On Wed, 2010-12-15 at 03:07 +0100, grischka wrote:
> Henry Kroll wrote:
> > x86_64 fails to copy the second struct passed to va_arg.
> >
> > static struct myspace {
> > short int profile;
> > } bob = { 42 };
> >
> > void badfunc(int eek, ...) {
> > va_list ack;
> > int validate;
> > struct myspace george, bill;
> > va_start(ack, eek);
> > bill = va_arg(ack, struct myspace);
> > george = va_arg(ack, struct myspace);
> > validate = va_arg(ack, int);
> > [...]
> > int main(int argc, char **argv) {
> > badfunc(0, bob, bob, bob.profile);
> > [...]
>
> This line from tcc's include/stdarg.h might give a hint:
> /* XXX: this lacks the support of aggregated types. */ \
>
> I have no idea though how such support would look like.
>
> Btw. on win64 it does not work either. I must have misunderstood
> something about the structures part of the calling conventions.
>
> --- grischka
>
>
> _______________________________________________
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This passes some hurried tests I threw at it, but I'm sure it needs more
type checking. I used the attached test program to generate a map of
ap->overflow_arg_area for various sized structures.
diff --git a/include/stdarg.h b/include/stdarg.h
index b5844d0..7b52d3d 100644
--- a/include/stdarg.h
+++ b/include/stdarg.h
@@ -39,8 +39,11 @@ typedef struct __va_list_struct *va_list;
: (ap->overflow_arg_area += 8, \
ap->overflow_arg_area - 8)) \
: (ap->gp_offset < 48 \
- ? (ap->gp_offset += 8, \
- ap->reg_save_area + ap->gp_offset - 8) \
+ ? __builtin_types_compatible_p(type, int) \
+ ? (ap->gp_offset += 8, \
+ ap->reg_save_area + ap->gp_offset - 8) \
+ : (ap->overflow_arg_area += (sizeof(type) + 3 & ~3), \
+ ap->overflow_arg_area - (sizeof(type) + 3 & ~3)) \
: (ap->overflow_arg_area += 8, \
ap->overflow_arg_area - 8)) \
))
#include <stdio.h>
#include <stdarg.h>
#define failed(what) do { \
printf("%i %s:%d: failure\n",what, __FILE__, __LINE__); \
errors++; \
} while (0)
static int errors = 0;
static struct myspace {
long double profile;
};
void badfunc(int eek, ...) {
va_list ack;
long int validate, i;
struct myspace bob, ned, sam;
va_start(ack, eek);
printf("Map of ack->overflow_arg_area:\n");
for (i=0;i<32;i++)
printf("%i ",*(ack->overflow_arg_area+i));
printf("\n");
bob = va_arg(ack, struct myspace);
ned = va_arg(ack, struct myspace);
sam = va_arg(ack, struct myspace);
validate = va_arg(ack, int);
if (bob.profile != 1) failed(bob.profile);
if (ned.profile != 2) failed(ned.profile);
if (sam.profile != 3) failed(sam.profile);
if (validate != 4) failed(validate);
va_end(ack);
}
int main(int argc, char **argv) {
struct myspace bob = {1};
struct myspace ned = {2};
struct myspace sam = {3};
badfunc(0, bob, ned, sam, 4);
return errors;
}
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