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[MemorySSA] Make sure PerformedPhiTrans is updated for each visited def.

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1ce82015f6d0 added a fix to restrict phi optimizations after phi
translations. But the current use of performedPhiTranslation only
checked whether phi translation happened for the first iterator and
missed cases where phi translations happens at subsequent
iterators/upwards defs.

This patch changes upward_defs_iteartor to take a pointer to a bool, so
we can easily ensure the final value includes all visited defs, while
still being able to conveniently use it with make_range & co.
This commit is contained in:
Florian Hahn 2020-09-14 15:51:17 +01:00
parent b5a8746b47
commit 200286e570
3 changed files with 16 additions and 15 deletions
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20
include/llvm/Analysis/MemorySSA.h
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@ -1181,9 +1181,11 @@ class upward_defs_iterator
using BaseT = upward_defs_iterator::iterator_facade_base;
public:
upward_defs_iterator(const MemoryAccessPair &Info, DominatorTree *DT)
upward_defs_iterator(const MemoryAccessPair &Info, DominatorTree *DT,
bool *PerformedPhiTranslation = nullptr)
: DefIterator(Info.first), Location(Info.second),
OriginalAccess(Info.first), DT(DT) {
OriginalAccess(Info.first), DT(DT),
PerformedPhiTranslation(PerformedPhiTranslation) {
CurrentPair.first = nullptr;
WalkingPhi = Info.first && isa<MemoryPhi>(Info.first);
@ -1214,8 +1216,6 @@ public:
BasicBlock *getPhiArgBlock() const { return DefIterator.getPhiArgBlock(); }
bool performedPhiTranslation() const { return PerformedPhiTranslation; }
private:
void fillInCurrentPair() {
CurrentPair.first = *DefIterator;
@ -1228,7 +1228,8 @@ private:
false)) {
if (Translator.getAddr() != Location.Ptr) {
CurrentPair.second = Location.getWithNewPtr(Translator.getAddr());
PerformedPhiTranslation = true;
if (PerformedPhiTranslation)
*PerformedPhiTranslation = true;
return;
}
} else {
@ -1245,12 +1246,13 @@ private:
MemoryAccess *OriginalAccess = nullptr;
DominatorTree *DT = nullptr;
bool WalkingPhi = false;
bool PerformedPhiTranslation = false;
bool *PerformedPhiTranslation = nullptr;
};
inline upward_defs_iterator upward_defs_begin(const MemoryAccessPair &Pair,
DominatorTree &DT) {
return upward_defs_iterator(Pair, &DT);
inline upward_defs_iterator
upward_defs_begin(const MemoryAccessPair &Pair, DominatorTree &DT,
bool *PerformedPhiTranslation = nullptr) {
return upward_defs_iterator(Pair, &DT, PerformedPhiTranslation);
}
inline upward_defs_iterator upward_defs_end() { return upward_defs_iterator(); }

4
lib/Analysis/MemorySSA.cpp
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@ -603,13 +603,13 @@ template <class AliasAnalysisType> class ClobberWalker {
void addSearches(MemoryPhi *Phi, SmallVectorImpl<ListIndex> &PausedSearches,
ListIndex PriorNode) {
auto UpwardDefsBegin = upward_defs_begin({Phi, Paths[PriorNode].Loc}, DT);
auto UpwardDefsBegin = upward_defs_begin({Phi, Paths[PriorNode].Loc}, DT,
&PerformedPhiTranslation);
auto UpwardDefs = make_range(UpwardDefsBegin, upward_defs_end());
for (const MemoryAccessPair &P : UpwardDefs) {
PausedSearches.push_back(Paths.size());
Paths.emplace_back(P.second, P.first, PriorNode);
}
PerformedPhiTranslation |= UpwardDefsBegin.performedPhiTranslation();
}
/// Represents a search that terminated after finding a clobber. This clobber

7
test/Analysis/MemorySSA/phi-translation.ll
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@ -384,10 +384,9 @@ define void @dont_merge_noalias_complex_2(i32 %arg, i32 %arg1) {
; CHECK-NEXT: call void @init([32 x i32]* %tmp)
; CHECK-LABEL: loop.1.header:
; CHECK-NEXT: ; 4 = MemoryPhi({entry,1},{loop.1.latch,3})
; NOLIMIT: ; MemoryUse(1) MayAlias
; LIMIT: ; MemoryUse(4) MayAlias
; CHECK-NEXT: %l.1 = load i32, i32* %p.1, align 4
; CHECK-NEXT: ; 4 = MemoryPhi({entry,1},{loop.1.latch,3})
; CHECK: ; MemoryUse(4) MayAlias
; CHECK-NEXT: %l.1 = load i32, i32* %p.1, align 4
; CHECK-LABEL: loop.1.latch:
; CHECK-NEXT: ; 3 = MemoryPhi({loop.1.header,4},{storebb,2})