std::unordered_set<BasicBlock *> ToReplace,
const SmallPtrSet<BasicBlock *, 4> &ToReplace,
BasicBlock *NewTarget) {
auto *T = BB->getTerminator();
if (isa<ReturnInst>(T))
Expand Down Expand Up @@ -133,7 +135,7 @@ class SPIRVMergeRegionExitTargets : public FunctionPass {
bool runOnConvergenceRegionNoRecurse(LoopInfo &LI,
const SPIRV::ConvergenceRegion *CR) {
// Gather all the exit targets for this region.
std::unordered_set<BasicBlock *> ExitTargets;
SmallPtrSet<BasicBlock *, 4> ExitTargets;
for (BasicBlock *Exit : CR->Exits) {
for (BasicBlock *Target : gatherSuccessors(Exit)) {
if (CR->Blocks.count(Target) == 0)
Expand Down Expand Up @@ -164,9 +166,10 @@ class SPIRVMergeRegionExitTargets : public FunctionPass {

// Creating one constant per distinct exit target. This will be route to the
// correct target.
std::unordered_map<BasicBlock *, ConstantInt *> TargetToValue;
DenseMap<BasicBlock *, ConstantInt *> TargetToValue;
for (BasicBlock *Target : SortedExitTargets)
TargetToValue.emplace(Target, Builder.getInt32(TargetToValue.size()));
TargetToValue.insert(
std::make_pair(Target, Builder.getInt32(TargetToValue.size())));

// Creating one variable per exit node, set to the constant matching the
// targeted external block.
Expand All @@ -184,12 +187,12 @@ class SPIRVMergeRegionExitTargets : public FunctionPass {
}

// Creating the switch to jump to the correct exit target.
std::vector<std::pair<BasicBlock *, ConstantInt *>> CasesList(
TargetToValue.begin(), TargetToValue.end());
llvm::SwitchInst *Sw =
Builder.CreateSwitch(node, CasesList[0].first, CasesList.size() - 1);
for (size_t i = 1; i < CasesList.size(); i++)
Sw->addCase(CasesList[i].second, CasesList[i].first);
llvm::SwitchInst *Sw = Builder.CreateSwitch(node, SortedExitTargets[0],
SortedExitTargets.size() - 1);
for (size_t i = 1; i < SortedExitTargets.size(); i++) {
BasicBlock *BB = SortedExitTargets[i];
Sw->addCase(TargetToValue[BB], BB);
}

// Fix exit branches to redirect to the new exit.
for (auto Exit : CR->Exits)
Expand Down
2 changes: 1 addition & 1 deletion llvm/test/CodeGen/SPIRV/structurizer/merge-exit-break.ll
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Expand Up @@ -66,7 +66,7 @@ while.end:

; CHECK: %[[#new_end]] = OpLabel
; CHECK: %[[#route:]] = OpPhi %[[#int_ty]] %[[#int_1]] %[[#while_cond]] %[[#int_0]] %[[#while_body]]
; CHECK: OpSwitch %[[#route]] %[[#while_end_loopexit]] 0 %[[#if_then]]
; CHECK: OpSwitch %[[#route]] %[[#if_then]] 1 %[[#while_end_loopexit]]
}

declare token @llvm.experimental.convergence.entry() #2
Expand Down
2 changes: 1 addition & 1 deletion llvm/test/CodeGen/SPIRV/structurizer/merge-exit-convergence-in-break.ll
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Expand Up @@ -75,7 +75,7 @@ while.end:

; CHECK: %[[#new_end]] = OpLabel
; CHECK: %[[#route:]] = OpPhi %[[#int_ty]] %[[#int_0]] %[[#while_cond]] %[[#int_1]] %[[#tail]]
; CHECK: OpSwitch %[[#route]] %[[#while_end]] 0 %[[#while_end_loopexit]]
; CHECK: OpSwitch %[[#route]] %[[#while_end_loopexit]] 1 %[[#while_end]]
}

declare token @llvm.experimental.convergence.entry() #2
Expand Down
2 changes: 1 addition & 1 deletion llvm/test/CodeGen/SPIRV/structurizer/merge-exit-multiple-break.ll
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Expand Up @@ -85,7 +85,7 @@ while.end:

; CHECK: %[[#new_end]] = OpLabel
; CHECK: %[[#route:]] = OpPhi %[[#int_ty]] %[[#int_2]] %[[#while_cond]] %[[#int_0]] %[[#while_body]] %[[#int_1]] %[[#if_end]]
; CHECK: OpSwitch %[[#route]] %[[#while_end_loopexit]] 1 %[[#if_then2]] 0 %[[#if_then]]
; CHECK: OpSwitch %[[#route]] %[[#if_then]] 1 %[[#if_then2]] 2 %[[#while_end_loopexit]]
}

declare token @llvm.experimental.convergence.entry() #2
Expand Down
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