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Make SCEVCallbackVH::allUsesReplacedWith update the old SCEVUnknown

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object, as it may still be referenced by SCEVs not cleaned up by the
use list traversal.

Also, in ScalarEvolution::forgetValue, only check for a SCEVUnknown
object for the original value, not for any value in the use list,
because other SCEVUnknown values aren't necessary obsolete at that
point.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109570 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-07-28 01:09:07 +00:00
parent 59846aced2
commit 81f9121cda
1 changed files with 39 additions and 22 deletions
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61
lib/Analysis/ScalarEvolution.cpp
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@ -3664,6 +3664,26 @@ void ScalarEvolution::forgetLoop(const Loop *L) {
/// changed a value in a way that may effect its value, or which may
/// disconnect it from a def-use chain linking it to a loop.
void ScalarEvolution::forgetValue(Value *V) {
// If there's a SCEVUnknown tying this value into the SCEV
// space, remove it from the folding set map. The SCEVUnknown
// object and any other SCEV objects which reference it
// (transitively) remain allocated, effectively leaked until
// the underlying BumpPtrAllocator is freed.
//
// This permits SCEV pointers to be used as keys in maps
// such as the ValuesAtScopes map.
FoldingSetNodeID ID;
ID.AddInteger(scUnknown);
ID.AddPointer(V);
void *IP;
if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) {
UniqueSCEVs.RemoveNode(S);
// This isn't necessary, but we might as well remove the
// value from the ValuesAtScopes map too.
ValuesAtScopes.erase(S);
}
Instruction *I = dyn_cast<Instruction>(V);
if (!I) return;
@ -3685,26 +3705,6 @@ void ScalarEvolution::forgetValue(Value *V) {
ConstantEvolutionLoopExitValue.erase(PN);
}
// If there's a SCEVUnknown tying this value into the SCEV
// space, remove it from the folding set map. The SCEVUnknown
// object and any other SCEV objects which reference it
// (transitively) remain allocated, effectively leaked until
// the underlying BumpPtrAllocator is freed.
//
// This permits SCEV pointers to be used as keys in maps
// such as the ValuesAtScopes map.
FoldingSetNodeID ID;
ID.AddInteger(scUnknown);
ID.AddPointer(I);
void *IP;
if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) {
UniqueSCEVs.RemoveNode(S);
// This isn't necessary, but we might as well remove the
// value from the ValuesAtScopes map too.
ValuesAtScopes.erase(S);
}
PushDefUseChildren(I, Worklist);
}
}
@ -5690,15 +5690,32 @@ void ScalarEvolution::SCEVCallbackVH::deleted() {
// this now dangles!
}
void ScalarEvolution::SCEVCallbackVH::allUsesReplacedWith(Value *) {
void ScalarEvolution::SCEVCallbackVH::allUsesReplacedWith(Value *V) {
assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!");
Value *Old = getValPtr();
// If there's a SCEVUnknown tying this value into the SCEV
// space, replace the SCEVUnknown's value with the new value
// for the benefit of any SCEVs still referencing it, and
// and remove it from the folding set map so that new scevs
// don't reference it.
FoldingSetNodeID ID;
ID.AddInteger(scUnknown);
ID.AddPointer(Old);
void *IP;
if (SCEVUnknown *S = cast_or_null<SCEVUnknown>(
SE->UniqueSCEVs.FindNodeOrInsertPos(ID, IP))) {
S->V = V;
SE->UniqueSCEVs.RemoveNode(S);
SE->ValuesAtScopes.erase(S);
}
// Forget all the expressions associated with users of the old value,
// so that future queries will recompute the expressions using the new
// value.
SmallVector<User *, 16> Worklist;
SmallPtrSet<User *, 8> Visited;
Value *Old = getValPtr();
for (Value::use_iterator UI = Old->use_begin(), UE = Old->use_end();
UI != UE; ++UI)
Worklist.push_back(*UI);