As you see the compiler has generated code which is using SSE instead of FPU while the /arch:IA32 is set. Any idea why?Code:int c =0; 000000013FD223B5 mov dword ptr [rsp+20h],0 float f=0; 000000013FD223BD xorps xmm0,xmm0 000000013FD223C0 movss dword ptr [rsp+24h],xmm0 int a = c + f; 000000013FD223C6 cvtsi2ss xmm0,dword ptr [rsp+20h] 000000013FD223CC addss xmm0,dword ptr [rsp+24h] 000000013FD223D2 cvttss2si eax,xmm0 000000013FD223D6 mov dword ptr [rsp+28h],eax