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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><div><div><p class=MsoNormal>2) For lag in execution time due to floating point operations, it was clearly observed that gcc used floating point instruction FSQRT, where as clang seemed to use emulated function (?) BL SQRT.<o:p></o:p></p></div><div><p class=MsoNormal>Note that we used the following flags for both clang as well as gcc compilation.<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>-march=armv7-a -mfloat-abi=softfp -mfpu=vfpv3-d16 -mtune=cortex-a8<o:p></o:p></p></div><div><p class=MsoNormal>Infact, i was surprised to see that even when " -march=armv7-a -mfloat-abi=<b>hard</b> -mfpu=vfpv3-d16 -mtune=cortex-a8" <o:p></o:p></p></div><div><p class=MsoNormal>was used, the code generated did not use hardware <b>vsqrt</b> instruction, instead there was a <b>bl sqrt</b> instruction.<o:p></o:p></p></div><div><p class=MsoNormal>Could someone point out why <b>vsqrt </b>was not emited in assembly even though softfp or 'hard' float-abi was specified ?<span style='color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The vsqrt instruction may not be generated when automatically for platforms where math functions may set errno. Try compiling with -fno-math-errno and see if that helps.<o:p></o:p></span></p></div></div></div></div></body></html>