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Make DecomposeGEPExpression check SimplifyInstruction only 

after checking for a GEP, so that it matches what GetUnderlyingObject
does. This fixes an obscure bug turned up by bugpoint in the testcase
for PR9931.

llvm-svn: 131971
This commit is contained in:
Dan Gohman 2011-05-24 18:24:08 +00:00
parent 4ebd019b97
commit 0573b55c2b
2 changed files with 37 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
llvm/lib/Analysis/BasicAliasAnalysis.cpp
View File

@ -281,17 +281,20 @@ DecomposeGEPExpression(const Value *V, int64_t &BaseOffs,
continue;
}
if (const Instruction *I = dyn_cast<Instruction>(V))
// TODO: Get a DominatorTree and use it here.
if (const Value *Simplified =
SimplifyInstruction(const_cast<Instruction *>(I), TD)) {
V = Simplified;
continue;
}
const GEPOperator *GEPOp = dyn_cast<GEPOperator>(Op);
if (GEPOp == 0)
if (GEPOp == 0) {
// If it's not a GEP, hand it off to SimplifyInstruction to see if it
// can come up with something. This matches what GetUnderlyingObject does.
if (const Instruction *I = dyn_cast<Instruction>(V))
// TODO: Get a DominatorTree and use it here.
if (const Value *Simplified =
SimplifyInstruction(const_cast<Instruction *>(I), TD)) {
V = Simplified;
continue;
}
return V;
}
// Don't attempt to analyze GEPs over unsized objects.
if (!cast<PointerType>(GEPOp->getOperand(0)->getType())

25
llvm/test/Analysis/BasicAA/underlying-value.ll Normal file
View File

@ -0,0 +1,25 @@
; RUN: opt -basicaa -licm -S < %s
; PR9931
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
define void @func_20() nounwind {
entry:
br label %for.cond
for.cond: ; preds = %for.cond2, %entry
br i1 undef, label %for.cond2, label %for.end22
for.cond2: ; preds = %for.body5, %for.cond
br i1 false, label %for.body5, label %for.cond
for.body5: ; preds = %for.cond2
%arrayidx = getelementptr inbounds [2 x i64]* undef, i32 0, i64 0
%tmp7 = load i64* %arrayidx, align 8
%arrayidx9 = getelementptr inbounds [2 x i64]* undef, i32 0, i64 undef
%tmp10 = load i64* %arrayidx9, align 8
br label %for.cond2
for.end22: ; preds = %for.cond
ret void
}