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Update MemorySSA in LoopInstSimplify.

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Summary:
Add MemorySSA as a depency to LoopInstInstSimplify and preserve it.
Disabled by default until all passes preserve MemorySSA.

Reviewers: chandlerc

Subscribers: sanjoy, jlebar, Prazek, george.burgess.iv, llvm-commits

Differential Revision: https://reviews.llvm.org/D50906

llvm-svn: 340444
This commit is contained in:
Alina Sbirlea 2018-08-22 20:05:21 +00:00
parent eff472e2cf
commit 0cb48ba57d
2 changed files with 39 additions and 6 deletions
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44
lib/Transforms/Scalar/LoopInstSimplify.cpp
View File

@ -22,8 +22,9 @@
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/LoopIterator.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/MemorySSA.h"
#include "llvm/Analysis/MemorySSAUpdater.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/DataLayout.h"
@ -36,6 +37,7 @@
#include "llvm/Pass.h"
#include "llvm/Support/Casting.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/LoopUtils.h"
#include <algorithm>
#include <utility>
@ -47,8 +49,8 @@ using namespace llvm;
STATISTIC(NumSimplified, "Number of redundant instructions simplified");
static bool simplifyLoopInst(Loop &L, DominatorTree &DT, LoopInfo &LI,
AssumptionCache &AC,
const TargetLibraryInfo &TLI) {
AssumptionCache &AC, const TargetLibraryInfo &TLI,
MemorySSAUpdater *MSSAU) {
const DataLayout &DL = L.getHeader()->getModule()->getDataLayout();
SimplifyQuery SQ(DL, &TLI, &DT, &AC);
@ -75,9 +77,12 @@ static bool simplifyLoopInst(Loop &L, DominatorTree &DT, LoopInfo &LI,
// iterate.
LoopBlocksRPO RPOT(&L);
RPOT.perform(&LI);
MemorySSA *MSSA = MSSAU ? MSSAU->getMemorySSA() : nullptr;
bool Changed = false;
for (;;) {
if (MSSAU && VerifyMemorySSA)
MSSA->verifyMemorySSA();
for (BasicBlock *BB : RPOT) {
for (Instruction &I : *BB) {
if (auto *PI = dyn_cast<PHINode>(&I))
@ -129,6 +134,12 @@ static bool simplifyLoopInst(Loop &L, DominatorTree &DT, LoopInfo &LI,
ToSimplify->insert(UserI);
}
if (MSSAU)
if (Instruction *SimpleI = dyn_cast_or_null<Instruction>(V))
if (MemoryAccess *MA = MSSA->getMemoryAccess(&I))
if (MemoryAccess *ReplacementMA = MSSA->getMemoryAccess(SimpleI))
MA->replaceAllUsesWith(ReplacementMA);
assert(I.use_empty() && "Should always have replaced all uses!");
if (isInstructionTriviallyDead(&I, &TLI))
DeadInsts.push_back(&I);
@ -141,9 +152,12 @@ static bool simplifyLoopInst(Loop &L, DominatorTree &DT, LoopInfo &LI,
// iteration over all instructions in all the loop blocks.
if (!DeadInsts.empty()) {
Changed = true;
RecursivelyDeleteTriviallyDeadInstructions(DeadInsts, &TLI);
RecursivelyDeleteTriviallyDeadInstructions(DeadInsts, &TLI, MSSAU);
}
if (MSSAU && VerifyMemorySSA)
MSSA->verifyMemorySSA();
// If we never found a PHI that needs to be simplified in the next
// iteration, we're done.
if (Next->empty())
@ -180,8 +194,15 @@ public:
*L->getHeader()->getParent());
const TargetLibraryInfo &TLI =
getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
MemorySSA *MSSA = nullptr;
Optional<MemorySSAUpdater> MSSAU;
if (EnableMSSALoopDependency) {
MSSA = &getAnalysis<MemorySSAWrapperPass>().getMSSA();
MSSAU = MemorySSAUpdater(MSSA);
}
return simplifyLoopInst(*L, DT, LI, AC, TLI);
return simplifyLoopInst(*L, DT, LI, AC, TLI,
MSSAU.hasValue() ? MSSAU.getPointer() : nullptr);
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
@ -189,6 +210,10 @@ public:
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<TargetLibraryInfoWrapperPass>();
AU.setPreservesCFG();
if (EnableMSSALoopDependency) {
AU.addRequired<MemorySSAWrapperPass>();
AU.addPreserved<MemorySSAWrapperPass>();
}
getLoopAnalysisUsage(AU);
}
};
@ -198,7 +223,13 @@ public:
PreservedAnalyses LoopInstSimplifyPass::run(Loop &L, LoopAnalysisManager &AM,
LoopStandardAnalysisResults &AR,
LPMUpdater &) {
if (!simplifyLoopInst(L, AR.DT, AR.LI, AR.AC, AR.TLI))
Optional<MemorySSAUpdater> MSSAU;
if (AR.MSSA) {
MSSAU = MemorySSAUpdater(AR.MSSA);
AR.MSSA->verifyMemorySSA();
}
if (!simplifyLoopInst(L, AR.DT, AR.LI, AR.AC, AR.TLI,
MSSAU.hasValue() ? MSSAU.getPointer() : nullptr))
return PreservedAnalyses::all();
auto PA = getLoopPassPreservedAnalyses();
@ -212,6 +243,7 @@ INITIALIZE_PASS_BEGIN(LoopInstSimplifyLegacyPass, "loop-instsimplify",
"Simplify instructions in loops", false, false)
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
INITIALIZE_PASS_DEPENDENCY(LoopPass)
INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_END(LoopInstSimplifyLegacyPass, "loop-instsimplify",
"Simplify instructions in loops", false, false)

1
test/Transforms/LoopInstSimplify/basic.ll
View File

@ -1,5 +1,6 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S %s -passes=loop-instsimplify | FileCheck %s
; RUN: opt -S %s -passes=loop-instsimplify -enable-mssa-loop-dependency=true -verify-memoryssa | FileCheck %s
; Test very basic folding and propagation occurs within a loop body. This should
; collapse to the loop iteration structure and the LCSSA PHI node.