[llvm-bugs] [Bug 29125] New: [AArch64] shufflevector with constants uses 4 ext instructions

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=29125

            Bug ID: 29125
           Summary: [AArch64] shufflevector with constants uses 4 ext
                    instructions
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: Backend: AArch64
          Assignee: unassignedbugs at nondot.org
          Reporter: spatel+llvm at rotateright.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

I don't know AArch, but this doesn't look good:

define <4 x float> @goo(<4 x float> %x) {
  %shuf = shufflevector <4 x float> %x, <4 x float> <float undef, float 1.0,
float 2.0, float undef>, <4 x i32><i32 0, i32 5, i32 6, i32 3>
  ret <4 x float> %shuf
}

$ ./llc -o - min.ll -mtriple=aarch64
    adrp    x8, .LCPI1_0
    ldr    q1, [x8, :lo12:.LCPI1_0]
    ext    v1.16b, v0.16b, v1.16b, #12
    ext    v0.16b, v1.16b, v0.16b, #4
    ext    v1.16b, v1.16b, v1.16b, #8
    ext    v0.16b, v0.16b, v1.16b, #12
    ret

--------------------------------------------------------------------------

Should this be 'bsl'?

Or 2 inserts?
    fmov    s1, #1.00000000
    ins    v0.s[1], v1.s[0]
    fmov    s1, #2.00000000
    ins    v0.s[2], v1.s[0]
    ret

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20160824/705443d5/attachment.html>