nlopes added a comment.
This patch regressed the following test of Transforms/InstCombine/abs-1.ll:
(need to drop NSW in this case).
define i8 @nabs_canonical_3(i8 %x) {
%0:
%cmp = icmp slt i8 %x, 0
%neg = sub nsw i8 0, %x
%abs = select i1 %cmp, i8 %x, i8 %neg
ret i8 %abs
}
=>
define i8 @nabs_canonical_3(i8 %x) {
%0:
%1 = abs i8 %x, 1
%abs = sub nsw i8 0, %1
ret i8 %abs
}
Transformation doesn't verify!
ERROR: Target is more poisonous than source
Example:
i8 %x = #x80 (128, -128)
Source:
i1 %cmp = #x1 (1)
i8 %neg = poison
i8 %abs = #x80 (128, -128)
Target:
i8 %1 = poison
i8 %abs = poison
Source value: #x80 (128, -128)
Target value: poison
(same bug occurs with @nabs_nabs_x01 in Transforms/InstCombine/abs_abs.ll)
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D87188/new/
https://reviews.llvm.org/D87188
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
