[LLVMbugs] [Bug 19356] New: builtin cabs(z) resp. hypot(z) squared should be optimized

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=19356

            Bug ID: 19356
           Summary: builtin cabs(z) resp. hypot(z) squared should be
                    optimized
           Product: clang
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: LLVM Codegen
          Assignee: unassignedclangbugs at nondot.org
          Reporter: mrmocool at gmx.de
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

#include <complex>
float abs2(std::complex<float> c)
{
    return abs(c) * abs(c);
}

$ clang++ -mllvm --x86-asm-syntax=intel -std=c++11 -O3 -g -ffast-math -S
test.cpp

    .type    bar(std::complex<float>), at function
bar(std::complex<float>):                    # @bar(std::complex<float>)
.Lfunc_begin0:
# BB#0:                                 # %entry
    .loc    3 584 0 prologue_end    # /usr/include/c++/4.8/complex:584:0
 582:/usr/include/c++/4.8/complex **** #if _GLIBCXX_USE_C99_COMPLEX
 583:/usr/include/c++/4.8/complex ****   inline float
 584:/usr/include/c++/4.8/complex ****   __complex_abs(__complex__ float __z) {
return __builtin_cabsf(__z); }

    push    rax
.Ltmp0:
    .cfi_def_cfa_offset 16
    call    cabsf
.Ltmp1:
    .loc    1 4 18                 # testcomplex.cpp:4:18
    mulss    xmm0, xmm0
    pop    rax
    ret

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