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Simplify trivial cast-of-cast SCEVs.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@69809 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2009-04-22 16:20:48 +00:00
parent aabb04f527
commit 20900cae35
1 changed files with 12 additions and 0 deletions
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12
lib/Analysis/ScalarEvolution.cpp
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@ -654,6 +654,10 @@ SCEVHandle ScalarEvolution::getTruncateExpr(const SCEVHandle &Op, const Type *Ty
return getUnknown(
ConstantExpr::getTrunc(SC->getValue(), Ty));
// trunc(trunc(x)) --> trunc(x)
if (SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op))
return getTruncateExpr(ST->getOperand(), Ty);
// If the input value is a chrec scev made out of constants, truncate
// all of the constants.
if (SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
@ -685,6 +689,10 @@ SCEVHandle ScalarEvolution::getZeroExtendExpr(const SCEVHandle &Op,
return getUnknown(C);
}
// zext(zext(x)) --> zext(x)
if (SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
return getZeroExtendExpr(SZ->getOperand(), Ty);
// FIXME: 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 would allow analysis of something like
@ -706,6 +714,10 @@ SCEVHandle ScalarEvolution::getSignExtendExpr(const SCEVHandle &Op, const Type *
return getUnknown(C);
}
// sext(sext(x)) --> sext(x)
if (SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
return getSignExtendExpr(SS->getOperand(), Ty);
// FIXME: 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 would allow analysis of something like