assembly - FPU IA-32 SIGFPE, Arithmetic exception

Question

I have a problem with this code below. It is GAS asm syntax on IA-32 architecture. It generates arithmetic exception, after fsqrt instruction. SetDouble is int type of value 0x0200 and input is a float number. I'm compiling this with -m32 flag using gcc. Can someone point where I made mistake.

pushl %ebp
movl %esp,%ebp
finit                   
fldcw SetDouble          
fld input               
fld input
fmulp
fld1                    
faddp                   
fsqrt                   
fld1
fxch                    
fsubp
fstp output
mov %ebp,%esp 
pop %ebp

Answer 1

将控制字设置为 0x200 将 FPU 切换为双精度并取消屏蔽所有异常，包括精度异常。因此，对于大多数输入（可能除了 0 之外的所有输入）fsqrt都会引发此异常，这就是您所看到的。

您可以将控制字设置为 0x220 来屏蔽精度异常。