[llvm-bugs] [Bug 43750] New: [AVX512] cannot select: extract f64 from splatted "movemask"

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=43750

            Bug ID: 43750
           Summary: [AVX512] cannot select: extract f64 from splatted
                    "movemask"
           Product: libraries
           Version: 9.0
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: normal
          Priority: P
         Component: Backend: X86
          Assignee: unassignedbugs at nondot.org
          Reporter: andrew at scheidecker.net
                CC: craig.topper at gmail.com, llvm-bugs at lists.llvm.org,
                    llvm-dev at redking.me.uk, spatel+llvm at rotateright.com

I can reproduce this error in my local build of LLVM 9 and "LLC (trunk)" on
Compiler Explorer, but LLC 8.0.0 on Compiler Explorer does not reproduce the
error.

It also only repros with '-mcpu=skylake-avx512', or some other CPU with AVX-512
support. If I use '-mcpu=skylake' or '-mattr=-avx512f', the error does not
occur.

Repro module: 

  define double @0(<16 x i8>) {
  entry:
    %1 = icmp slt <16 x i8> %0, zeroinitializer
    %2 = bitcast <16 x i1> %1 to i16
    %.splatinsert = insertelement <8 x i16> undef, i16 %2, i32 0
    %.splat = shufflevector <8 x i16> %.splatinsert, <8 x i16> undef, <8 x i32>
<i32 undef, i32 undef, i32 undef, i32 undef, i32 0, i32 0, i32 0, i32 0>
    %3 = bitcast <8 x i16> %.splat to <2 x double>
    %4 = extractelement <2 x double> %3, i64 1
    ret double %4
  }

Run:

  llc -mcpu=skylake-avx512 repro.ll

Output:

  LLVM ERROR: Cannot select: 0x5608e0d8ba08: f64 = bitcast 0x5608e0d8bc78
    0x5608e0d8bc78: v64i1 = concat_vectors 0x5608e0d8c2f8, 0x5608e0d8c2f8
      0x5608e0d8c2f8: v32i1 = concat_vectors 0x5608e0d8bad8, 0x5608e0d8bad8
        0x5608e0d8bad8: v16i1 = setcc 0x5608e0d8b9a0, 0x5608e0d8b8d0, setgt:ch
          0x5608e0d8b9a0: v16i8 = BUILD_VECTOR Constant:i8<0>, Constant:i8<0>,
Constant:i8<0>, Constant:i8<0>, Constant:i8<0>, Constant:i8<0>, Constant:i8<0>,
Constant:i8<0>, Constant:i8<0>, Constant:i8<0>, Constant:i8<0>,
Constant:i8<0>,Constant:i8<0>, Constant:i8<0>, Constant:i8<0>, Constant:i8<0
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
          0x5608e0d8b8d0: v16i8 = bitcast 0x5608e0d8b868
            0x5608e0d8b868: v2i64,ch = CopyFromReg 0x5608e0cf7998,
Register:v2i64 %0
              0x5608e0d8b800: v2i64 = Register %0
        0x5608e0d8bad8: v16i1 = setcc 0x5608e0d8b9a0, 0x5608e0d8b8d0, setgt:ch
          0x5608e0d8b9a0: v16i8 = BUILD_VECTOR Constant:i8<0>, Constant:i8<0>,
Constant:i8<0>, Constant:i8<0>, Constant:i8<0>, Constant:i8<0>, Constant:i8<0>,
Constant:i8<0>, Constant:i8<0>, Constant:i8<0>, Constant:i8<0>,
Constant:i8<0>,Constant:i8<0>, Constant:i8<0>, Constant:i8<0>, Constant:i8<0
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
          0x5608e0d8b8d0: v16i8 = bitcast 0x5608e0d8b868
            0x5608e0d8b868: v2i64,ch = CopyFromReg 0x5608e0cf7998,
Register:v2i64 %0
              0x5608e0d8b800: v2i64 = Register %0
      0x5608e0d8c2f8: v32i1 = concat_vectors 0x5608e0d8bad8, 0x5608e0d8bad8
        0x5608e0d8bad8: v16i1 = setcc 0x5608e0d8b9a0, 0x5608e0d8b8d0, setgt:ch
          0x5608e0d8b9a0: v16i8 = BUILD_VECTOR Constant:i8<0>, Constant:i8<0>,
Constant:i8<0>, Constant:i8<0>, Constant:i8<0>, Constant:i8<0>, Constant:i8<0>,
Constant:i8<0>, Constant:i8<0>, Constant:i8<0>, Constant:i8<0>,
Constant:i8<0>,Constant:i8<0>, Constant:i8<0>, Constant:i8<0>, Constant:i8<0
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
          0x5608e0d8b8d0: v16i8 = bitcast 0x5608e0d8b868
            0x5608e0d8b868: v2i64,ch = CopyFromReg 0x5608e0cf7998,
Register:v2i64 %0
              0x5608e0d8b800: v2i64 = Register %0
        0x5608e0d8bad8: v16i1 = setcc 0x5608e0d8b9a0, 0x5608e0d8b8d0, setgt:ch
          0x5608e0d8b9a0: v16i8 = BUILD_VECTOR Constant:i8<0>, Constant:i8<0>,
Constant:i8<0>, Constant:i8<0>, Constant:i8<0>, Constant:i8<0>, Constant:i8<0>,
Constant:i8<0>, Constant:i8<0>, Constant:i8<0>, Constant:i8<0>,
Constant:i8<0>,Constant:i8<0>, Constant:i8<0>, Constant:i8<0>, Constant:i8<0
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
            0x5608e0d8b938: i8 = Constant<0>
          0x5608e0d8b8d0: v16i8 = bitcast 0x5608e0d8b868
            0x5608e0d8b868: v2i64,ch = CopyFromReg 0x5608e0cf7998,
Register:v2i64 %0
              0x5608e0d8b800: v2i64 = Register %0

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