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[GVN] When merging blocks update LoopInfo if it's available

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If LoopInfo is available during GVN, BasicAA will use it.  However
MergeBlockIntoPredecessor does not update LI as it merges blocks.

This didn't use to cause problems because LI was freed before
GVN/BasicAA.  Now with OptimizationRemarkEmitter, the lifetime of LI is
extended so LI needs to be kept up-to-date during GVN.

Differential Revision: https://reviews.llvm.org/D27288

llvm-svn: 288307
This commit is contained in:
Adam Nemet 2016-12-01 03:56:43 +00:00
parent a46f4c6583
commit 2a29152193
3 changed files with 62 additions and 7 deletions
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3
include/llvm/Transforms/Scalar/GVN.h
View File

@ -22,6 +22,7 @@
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/IntrinsicInst.h"
@ -134,7 +135,7 @@ private:
bool runImpl(Function &F, AssumptionCache &RunAC, DominatorTree &RunDT,
const TargetLibraryInfo &RunTLI, AAResults &RunAA,
MemoryDependenceResults *RunMD);
MemoryDependenceResults *RunMD, LoopInfo *LI);
/// Push a new Value to the LeaderTable onto the list for its value number.
void addToLeaderTable(uint32_t N, Value *V, const BasicBlock *BB) {

16
lib/Transforms/Scalar/GVN.cpp
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@ -586,7 +586,8 @@ PreservedAnalyses GVN::run(Function &F, FunctionAnalysisManager &AM) {
auto &TLI = AM.getResult<TargetLibraryAnalysis>(F);
auto &AA = AM.getResult<AAManager>(F);
auto &MemDep = AM.getResult<MemoryDependenceAnalysis>(F);
bool Changed = runImpl(F, AC, DT, TLI, AA, &MemDep);
auto *LI = AM.getCachedResult<LoopAnalysis>(F);
bool Changed = runImpl(F, AC, DT, TLI, AA, &MemDep, LI);
if (!Changed)
return PreservedAnalyses::all();
PreservedAnalyses PA;
@ -2179,7 +2180,7 @@ bool GVN::processInstruction(Instruction *I) {
/// runOnFunction - This is the main transformation entry point for a function.
bool GVN::runImpl(Function &F, AssumptionCache &RunAC, DominatorTree &RunDT,
const TargetLibraryInfo &RunTLI, AAResults &RunAA,
MemoryDependenceResults *RunMD) {
MemoryDependenceResults *RunMD, LoopInfo *LI) {
AC = &RunAC;
DT = &RunDT;
VN.setDomTree(DT);
@ -2196,9 +2197,9 @@ bool GVN::runImpl(Function &F, AssumptionCache &RunAC, DominatorTree &RunDT,
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ) {
BasicBlock *BB = &*FI++;
bool removedBlock =
MergeBlockIntoPredecessor(BB, DT, /* LoopInfo */ nullptr, MD);
if (removedBlock) ++NumGVNBlocks;
bool removedBlock = MergeBlockIntoPredecessor(BB, DT, LI, MD);
if (removedBlock)
++NumGVNBlocks;
Changed |= removedBlock;
}
@ -2693,13 +2694,16 @@ public:
if (skipFunction(F))
return false;
auto *LIWP = getAnalysisIfAvailable<LoopInfoWrapperPass>();
return Impl.runImpl(
F, getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F),
getAnalysis<DominatorTreeWrapperPass>().getDomTree(),
getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(),
getAnalysis<AAResultsWrapperPass>().getAAResults(),
NoLoads ? nullptr
: &getAnalysis<MemoryDependenceWrapperPass>().getMemDep());
: &getAnalysis<MemoryDependenceWrapperPass>().getMemDep(),
LIWP ? &LIWP->getLoopInfo() : nullptr);
}
void getAnalysisUsage(AnalysisUsage &AU) const override {

50
test/Transforms/GVN/stale-loop-info.ll Normal file
View File

@ -0,0 +1,50 @@
; RUN: opt -loops -gvn -S < %s | FileCheck %s
; This used to fail with ASAN enabled and if for some reason LoopInfo remained
; available during GVN. In this case BasicAA will use LI but
; MergeBlockIntoPredecessor in GVN failed to update LI.
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
%struct.wibble.1028 = type { i32, i32, %struct.barney.881 }
%struct.barney.881 = type { %struct.zot.882 }
%struct.zot.882 = type { [64 x i8] }
; Function Attrs: argmemonly
declare void @snork.1(i8*) local_unnamed_addr #0
define hidden zeroext i1 @eggs(%struct.wibble.1028* %arg, i1 %arg2) unnamed_addr align 2 {
bb:
br i1 %arg2, label %bb14, label %bb3
bb3: ; preds = %bb
%tmp = getelementptr inbounds %struct.wibble.1028, %struct.wibble.1028* %arg, i64 0, i32 2, i32 0, i32 0, i64 0
%tmp5 = bitcast i8* %tmp to %struct.wibble.1028**
br label %bb6
bb6: ; preds = %bb12, %bb3
br label %bb7
bb7: ; preds = %bb6
br i1 undef, label %bb11, label %bb8
bb8: ; preds = %bb7
%tmp9 = load %struct.wibble.1028*, %struct.wibble.1028** %tmp5, align 8
; CHECK: %tmp9 = load %struct.wibble.1028*, %struct.wibble.1028** %tmp5, align 8
%tmp10 = bitcast %struct.wibble.1028* %tmp9 to i8*
br label %bb12
bb11: ; preds = %bb7
br label %bb12
bb12: ; preds = %bb11, %bb8
%tmp13 = phi i8* [ %tmp, %bb11 ], [ %tmp10, %bb8 ]
call void @snork.1(i8* %tmp13) #1
br label %bb6
bb14: ; preds = %bb
ret i1 false
}
attributes #0 = { argmemonly }
attributes #1 = { nounwind }