To put your mind at rest, try this example:
double barf (int n, double k)
{
double m = (double)n*k;
try
{
double b = (double)(n/n);
if (b !=0)
return 1;
}
catch (...)
{
}
return m;
}
This is the code at -O2, the code on the right is the one with
-fnon-call-exceptions. Note how in the latter case gcc stashes the
value for m on the stack.
Andrew.
.globl barf(int, double) .globl barf(int, double)
.type barf(int, double), @function .type barf(int, double), @function
barf(int, double): barf(int, double):
.LFB2: .LFB2:
pushl %ebp # pushl %ebp #
.LCFI0: .LCFI0:
movl %esp, %ebp #, movl %esp, %ebp #,
.LCFI1: .LCFI1:
> .LEHB0:
> subl $24, %esp #,
> .LCFI2:
movl 8(%ebp), %eax # n, n movl 8(%ebp), %eax # n, n
pushl %eax # n <
cltd cltd
idivl %eax # n | pushl %eax # n
fildl (%esp) # fildl (%esp) #
> addl $4, %esp #,
fmull 12(%ebp) # k fmull 12(%ebp) # k
movl %eax, (%esp) # tmp65, | .LEHE0:
> fstpl -8(%ebp) # m
> .LEHB1:
> idivl %eax # n
> pushl %eax # tmp65
fildl (%esp) # fildl (%esp) #
addl $4, %esp #, | .LEHE1:
fldz fldz
fxch %st(1) # fxch %st(1) #
> addl $4, %esp #,
> .LEHB2:
fucompp fucompp
fnstsw %ax # fnstsw %ax #
sahf sahf
jp .L12 #, | jp .L13 #,
jne .L12 #, | jne .L13 #,
> fldl -8(%ebp) # m
> leave
> .p2align 4,,15
> .L16:
> ret
> .p2align 4,,7
> .L11:
.L5: .L5:
.L6: .L6:
popl %ebp # | .L8:
ret | movl %eax, (%esp) # tmp69,
.L12: | call __cxa_begin_catch #
fstp %st(0) # | call __cxa_end_catch #
popl %ebp # | fldl -8(%ebp) # m
> leave
> jmp .L16 #
> .L13:
> leave
> .LEHE2:
fld1 fld1
ret ret
.LFE2: .LFE2: