http://llvm.org/bugs/show_bug.cgi?id=21468
Bug ID: 21468
Summary: GVN should be able to sink instruction into the latch
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: Scalar Optimizations
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
The following used to be optimized by FoldOpIntoPhi before r221187 but this
stopped being the case after it was determine that permitting FoldOpIntoPhi to
insert instructions that the PHI may reach will lead to infinite loops.
Perhaps GVN should catch this instead.
; 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
}
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