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[MemorySSA] Clean up single value phis. 

MemoryPhis with a single value are correct, but can lead to errors when
updating. Clean up single entry Phis newly added when cloning blocks.
Resolves PR46574.
This commit is contained in:
Alina Sbirlea 2020-08-31 16:56:05 -07:00
parent 428b2ffad4
commit 63844c116a
2 changed files with 51 additions and 14 deletions
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32
llvm/lib/Analysis/MemorySSAUpdater.cpp
View File

@ -543,6 +543,20 @@ void MemorySSAUpdater::removeDuplicatePhiEdgesBetween(const BasicBlock *From,
}
}
/// If all arguments of a MemoryPHI are defined by the same incoming
/// argument, return that argument.
static MemoryAccess *onlySingleValue(MemoryPhi *MP) {
MemoryAccess *MA = nullptr;
for (auto &Arg : MP->operands()) {
if (!MA)
MA = cast<MemoryAccess>(Arg);
else if (MA != Arg)
return nullptr;
}
return MA;
}
static MemoryAccess *getNewDefiningAccessForClone(MemoryAccess *MA,
const ValueToValueMapTy &VMap,
PhiToDefMap &MPhiMap,
@ -699,6 +713,10 @@ void MemorySSAUpdater::updateForClonedLoop(const LoopBlocksRPO &LoopBlocks,
NewPhi->addIncoming(IncPhi, IncBB);
}
}
if (onlySingleValue(NewPhi)) {
MPhiMap[Phi] = nullptr;
removeMemoryAccess(NewPhi);
}
};
auto ProcessBlock = [&](BasicBlock *BB) {
@ -1231,20 +1249,6 @@ void MemorySSAUpdater::moveAllAfterMergeBlocks(BasicBlock *From, BasicBlock *To,
MPhi->setIncomingBlock(MPhi->getBasicBlockIndex(From), To);
}
/// If all arguments of a MemoryPHI are defined by the same incoming
/// argument, return that argument.
static MemoryAccess *onlySingleValue(MemoryPhi *MP) {
MemoryAccess *MA = nullptr;
for (auto &Arg : MP->operands()) {
if (!MA)
MA = cast<MemoryAccess>(Arg);
else if (MA != Arg)
return nullptr;
}
return MA;
}
void MemorySSAUpdater::wireOldPredecessorsToNewImmediatePredecessor(
BasicBlock *Old, BasicBlock *New, ArrayRef<BasicBlock *> Preds,
bool IdenticalEdgesWereMerged) {

33
llvm/test/Analysis/MemorySSA/pr46574.ll Normal file
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@ -0,0 +1,33 @@
; RUN: opt -loop-instsimplify -loop-simplifycfg -licm -simple-loop-unswitch -enable-nontrivial-unswitch %s -disable-output
; REQUIRES: asserts
%0 = type { i24, i32, i32, i8 }
@g_1077 = external dso_local local_unnamed_addr global [4 x [3 x [2 x { i8, i8, i8, i8, i8, i8, i8, i8, i32 }]]], align 4
define void @func_22() {
bb:
br label %bb13
bb13: ; preds = %bb38, %bb31, %bb
%i15 = load i32, i32* undef, align 4
%i16 = trunc i32 %i15 to i8
%i18 = load %0*, %0** undef, align 8
%i19 = icmp eq %0* %i18, null
br i1 %i19, label %bb31, label %safe_mod_func_uint8_t_u_u.exit
bb31: ; preds = %bb13
%i25 = load i8, i8* getelementptr inbounds ([4 x [3 x [2 x { i8, i8, i8, i8, i8, i8, i8, i8, i32 }]]], [4 x [3 x [2 x { i8, i8, i8, i8, i8, i8, i8, i8, i32 }]]]* @g_1077, i64 0, i64 2, i64 2, i64 1, i32 6), align 2
%i28 = or i8 %i25, %i16
store i8 %i28, i8* getelementptr inbounds ([4 x [3 x [2 x { i8, i8, i8, i8, i8, i8, i8, i8, i32 }]]], [4 x [3 x [2 x { i8, i8, i8, i8, i8, i8, i8, i8, i32 }]]]* @g_1077, i64 0, i64 2, i64 2, i64 1, i32 6), align 2
%i30 = icmp ne i8 %i28, 0
%i37.not = icmp eq i8 %i16, 0
%or.cond = or i1 %i37.not, %i30
br i1 %or.cond, label %bb13, label %bb38
safe_mod_func_uint8_t_u_u.exit: ; preds = %bb13
br label %bb38
bb38: ; preds = %safe_mod_func_uint8_t_u_u.exit, %bb31
br label %bb13
}