[PATCH] D43762: [IPSCCP] Use constant range information for comparisons of parameters.

Matthew Simpson via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Thu Mar 22 08:27:57 PDT 2018


mssimpso added inline comments.


================
Comment at: test/Transforms/SCCP/ip-constant-ranges.ll:5
 ; CHECK-LABEL: f1
-; CHECK-NOT: icmp
-; CHECK: %a.1 = select i1 false, i32 1, i32 2
-; CHECK: %b.1 = select i1 true, i32 1, i32 2
-; CHECK: %a.2 = select i1 false, i32 1, i32 2
-; CHECK: %b.2 = select i1 true, i32 1, i32 2
+; CHECK: ret i32 undef
 define internal i32 @f1(i32 %a, i32 %b) {
----------------
mssimpso wrote:
> Hi Florian,
> 
> I'm not understanding why we end up with `undef` here. Can you help me out?
Ah, it's because the function becomes dead after the simplification in `@caller1`. Right?


https://reviews.llvm.org/D43762





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