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Add back FoldOpIntoPhi optimizations with fix. Included test cases to help catch these errors and to test the presence of the optimization itself

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170248 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Ilseman 2012-12-14 22:08:26 +00:00
parent f53e7cb9b9
commit 07acee7a09
2 changed files with 43 additions and 0 deletions
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4
lib/Transforms/InstCombine/InstCombineAddSub.cpp
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@ -354,6 +354,10 @@ Instruction *InstCombiner::visitFAdd(BinaryOperator &I) {
if (Value *V = SimplifyFAddInst(LHS, RHS, I.getFastMathFlags(), TD))
return ReplaceInstUsesWith(I, V);
if (isa<Constant>(RHS) && isa<PHINode>(LHS))
if (Instruction *NV = FoldOpIntoPhi(I))
return NV;
// -A + B --> B - A
// -A + -B --> -(A + B)
if (Value *LHSV = dyn_castFNegVal(LHS))

39
test/Transforms/InstCombine/fold-phi.ll Normal file
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@ -0,0 +1,39 @@
; RUN: opt < %s -instcombine -S | FileCheck %s
; CHECK: no_crash
define float @no_crash(float %a) nounwind {
entry:
br label %for.body
for.body:
%sum.057 = phi float [ 0.000000e+00, %entry ], [ %add5, %bb0 ]
%add5 = fadd float %sum.057, %a ; PR14592
br i1 undef, label %bb0, label %end
bb0:
br label %for.body
end:
ret float %add5
}
; CHECK: fold_phi
define float @fold_phi(float %a) nounwind {
entry:
br label %for.body
for.body:
; CHECK: phi float
; CHECK-NEXT: br i1 undef
%sum.057 = phi float [ 0.000000e+00, %entry ], [ %add5, %bb0 ]
%add5 = fadd float %sum.057, 1.0 ;; Should be moved to the latch!
br i1 undef, label %bb0, label %end
; CHECK: bb0:
bb0:
; CHECK: fadd float
br label %for.body
end:
ret float %add5
}