Re: where does gcc generate float param passing code be

["add" <addsub at eyou dot com>]

sorry for my testcase, I had rewriten it to easy to understand, but on the
contrary...
Here is my true test case using printf:
----main.c
#include <stdio.h>
#include <stdlib.h>

int main()
{
        float i=1.0;
        printf("%f",i);
        return 0;
}
----main.c

here is generated by arm-linux-gcc -S main.c -o main.s
----main.s
<sniz>
main:
          @ args = 0, pretend = 0, frame = 4
          @ frame_needed = 1, uses_anonymous_args = 0
          mov     ip, sp
          stmfd   sp!, {r4, fp, ip, lr, pc}
          sub     fp, ip, #4
          sub     sp, sp, #4
          ldr     r3, .L2 @ float
          str     r3, [fp, #-20]  @ float
          ldr     r0, [fp, #-20]  @ float
          bl      __extendsfdf2
          mov     r4, r1
          mov     r3, r0
          ldr     r0, .L2+4
          mov     r2, r4
          mov     r1, r3
          bl      printf
          mov     r3, #0
          mov     r0, r3
<sniz>
-----main.s

if I arm-linux-gcc main.s -o test
then execute test on pxa board, it will output: -1.999744

but if I modified the two lines before "bl printf" in main.s to:
mov	r2, r3
mov	r3, r4
then compile main.s and execute,
it will print right result: 1.00000

so conclusion:
my toolchain must has a problem of float param passing, so I want to dig into
my gcc source tree to find where is responsible for generating this wrong asm
code.
I hope this time it's clearer :)
>Hi add,
>
>What we have here is "GIGO".  Garbage in, garbage out.
>
>Try this instead:
>- - - - - - - - - - - - - - - -
>double foo( double i )
>{
>        return i;
>}
>int main()
>{
>        double i=1.0;
>        foo(i);
>        return 0;
>}
>- - - - - - - - - - - - - - - -
>
>Note all the differences, there are quite a few.  Order is important. 
Details are important.
>
>HTH,
>--Eljay 
>
> 





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