[PATCH] D65148: [SimplifyCFG] Bump phi-node-folding-threshold from 2 to 3
Nikita Popov via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Aug 15 12:33:37 PDT 2019
nikic added a comment.
@lebedev.ri CVP can already determine that the condition is always true:
define i1 @test(i8 %a, i8 %b) {
%conv1 = sext i8 %a to i32
%conv3 = sext i8 %b to i32
%mul = mul nsw i32 %conv3, %conv1
%shr = ashr i32 %mul, 7
br label %split
split:
%icmp = icmp sgt i32 %shr, -128
ret i1 %icmp
}
This becomes `ret i1 true` under `-correlated-propagation`. Unfortunately CVP has some limitations on icmp simplification that makes it only work in cross-BB scenarios. Relaxing those is not entirely straightforward (iirc it had some negative effects due to LVI query order changes).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D65148/new/
https://reviews.llvm.org/D65148
More information about the llvm-commits
mailing list