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Test case and comment for PR9633.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130294 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2011-04-27 05:42:17 +00:00
parent 3f5c832909
commit 104f4adeac
2 changed files with 36 additions and 2 deletions
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5
lib/Analysis/ScalarEvolution.cpp
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@ -4705,8 +4705,9 @@ const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) {
getAddRecExpr(NewOps, AddRec->getLoop(),
AddRec->getNoWrapFlags(SCEV::FlagNW));
AddRec = dyn_cast<SCEVAddRecExpr>(FoldedRec);
// In cases with "undef" values, a loop's own recurrence may
// fold into a constant. Go ahead and return the optimistic value.
// The addrec may be folded to a nonrecurrence, for example, if the
// induction variable is multiplied by zero after constant folding. Go
// ahead and return the folded value.
if (!AddRec)
return FoldedRec;
break;

33
test/Analysis/ScalarEvolution/2011-04-26-FoldAddRec.ll Normal file
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@ -0,0 +1,33 @@
; RUN: opt < %s -analyze -iv-users
; PR9633: Tests that SCEV handles the mul.i2 recurrence being folded to
; constant zero.
define signext i8 @func_14(i8 signext %p_18) nounwind readnone ssp {
entry:
br label %for.inc
for.inc:
%p_17.addr.012 = phi i32 [ 0, %entry ], [ %add, %for.inc ]
%add = add nsw i32 %p_17.addr.012, 1
br i1 false, label %for.inc, label %for.cond
for.cond:
%tobool.i = icmp ult i32 %add, 8192
%shl.i = select i1 %tobool.i, i32 13, i32 0
%shl.left.i = shl i32 %add, %shl.i
%conv.i4 = trunc i32 %shl.left.i to i8
br i1 undef, label %for.inc9, label %if.then
for.inc9:
%p_18.addr.011 = phi i8 [ %add12, %for.inc9 ], [ %p_18, %for.cond ]
%add12 = add i8 %p_18.addr.011, 1
%mul.i2 = mul i8 %add12, %conv.i4
%mul.i2.lobit = lshr i8 %mul.i2, 7
%lor.ext.shr.i = select i1 undef, i8 %mul.i2.lobit, i8 %mul.i2
%tobool = icmp eq i8 %lor.ext.shr.i, 0
br i1 %tobool, label %for.inc9, label %if.then
if.then:
ret i8 0
}