problem with crosstool 0.28-pre28 supplied patch for gcc 3.3.[23] softfloat on ARM

[Lennert Buytenhek]

(You're also Dutch?)


On Mon, Aug 16, 2004 at 02:23:54AM +0200, Dimitry Andric wrote:

> >         x = 1.0;
> >         printf("%f\n", x);
> [...]
> > [root@enp2611 tmp]# ./x
> > 0.000000
> [...]
> > If I try to print 1.1, I get "-0.000000".
> > If I try to print 1.2, I get "2.000000".
> > If I try to print 1.3, I get "-2.000000".
> > And if I try to print 1.4, I get (hang on)
> > "26815622249480124604215817416420243243587272560002206992098063765762173090970884294781200568594023450472595307446283091495952708613797907653947046282395648.000000"
> 
> > Maybe you have an idea off the top of your hat what's going wrong here?
> 
> I suppose this is what crosstool's patches/glibc-2.3.2/glibc-vfp.patch
> should fix.  Are you sure it is applied correctly?
> It seems that glibc interprets the float endianness incorrectly,
> thus printing garbage.

I think it's applied correctly?  I'm trying this with hardfloat, if
I use fpa or vfp softfloat it does print the right number.


> Can you try producing some .s files with your compiler, to see what it
> generates for the floating point constants?

OK, this:

<source>
#include <stdio.h>
#include <stdlib.h>

int main()
{
        volatile float x;

        x = 1.0;
        printf("%f\n", x);

        return 0;
}
</source>

gives me this:

<assembly>
        .file   "x.c"
        .section        .rodata.str1.4,"aMS",%progbits,1
        .align  2
.LC0:
        .ascii  "%f\n\000"
        .text
        .align  2
        .global main
        .type   main, %function
main:
        @ args = 0, pretend = 0, frame = 4
        @ frame_needed = 0, uses_anonymous_args = 0
        str     lr, [sp, #-4]!
        ldr     r3, .L2 @ float
        ldr     r0, .L2+4
        sub     sp, sp, #4
        str     r3, [sp, #0]    @ float
        ldfs    f1, [sp, #0]
        mvfd    f0, f1
        stfd    f0, [sp, #-8]!
        ldmfd   sp!, {r1, r2}
        bl      printf
        mov     r0, #0
        add     sp, sp, #4
        ldmfd   sp!, {pc}
.L3:
        .align  2
.L2:
        .word   1065353216
        .word   .LC0
        .size   main, .-main
        .ident  "GCC: (GNU) 3.4.1"
</assembly>


thanks,
Lennert

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