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Move the memoization check for SCEVSignExtendExpr and

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SCEVZeroExtendExpr ahead of the most expensive analysis. This
speeds up analysis and helps avoid pathologically bad behavior
on the testcase in PR4534.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75496 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2009-07-13 20:55:53 +00:00
parent 7e25d45cfb
commit 69fbc7f477
1 changed files with 22 additions and 10 deletions
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32
lib/Analysis/ScalarEvolution.cpp
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@ -772,6 +772,15 @@ const SCEV *ScalarEvolution::getZeroExtendExpr(const SCEV *Op,
if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
return getZeroExtendExpr(SZ->getOperand(), Ty);
// Before doing any expensive analysis, check to see if we've already
// computed a SCEV for this Op and Ty.
FoldingSetNodeID ID;
ID.AddInteger(scZeroExtend);
ID.AddPointer(Op);
ID.AddPointer(Ty);
void *IP = 0;
if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
// If the input value is a chrec scev, and we can prove that the value
// did not overflow the old, smaller, value, we can zero extend all of the
// operands (often constants). This allows analysis of something like
@ -836,11 +845,8 @@ const SCEV *ScalarEvolution::getZeroExtendExpr(const SCEV *Op,
}
}
FoldingSetNodeID ID;
ID.AddInteger(scZeroExtend);
ID.AddPointer(Op);
ID.AddPointer(Ty);
void *IP = 0;
// The cast wasn't folded; create an explicit cast node.
// Recompute the insert position, as it may have been invalidated.
if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
SCEV *S = SCEVAllocator.Allocate<SCEVZeroExtendExpr>();
new (S) SCEVZeroExtendExpr(ID, Op, Ty);
@ -868,6 +874,15 @@ const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op,
if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
return getSignExtendExpr(SS->getOperand(), Ty);
// Before doing any expensive analysis, check to see if we've already
// computed a SCEV for this Op and Ty.
FoldingSetNodeID ID;
ID.AddInteger(scSignExtend);
ID.AddPointer(Op);
ID.AddPointer(Ty);
void *IP = 0;
if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
// If the input value is a chrec scev, and we can prove that the value
// did not overflow the old, smaller, value, we can sign extend all of the
// operands (often constants). This allows analysis of something like
@ -916,11 +931,8 @@ const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op,
}
}
FoldingSetNodeID ID;
ID.AddInteger(scSignExtend);
ID.AddPointer(Op);
ID.AddPointer(Ty);
void *IP = 0;
// The cast wasn't folded; create an explicit cast node.
// Recompute the insert position, as it may have been invalidated.
if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
SCEV *S = SCEVAllocator.Allocate<SCEVSignExtendExpr>();
new (S) SCEVSignExtendExpr(ID, Op, Ty);