InstCombine incorrectly folds select of vector #49176
Description
| Bugzilla Link | 49832 |
| Resolution | FIXED |
| Resolved on | May 29, 2021 08:41 |
| Version | trunk |
| OS | All |
| Blocks | #48246 #48661 |
| CC | @RKSimon,@nikic,@smeenai,@rotateright,@tstellar |
| Fixed by commit(s) | c0b0da4 c590a98 78e5cf6 e2a0f51 c89d500 4a12f51 266c82f 8e2ff38 |
Extended Description
$ cat src.ll define void @​src(<2 x i32> %input) { %cond = icmp eq <2 x i32> %input, zeroinitializer %.14 = extractelement <2 x i32> %input, i32 1 %.15 = insertelement <2 x i32> poison, i32 %.14, i32 0 %.16 = extractelement <2 x i32> %input, i32 0 %.17 = insertelement <2 x i32> %.15, i32 %.16, i32 1 %.18 = select <2 x i1> %cond, <2 x i32> %.17, <2 x i32> %input %x = extractelement <2 x i32> %.18, i32 0 %y = extractelement <2 x i32> %.18, i32 1 call void @​f(i32 %x, i32 %y) ret void } declare void @​f(i32, i32) $ opt -instcombine -S -o - src.ll define void @​src(<2 x i32> %input) { %x = extractelement <2 x i32> %input, i32 0 %y = extractelement <2 x i32> %input, i32 1 call void @​f(i32 %x, i32 %y) ret void } declare void @​f(i32, i32) This is incorrect: https://alive2.llvm.org/ce/z/8X-4kR
If input is <0, 2>, (%x, %y) is (2, 2) in src, but it becomes (0, 2) in tgt.