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Add a missing SCEV simplification sext(zext x) --> zext x.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123832 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2011-01-19 15:56:12 +00:00
parent ec91d52a77
commit 73f565e754
2 changed files with 12 additions and 0 deletions
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4
lib/Analysis/ScalarEvolution.cpp
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@ -994,6 +994,10 @@ const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op,
if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
return getSignExtendExpr(SS->getOperand(), Ty);
// sext(zext(x)) --> zext(x)
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;

8
test/Analysis/ScalarEvolution/fold.ll Normal file
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@ -0,0 +1,8 @@
; RUN: opt -analyze -scalar-evolution %s -S | FileCheck %s
define i16 @test(i8 %x) {
%A = zext i8 %x to i12
%B = sext i12 %A to i16
; CHECK: zext i8 %x to i16
ret i16 %B
}