[llvm] r222338 - AliasSetTracker: UnknownInsts should contribute to the refcount
David Majnemer
david.majnemer at gmail.com
Wed Nov 19 01:41:06 PST 2014
Author: majnemer
Date: Wed Nov 19 03:41:05 2014
New Revision: 222338
URL: http://llvm.org/viewvc/llvm-project?rev=222338&view=rev
Log:
AliasSetTracker: UnknownInsts should contribute to the refcount
AliasSetTracker::addUnknown may create an AliasSet devoid of pointers
just to contain an instruction if no suitable AliasSet already exists.
It will then AliasSet::addUnknownInst and we will be done.
However, it's possible for addUnknown to choose an existing AliasSet to
addUnknownInst.
If this were to occur, we are in a bit of a pickle: removing pointers
from the AliasSet can cause the entire AliasSet to become destroyed,
taking our unknown instructions out with them.
Instead, keep track whether or not our AliasSet has any unknown
instructions.
This fixes PR21582.
Added:
llvm/trunk/test/Transforms/LICM/PR21582.ll
Modified:
llvm/trunk/include/llvm/Analysis/AliasSetTracker.h
llvm/trunk/lib/Analysis/AliasSetTracker.cpp
Modified: llvm/trunk/include/llvm/Analysis/AliasSetTracker.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/AliasSetTracker.h?rev=222338&r1=222337&r2=222338&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/AliasSetTracker.h (original)
+++ llvm/trunk/include/llvm/Analysis/AliasSetTracker.h Wed Nov 19 03:41:05 2014
@@ -254,13 +254,16 @@ private:
const AAMDNodes &AAInfo,
bool KnownMustAlias = false);
void addUnknownInst(Instruction *I, AliasAnalysis &AA);
- void removeUnknownInst(Instruction *I) {
+ void removeUnknownInst(AliasSetTracker &AST, Instruction *I) {
+ bool WasEmpty = UnknownInsts.empty();
for (size_t i = 0, e = UnknownInsts.size(); i != e; ++i)
if (UnknownInsts[i] == I) {
UnknownInsts[i] = UnknownInsts.back();
UnknownInsts.pop_back();
--i; --e; // Revisit the moved entry.
}
+ if (!WasEmpty && UnknownInsts.empty())
+ dropRef(AST);
}
void setVolatile() { Volatile = true; }
Modified: llvm/trunk/lib/Analysis/AliasSetTracker.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/AliasSetTracker.cpp?rev=222338&r1=222337&r2=222338&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/AliasSetTracker.cpp (original)
+++ llvm/trunk/lib/Analysis/AliasSetTracker.cpp Wed Nov 19 03:41:05 2014
@@ -55,12 +55,16 @@ void AliasSet::mergeSetIn(AliasSet &AS,
AliasTy = MayAlias;
}
+ bool ASHadUnknownInsts = false;
if (UnknownInsts.empty()) { // Merge call sites...
- if (!AS.UnknownInsts.empty())
+ if (!AS.UnknownInsts.empty()) {
std::swap(UnknownInsts, AS.UnknownInsts);
+ addRef();
+ }
} else if (!AS.UnknownInsts.empty()) {
UnknownInsts.insert(UnknownInsts.end(), AS.UnknownInsts.begin(), AS.UnknownInsts.end());
AS.UnknownInsts.clear();
+ ASHadUnknownInsts = true;
}
AS.Forward = this; // Forward across AS now...
@@ -76,6 +80,8 @@ void AliasSet::mergeSetIn(AliasSet &AS,
AS.PtrListEnd = &AS.PtrList;
assert(*AS.PtrListEnd == nullptr && "End of list is not null?");
}
+ if (ASHadUnknownInsts)
+ AS.dropRef(AST);
}
void AliasSetTracker::removeAliasSet(AliasSet *AS) {
@@ -123,6 +129,8 @@ void AliasSet::addPointer(AliasSetTracke
}
void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA) {
+ if (UnknownInsts.empty())
+ addRef();
UnknownInsts.push_back(I);
if (!I->mayWriteToMemory()) {
@@ -218,13 +226,14 @@ AliasSet *AliasSetTracker::findAliasSetF
uint64_t Size,
const AAMDNodes &AAInfo) {
AliasSet *FoundSet = nullptr;
- for (iterator I = begin(), E = end(); I != E; ++I) {
- if (I->Forward || !I->aliasesPointer(Ptr, Size, AAInfo, AA)) continue;
+ for (iterator I = begin(), E = end(); I != E;) {
+ iterator Cur = I++;
+ if (Cur->Forward || !Cur->aliasesPointer(Ptr, Size, AAInfo, AA)) continue;
if (!FoundSet) { // If this is the first alias set ptr can go into.
- FoundSet = I; // Remember it.
+ FoundSet = Cur; // Remember it.
} else { // Otherwise, we must merge the sets.
- FoundSet->mergeSetIn(*I, *this); // Merge in contents.
+ FoundSet->mergeSetIn(*Cur, *this); // Merge in contents.
}
}
@@ -251,14 +260,14 @@ bool AliasSetTracker::containsUnknown(In
AliasSet *AliasSetTracker::findAliasSetForUnknownInst(Instruction *Inst) {
AliasSet *FoundSet = nullptr;
- for (iterator I = begin(), E = end(); I != E; ++I) {
- if (I->Forward || !I->aliasesUnknownInst(Inst, AA))
+ for (iterator I = begin(), E = end(); I != E;) {
+ iterator Cur = I++;
+ if (Cur->Forward || !Cur->aliasesUnknownInst(Inst, AA))
continue;
-
if (!FoundSet) // If this is the first alias set ptr can go into.
- FoundSet = I; // Remember it.
- else if (!I->Forward) // Otherwise, we must merge the sets.
- FoundSet->mergeSetIn(*I, *this); // Merge in contents.
+ FoundSet = Cur; // Remember it.
+ else if (!Cur->Forward) // Otherwise, we must merge the sets.
+ FoundSet->mergeSetIn(*Cur, *this); // Merge in contents.
}
return FoundSet;
}
@@ -406,6 +415,8 @@ void AliasSetTracker::add(const AliasSet
/// tracker.
void AliasSetTracker::remove(AliasSet &AS) {
// Drop all call sites.
+ if (!AS.UnknownInsts.empty())
+ AS.dropRef(*this);
AS.UnknownInsts.clear();
// Clear the alias set.
@@ -510,10 +521,10 @@ void AliasSetTracker::deleteValue(Value
if (Instruction *Inst = dyn_cast<Instruction>(PtrVal)) {
if (Inst->mayReadOrWriteMemory()) {
// Scan all the alias sets to see if this call site is contained.
- for (iterator I = begin(), E = end(); I != E; ++I) {
- if (I->Forward) continue;
-
- I->removeUnknownInst(Inst);
+ for (iterator I = begin(), E = end(); I != E;) {
+ iterator Cur = I++;
+ if (!Cur->Forward)
+ Cur->removeUnknownInst(*this, Inst);
}
}
}
Added: llvm/trunk/test/Transforms/LICM/PR21582.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LICM/PR21582.ll?rev=222338&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LICM/PR21582.ll (added)
+++ llvm/trunk/test/Transforms/LICM/PR21582.ll Wed Nov 19 03:41:05 2014
@@ -0,0 +1,40 @@
+; RUN: opt < %s -basicaa -licm -S | FileCheck %s
+ at b = external global i32, align 4
+ at fn3.i = external global i32, align 4
+
+declare i32 @g() nounwind
+
+define i32 @f() {
+entry:
+ br label %for.cond
+
+for.cond: ; preds = %for.end, %entry
+; CHECK-LABEL: for.cond:
+; CHECK: store i32 0, i32* @b
+ store i32 0, i32* @b, align 4
+ br i1 true, label %for.body.preheader, label %for.end
+
+for.body.preheader: ; preds = %for.cond
+ br label %for.body
+
+for.body: ; preds = %for.body, %for.body.preheader
+ %g.15 = phi i32 [ undef, %for.body ], [ 0, %for.body.preheader ]
+ %arrayidx2 = getelementptr inbounds i32* @fn3.i, i64 0
+ %0 = load i32* %arrayidx2, align 4
+ %call = call i32 @g()
+ br i1 false, label %for.body, label %for.end.loopexit
+
+for.end.loopexit: ; preds = %for.body
+ br label %for.end
+
+for.end: ; preds = %for.end.loopexit, %for.cond
+ %whatever = phi i32 [ %call, %for.end.loopexit ], [ undef, %for.cond ]
+ br i1 false, label %for.cond, label %if.then
+
+if.then: ; preds = %for.end
+; CHECK-LABEL: if.then:
+; CHECK: phi i32 [ {{.*}}, %for.end ]
+; CHECK-NOT: store i32 0, i32* @b
+; CHECK: ret i32
+ ret i32 %whatever
+}
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