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List:       cfe-commits
Subject:    Re: [PATCH] use __builtin_convertvector for _mm_cvtepi32_ps to enable constant propagation
From:       Matthias Kretz <kretz () kde ! org>
Date:       2013-10-01 7:36:55
Message-ID: 0bd7bff09ceef8846990429eaf692741 () llvm-reviews ! chandlerc ! com
[Download RAW message or body]


  Testcase:


    __m128 cvt0() { return _mm_cvtepi32_ps(_mm_set1_epi32(2)); }
    __m128 cvt0(__m128i x) { return _mm_cvtepi32_ps(x); }

  compiles to IR:


    define <4 x float> @_Z4cvt0v() #0 {
    entry:
      ret <4 x float> <float 2.000000e+00, float 2.000000e+00, float 2.000000e+00, \
float 2.000000e+00>  }

    define <4 x float> @_Z4cvt0Dv2_x(<2 x i64> %x) #0 {
    entry:
      %0 = bitcast <2 x i64> %x to <4 x i32>
      %conv.i = sitofp <4 x i32> %0 to <4 x float>
      ret <4 x float> %conv.i
    }

  and x86:


    0000000000000000 <cvt0()>:
       0: ·       c5 f8 28 05 00 00 00 00  · vmovaps 0x0(%rip),%xmm0        # 8 \
<cvt0()+0x8> ·    4: R_X86_64_PC32 ·         .LCPI0_0-0x4  8: ·       c3              \
·    retq

    0000000000000010 <cvt0(long long __vector(2))>:
      10: ·       c5 f8 5b c0           ·    vcvtdq2ps %xmm0,%xmm0
      14: ·       c3                    ·    retq

http://llvm-reviews.chandlerc.com/D1792
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