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[CodeExtractor] Update function's assumption cache after extracting blocks from it

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Summary: Assumption cache's self-updating mechanism does not correctly handle the case when blocks are extracted from the function by the CodeExtractor. As a result function's assumption cache may have stale references to the llvm.assume calls that were moved to the outlined function. This patch fixes this problem by removing extracted llvm.assume calls from the function’s assumption cache.

Reviewers: hfinkel, vsk, fhahn, davidxl, sanjoy

Reviewed By: hfinkel, vsk

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D57215

llvm-svn: 353500
This commit is contained in:
Sergey Dmitriev 2019-02-08 06:55:18 +00:00
parent b0ccbffc74
commit c02969bade
8 changed files with 144 additions and 33 deletions
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8
include/llvm/Analysis/AssumptionCache.h
View File

@ -103,6 +103,10 @@ public:
/// not already be in the cache.
void registerAssumption(CallInst *CI);
/// Remove an \@llvm.assume intrinsic from this function's cache if it has
/// been added to the cache earlier.
void unregisterAssumption(CallInst *CI);
/// Update the cache of values being affected by this assumption (i.e.
/// the values about which this assumption provides information).
void updateAffectedValues(CallInst *CI);
@ -208,6 +212,10 @@ public:
/// existing cache will be returned.
AssumptionCache &getAssumptionCache(Function &F);
/// Return the cached assumptions for a function if it has already been
/// scanned. Otherwise return nullptr.
AssumptionCache *lookupAssumptionCache(Function &F);
AssumptionCacheTracker();
~AssumptionCacheTracker() override;

4
include/llvm/Transforms/Utils/CodeExtractor.h
View File

@ -26,6 +26,7 @@ class BasicBlock;
class BlockFrequency;
class BlockFrequencyInfo;
class BranchProbabilityInfo;
class AssumptionCache;
class CallInst;
class DominatorTree;
class Function;
@ -56,6 +57,7 @@ class Value;
const bool AggregateArgs;
BlockFrequencyInfo *BFI;
BranchProbabilityInfo *BPI;
AssumptionCache *AC;
// If true, varargs functions can be extracted.
bool AllowVarArgs;
@ -84,6 +86,7 @@ class Value;
CodeExtractor(ArrayRef<BasicBlock *> BBs, DominatorTree *DT = nullptr,
bool AggregateArgs = false, BlockFrequencyInfo *BFI = nullptr,
BranchProbabilityInfo *BPI = nullptr,
AssumptionCache *AC = nullptr,
bool AllowVarArgs = false, bool AllowAlloca = false,
std::string Suffix = "");
@ -94,6 +97,7 @@ class Value;
CodeExtractor(DominatorTree &DT, Loop &L, bool AggregateArgs = false,
BlockFrequencyInfo *BFI = nullptr,
BranchProbabilityInfo *BPI = nullptr,
AssumptionCache *AC = nullptr,
std::string Suffix = "");
/// Perform the extraction, returning the new function.

28
lib/Analysis/AssumptionCache.cpp
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@ -53,11 +53,11 @@ AssumptionCache::getOrInsertAffectedValues(Value *V) {
return AVIP.first->second;
}
void AssumptionCache::updateAffectedValues(CallInst *CI) {
static void findAffectedValues(CallInst *CI,
SmallVectorImpl<Value *> &Affected) {
// Note: This code must be kept in-sync with the code in
// computeKnownBitsFromAssume in ValueTracking.
SmallVector<Value *, 16> Affected;
auto AddAffected = [&Affected](Value *V) {
if (isa<Argument>(V)) {
Affected.push_back(V);
@ -108,6 +108,11 @@ void AssumptionCache::updateAffectedValues(CallInst *CI) {
AddAffectedFromEq(B);
}
}
}
void AssumptionCache::updateAffectedValues(CallInst *CI) {
SmallVector<Value *, 16> Affected;
findAffectedValues(CI, Affected);
for (auto &AV : Affected) {
auto &AVV = getOrInsertAffectedValues(AV);
@ -116,6 +121,18 @@ void AssumptionCache::updateAffectedValues(CallInst *CI) {
}
}
void AssumptionCache::unregisterAssumption(CallInst *CI) {
SmallVector<Value *, 16> Affected;
findAffectedValues(CI, Affected);
for (auto &AV : Affected) {
auto AVI = AffectedValues.find_as(AV);
if (AVI != AffectedValues.end())
AffectedValues.erase(AVI);
}
remove_if(AssumeHandles, [CI](WeakTrackingVH &VH) { return CI == VH; });
}
void AssumptionCache::AffectedValueCallbackVH::deleted() {
auto AVI = AC->AffectedValues.find(getValPtr());
if (AVI != AC->AffectedValues.end())
@ -240,6 +257,13 @@ AssumptionCache &AssumptionCacheTracker::getAssumptionCache(Function &F) {
return *IP.first->second;
}
AssumptionCache *AssumptionCacheTracker::lookupAssumptionCache(Function &F) {
auto I = AssumptionCaches.find_as(&F);
if (I != AssumptionCaches.end())
return I->second.get();
return nullptr;
}
void AssumptionCacheTracker::verifyAnalysis() const {
// FIXME: In the long term the verifier should not be controllable with a
// flag. We should either fix all passes to correctly update the assumption

33
lib/Transforms/IPO/HotColdSplitting.cpp
View File

@ -173,8 +173,9 @@ public:
HotColdSplitting(ProfileSummaryInfo *ProfSI,
function_ref<BlockFrequencyInfo *(Function &)> GBFI,
function_ref<TargetTransformInfo &(Function &)> GTTI,
std::function<OptimizationRemarkEmitter &(Function &)> *GORE)
: PSI(ProfSI), GetBFI(GBFI), GetTTI(GTTI), GetORE(GORE) {}
std::function<OptimizationRemarkEmitter &(Function &)> *GORE,
function_ref<AssumptionCache *(Function &)> LAC)
: PSI(ProfSI), GetBFI(GBFI), GetTTI(GTTI), GetORE(GORE), LookupAC(LAC) {}
bool run(Module &M);
private:
@ -183,11 +184,13 @@ private:
bool outlineColdRegions(Function &F, bool HasProfileSummary);
Function *extractColdRegion(const BlockSequence &Region, DominatorTree &DT,
BlockFrequencyInfo *BFI, TargetTransformInfo &TTI,
OptimizationRemarkEmitter &ORE, unsigned Count);
OptimizationRemarkEmitter &ORE,
AssumptionCache *AC, unsigned Count);
ProfileSummaryInfo *PSI;
function_ref<BlockFrequencyInfo *(Function &)> GetBFI;
function_ref<TargetTransformInfo &(Function &)> GetTTI;
std::function<OptimizationRemarkEmitter &(Function &)> *GetORE;
function_ref<AssumptionCache *(Function &)> LookupAC;
};
class HotColdSplittingLegacyPass : public ModulePass {
@ -198,10 +201,10 @@ public:
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<AssumptionCacheTracker>();
AU.addRequired<BlockFrequencyInfoWrapperPass>();
AU.addRequired<ProfileSummaryInfoWrapperPass>();
AU.addRequired<TargetTransformInfoWrapperPass>();
AU.addUsedIfAvailable<AssumptionCacheTracker>();
}
bool runOnModule(Module &M) override;
@ -316,12 +319,13 @@ Function *HotColdSplitting::extractColdRegion(const BlockSequence &Region,
BlockFrequencyInfo *BFI,
TargetTransformInfo &TTI,
OptimizationRemarkEmitter &ORE,
AssumptionCache *AC,
unsigned Count) {
assert(!Region.empty());
// TODO: Pass BFI and BPI to update profile information.
CodeExtractor CE(Region, &DT, /* AggregateArgs */ false, /* BFI */ nullptr,
/* BPI */ nullptr, /* AllowVarArgs */ false,
/* BPI */ nullptr, AC, /* AllowVarArgs */ false,
/* AllowAlloca */ false,
/* Suffix */ "cold." + std::to_string(Count));
@ -577,6 +581,7 @@ bool HotColdSplitting::outlineColdRegions(Function &F, bool HasProfileSummary) {
TargetTransformInfo &TTI = GetTTI(F);
OptimizationRemarkEmitter &ORE = (*GetORE)(F);
AssumptionCache *AC = LookupAC(F);
// Find all cold regions.
for (BasicBlock *BB : RPOT) {
@ -638,8 +643,8 @@ bool HotColdSplitting::outlineColdRegions(Function &F, bool HasProfileSummary) {
BB->dump();
});
Function *Outlined =
extractColdRegion(SubRegion, *DT, BFI, TTI, ORE, OutlinedFunctionID);
Function *Outlined = extractColdRegion(SubRegion, *DT, BFI, TTI, ORE, AC,
OutlinedFunctionID);
if (Outlined) {
++OutlinedFunctionID;
Changed = true;
@ -698,17 +703,21 @@ bool HotColdSplittingLegacyPass::runOnModule(Module &M) {
ORE.reset(new OptimizationRemarkEmitter(&F));
return *ORE.get();
};
auto LookupAC = [this](Function &F) -> AssumptionCache * {
if (auto *ACT = getAnalysisIfAvailable<AssumptionCacheTracker>())
return ACT->lookupAssumptionCache(F);
return nullptr;
};
return HotColdSplitting(PSI, GBFI, GTTI, &GetORE).run(M);
return HotColdSplitting(PSI, GBFI, GTTI, &GetORE, LookupAC).run(M);
}
PreservedAnalyses
HotColdSplittingPass::run(Module &M, ModuleAnalysisManager &AM) {
auto &FAM = AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
std::function<AssumptionCache &(Function &)> GetAssumptionCache =
[&FAM](Function &F) -> AssumptionCache & {
return FAM.getResult<AssumptionAnalysis>(F);
auto LookupAC = [&FAM](Function &F) -> AssumptionCache * {
return FAM.getCachedResult<AssumptionAnalysis>(F);
};
auto GBFI = [&FAM](Function &F) {
@ -729,7 +738,7 @@ HotColdSplittingPass::run(Module &M, ModuleAnalysisManager &AM) {
ProfileSummaryInfo *PSI = &AM.getResult<ProfileSummaryAnalysis>(M);
if (HotColdSplitting(PSI, GBFI, GTTI, &GetORE).run(M))
if (HotColdSplitting(PSI, GBFI, GTTI, &GetORE, LookupAC).run(M))
return PreservedAnalyses::none();
return PreservedAnalyses::all();
}

7
lib/Transforms/IPO/LoopExtractor.cpp
View File

@ -14,6 +14,7 @@
//===----------------------------------------------------------------------===//
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Instructions.h"
@ -50,6 +51,7 @@ namespace {
AU.addRequiredID(LoopSimplifyID);
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<LoopInfoWrapperPass>();
AU.addUsedIfAvailable<AssumptionCacheTracker>();
}
};
}
@ -138,7 +140,10 @@ bool LoopExtractor::runOnLoop(Loop *L, LPPassManager &LPM) {
if (ShouldExtractLoop) {
if (NumLoops == 0) return Changed;
--NumLoops;
CodeExtractor Extractor(DT, *L);
AssumptionCache *AC = nullptr;
if (auto *ACT = getAnalysisIfAvailable<AssumptionCacheTracker>())
AC = ACT->lookupAssumptionCache(*L->getHeader()->getParent());
CodeExtractor Extractor(DT, *L, false, nullptr, nullptr, AC);
if (Extractor.extractCodeRegion() != nullptr) {
Changed = true;
// After extraction, the loop is replaced by a function call, so

46
lib/Transforms/IPO/PartialInlining.cpp
View File

@ -199,10 +199,12 @@ struct PartialInlinerImpl {
PartialInlinerImpl(
std::function<AssumptionCache &(Function &)> *GetAC,
function_ref<AssumptionCache *(Function &)> LookupAC,
std::function<TargetTransformInfo &(Function &)> *GTTI,
Optional<function_ref<BlockFrequencyInfo &(Function &)>> GBFI,
ProfileSummaryInfo *ProfSI)
: GetAssumptionCache(GetAC), GetTTI(GTTI), GetBFI(GBFI), PSI(ProfSI) {}
: GetAssumptionCache(GetAC), LookupAssumptionCache(LookupAC),
GetTTI(GTTI), GetBFI(GBFI), PSI(ProfSI) {}
bool run(Module &M);
// Main part of the transformation that calls helper functions to find
@ -222,9 +224,11 @@ struct PartialInlinerImpl {
// Two constructors, one for single region outlining, the other for
// multi-region outlining.
FunctionCloner(Function *F, FunctionOutliningInfo *OI,
OptimizationRemarkEmitter &ORE);
OptimizationRemarkEmitter &ORE,
function_ref<AssumptionCache *(Function &)> LookupAC);
FunctionCloner(Function *F, FunctionOutliningMultiRegionInfo *OMRI,
OptimizationRemarkEmitter &ORE);
OptimizationRemarkEmitter &ORE,
function_ref<AssumptionCache *(Function &)> LookupAC);
~FunctionCloner();
// Prepare for function outlining: making sure there is only
@ -260,11 +264,13 @@ struct PartialInlinerImpl {
std::unique_ptr<FunctionOutliningMultiRegionInfo> ClonedOMRI = nullptr;
std::unique_ptr<BlockFrequencyInfo> ClonedFuncBFI = nullptr;
OptimizationRemarkEmitter &ORE;
function_ref<AssumptionCache *(Function &)> LookupAC;
};
private:
int NumPartialInlining = 0;
std::function<AssumptionCache &(Function &)> *GetAssumptionCache;
function_ref<AssumptionCache *(Function &)> LookupAssumptionCache;
std::function<TargetTransformInfo &(Function &)> *GetTTI;
Optional<function_ref<BlockFrequencyInfo &(Function &)>> GetBFI;
ProfileSummaryInfo *PSI;
@ -365,12 +371,17 @@ struct PartialInlinerLegacyPass : public ModulePass {
return ACT->getAssumptionCache(F);
};
auto LookupAssumptionCache = [ACT](Function &F) -> AssumptionCache * {
return ACT->lookupAssumptionCache(F);
};
std::function<TargetTransformInfo &(Function &)> GetTTI =
[&TTIWP](Function &F) -> TargetTransformInfo & {
return TTIWP->getTTI(F);
};
return PartialInlinerImpl(&GetAssumptionCache, &GetTTI, NoneType::None, PSI)
return PartialInlinerImpl(&GetAssumptionCache, LookupAssumptionCache,
&GetTTI, NoneType::None, PSI)
.run(M);
}
};
@ -948,8 +959,9 @@ void PartialInlinerImpl::computeCallsiteToProfCountMap(
}
PartialInlinerImpl::FunctionCloner::FunctionCloner(
Function *F, FunctionOutliningInfo *OI, OptimizationRemarkEmitter &ORE)
: OrigFunc(F), ORE(ORE) {
Function *F, FunctionOutliningInfo *OI, OptimizationRemarkEmitter &ORE,
function_ref<AssumptionCache *(Function &)> LookupAC)
: OrigFunc(F), ORE(ORE), LookupAC(LookupAC) {
ClonedOI = llvm::make_unique<FunctionOutliningInfo>();
// Clone the function, so that we can hack away on it.
@ -972,8 +984,9 @@ PartialInlinerImpl::FunctionCloner::FunctionCloner(
PartialInlinerImpl::FunctionCloner::FunctionCloner(
Function *F, FunctionOutliningMultiRegionInfo *OI,
OptimizationRemarkEmitter &ORE)
: OrigFunc(F), ORE(ORE) {
OptimizationRemarkEmitter &ORE,
function_ref<AssumptionCache *(Function &)> LookupAC)
: OrigFunc(F), ORE(ORE), LookupAC(LookupAC) {
ClonedOMRI = llvm::make_unique<FunctionOutliningMultiRegionInfo>();
// Clone the function, so that we can hack away on it.
@ -1111,7 +1124,9 @@ bool PartialInlinerImpl::FunctionCloner::doMultiRegionFunctionOutlining() {
int CurrentOutlinedRegionCost = ComputeRegionCost(RegionInfo.Region);
CodeExtractor CE(RegionInfo.Region, &DT, /*AggregateArgs*/ false,
ClonedFuncBFI.get(), &BPI, /* AllowVarargs */ false);
ClonedFuncBFI.get(), &BPI,
LookupAC(*RegionInfo.EntryBlock->getParent()),
/* AllowVarargs */ false);
CE.findInputsOutputs(Inputs, Outputs, Sinks);
@ -1193,7 +1208,7 @@ PartialInlinerImpl::FunctionCloner::doSingleRegionFunctionOutlining() {
// Extract the body of the if.
Function *OutlinedFunc =
CodeExtractor(ToExtract, &DT, /*AggregateArgs*/ false,
ClonedFuncBFI.get(), &BPI,
ClonedFuncBFI.get(), &BPI, LookupAC(*ClonedFunc),
/* AllowVarargs */ true)
.extractCodeRegion();
@ -1257,7 +1272,7 @@ std::pair<bool, Function *> PartialInlinerImpl::unswitchFunction(Function *F) {
std::unique_ptr<FunctionOutliningMultiRegionInfo> OMRI =
computeOutliningColdRegionsInfo(F, ORE);
if (OMRI) {
FunctionCloner Cloner(F, OMRI.get(), ORE);
FunctionCloner Cloner(F, OMRI.get(), ORE, LookupAssumptionCache);
#ifndef NDEBUG
if (TracePartialInlining) {
@ -1290,7 +1305,7 @@ std::pair<bool, Function *> PartialInlinerImpl::unswitchFunction(Function *F) {
if (!OI)
return {false, nullptr};
FunctionCloner Cloner(F, OI.get(), ORE);
FunctionCloner Cloner(F, OI.get(), ORE, LookupAssumptionCache);
Cloner.NormalizeReturnBlock();
Function *OutlinedFunction = Cloner.doSingleRegionFunctionOutlining();
@ -1484,6 +1499,10 @@ PreservedAnalyses PartialInlinerPass::run(Module &M,
return FAM.getResult<AssumptionAnalysis>(F);
};
auto LookupAssumptionCache = [&FAM](Function &F) -> AssumptionCache * {
return FAM.getCachedResult<AssumptionAnalysis>(F);
};
std::function<BlockFrequencyInfo &(Function &)> GetBFI =
[&FAM](Function &F) -> BlockFrequencyInfo & {
return FAM.getResult<BlockFrequencyAnalysis>(F);
@ -1496,7 +1515,8 @@ PreservedAnalyses PartialInlinerPass::run(Module &M,
ProfileSummaryInfo *PSI = &AM.getResult<ProfileSummaryAnalysis>(M);
if (PartialInlinerImpl(&GetAssumptionCache, &GetTTI, {GetBFI}, PSI)
if (PartialInlinerImpl(&GetAssumptionCache, LookupAssumptionCache, &GetTTI,
{GetBFI}, PSI)
.run(M))
return PreservedAnalyses::none();
return PreservedAnalyses::all();

22
lib/Transforms/Utils/CodeExtractor.cpp
View File

@ -20,6 +20,7 @@
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/BlockFrequencyInfo.h"
#include "llvm/Analysis/BlockFrequencyInfoImpl.h"
#include "llvm/Analysis/BranchProbabilityInfo.h"
@ -43,6 +44,7 @@
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/User.h"
#include "llvm/IR/Value.h"
@ -66,6 +68,7 @@
#include <vector>
using namespace llvm;
using namespace llvm::PatternMatch;
using ProfileCount = Function::ProfileCount;
#define DEBUG_TYPE "code-extractor"
@ -235,18 +238,20 @@ buildExtractionBlockSet(ArrayRef<BasicBlock *> BBs, DominatorTree *DT,
CodeExtractor::CodeExtractor(ArrayRef<BasicBlock *> BBs, DominatorTree *DT,
bool AggregateArgs, BlockFrequencyInfo *BFI,
BranchProbabilityInfo *BPI, bool AllowVarArgs,
bool AllowAlloca, std::string Suffix)
BranchProbabilityInfo *BPI, AssumptionCache *AC,
bool AllowVarArgs, bool AllowAlloca,
std::string Suffix)
: DT(DT), AggregateArgs(AggregateArgs || AggregateArgsOpt), BFI(BFI),
BPI(BPI), AllowVarArgs(AllowVarArgs),
BPI(BPI), AC(AC), AllowVarArgs(AllowVarArgs),
Blocks(buildExtractionBlockSet(BBs, DT, AllowVarArgs, AllowAlloca)),
Suffix(Suffix) {}
CodeExtractor::CodeExtractor(DominatorTree &DT, Loop &L, bool AggregateArgs,
BlockFrequencyInfo *BFI,
BranchProbabilityInfo *BPI, std::string Suffix)
BranchProbabilityInfo *BPI, AssumptionCache *AC,
std::string Suffix)
: DT(&DT), AggregateArgs(AggregateArgs || AggregateArgsOpt), BFI(BFI),
BPI(BPI), AllowVarArgs(false),
BPI(BPI), AC(AC), AllowVarArgs(false),
Blocks(buildExtractionBlockSet(L.getBlocks(), &DT,
/* AllowVarArgs */ false,
/* AllowAlloca */ false)),
@ -1216,6 +1221,13 @@ void CodeExtractor::moveCodeToFunction(Function *newFunction) {
// Insert this basic block into the new function
newBlocks.push_back(Block);
// Remove @llvm.assume calls that were moved to the new function from the
// old function's assumption cache.
if (AC)
for (auto &I : *Block)
if (match(&I, m_Intrinsic<Intrinsic::assume>()))
AC->unregisterAssumption(cast<CallInst>(&I));
}
}

29
test/Transforms/CodeExtractor/extract-assume.ll Normal file
View File

@ -0,0 +1,29 @@
; RUN: opt -passes="function(slp-vectorizer),module(hotcoldsplit),function(slp-vectorizer,print<assumptions>)" -disable-output %s 2>&1 | FileCheck %s
;
; Make sure this compiles. Check that function assumption cache is refreshed
; after extracting blocks with assume calls from the function.
; CHECK: Cached assumptions for function: fun
; CHECK-NEXT: Cached assumptions for function: fun.cold
; CHECK-NEXT: %cmp = icmp uge i32 %x, 64
declare void @fun2(i32) #0
define void @fun(i32 %x) {
entry:
br i1 undef, label %if.then, label %if.else
if.then:
ret void
if.else:
%cmp = icmp uge i32 %x, 64
call void @llvm.assume(i1 %cmp)
call void @fun2(i32 %x)
unreachable
}
declare void @llvm.assume(i1) #1
attributes #0 = { alwaysinline }
attributes #1 = { nounwind }