[llvm-bugs] [Bug 39205] New: [X86][AVX512] Strange uitofp v2i64 to v2f32 legalization

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=39205

            Bug ID: 39205
           Summary: [X86][AVX512] Strange uitofp v2i64 to v2f32
                    legalization
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Backend: X86
          Assignee: unassignedbugs at nondot.org
          Reporter: llvm-dev at redking.me.uk
                CC: craig.topper at gmail.com, llvm-bugs at lists.llvm.org,
                    zvi.rackover at intel.com

https://gcc.godbolt.org/z/-HRm6i

Why 3 vcvtusi2ssq entries?

llc -matrr=+avx512f

define <4 x float> @uitofp_2i64_2f32(<2 x i64> %a) {
  %cvt = uitofp <2 x i64> %a to <2 x float>
  %ext = shufflevector <2 x float> %cvt, <2 x float> undef, <4 x i32> <i32 0,
i32 1, i32 undef, i32 undef>
  ret <4 x float> %ext
}

define <4 x float> @uitofp_2i64_4f32(<2 x i64> %a) {
  %ext = shufflevector <2 x i64> %a, <2 x i64> undef, <4 x i32> <i32 0, i32 1,
i32 undef, i32 undef>
  %cvt = uitofp <4 x i64> %ext to <4 x float>
  ret <4 x float> %cvt
}

uitofp_2i64_2f32: # @uitofp_2i64_2f32
  vpextrq $1, %xmm0, %rax
  vcvtusi2ssq %rax, %xmm1, %xmm1
  vmovq %xmm0, %rax
  vcvtusi2ssq %rax, %xmm2, %xmm0
  vinsertps $16, %xmm1, %xmm0, %xmm0 # xmm0 = xmm0[0],xmm1[0],xmm0[2,3]
  vcvtusi2ssq %rax, %xmm2, %xmm1
  vshufps $4, %xmm1, %xmm0, %xmm0 # xmm0 = xmm0[0,1],xmm1[0,0]
  retq

uitofp_2i64_4f32: # @uitofp_2i64_4f32
  vpextrq $1, %xmm0, %rax
  vcvtusi2ssq %rax, %xmm1, %xmm1
  vmovq %xmm0, %rax
  vcvtusi2ssq %rax, %xmm2, %xmm0
  vinsertps $16, %xmm1, %xmm0, %xmm0 # xmm0 = xmm0[0],xmm1[0],xmm0[2,3]
  vcvtusi2ssq %rax, %xmm2, %xmm1
  vshufps $4, %xmm1, %xmm0, %xmm0 # xmm0 = xmm0[0,1],xmm1[0,0]
  retq

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