[llvm-bugs] [Bug 41125] New: Difference in undef vector simplification

via llvm-bugs llvm-bugs at lists.llvm.org
Mon Mar 18 08:11:19 PDT 2019


https://bugs.llvm.org/show_bug.cgi?id=41125

            Bug ID: 41125
           Summary: Difference in undef vector simplification
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: lebedev.ri at gmail.com
                CC: llvm-bugs at lists.llvm.org

https://reviews.llvm.org/D59363#inline-526625
https://reviews.llvm.org/D59363#inline-526625

define <4 x i32> @test_urem_div_undef(<4 x i32> %X) nounwind readnone {
  %urem = urem <4 x i32> %X, <i32 5, i32 5, i32 undef, i32 5>
  %cmp = icmp eq <4 x i32> %urem, <i32 0, i32 0, i32 0, i32 0>
  %ret = zext <4 x i1> %cmp to <4 x i32>
  ret <4 x i32> %ret
}

-instsimplify says it's zeroinitializer
but codegen will say it's splat of `1`.

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