[LLVMbugs] instcombine fix

Casey Carter ccarter at cs.uiuc.edu
Thu Dec 5 13:28:32 PST 2002

I noticed that one of the reassociate regression tests -- 
2002-07-09-DominanceProblem -- was failing.  instcombine was transforming

%A.neg = sub int 0, %A
%.neg = sub int 0, 1
%X = add int %.neg, 1
%Y.neg.ra = add int %A, %X
%r = add int %A.neg, %Y.neg.ra
ret int %r


%Y.neg.ra = add int %A, 0
%r = add int %A.neg, %Y.neg.ra
ret int %r

without reexamining %Y.neg.ra to see that it is clearly replacable by 
%A.  The problem is that instcombine's runOnFunction does not add uses 
of a constant-folded instruction into its worklist for examination.

Casey Carter
Casey at Carter.net
ccarter at uiuc.edu
AIM: cartec69

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