Re: Still problems with alloca and frame layout on w64 targets

[Kai Tietz <Kai.Tietz@onevision.com>]

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> Hi,
> 
> this small c program produces wrong code on x86_64-pc-mingw32. The 
problem 
> here is the call abi w64. For w64 call abi, the last reserved 32 bytes 
on 
> stack are use for vaarg functions to save the incoming arguments from 
> register. This works fine as long as there is no alloca call within the 
> function calling a vaarg method. The alloca reserves just the stack, but 

> does not move the stack clobber region. So by a vaarg call the last 
> reserved stack is clobbered.
> 
> How and where can I solve this problem?

Sorry I attached wrong testcase

Thanks in advance,
Kai



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[-- Attachment #2: test.c --]
[-- Type: application/octet-stream, Size: 616 bytes --]

#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
#include <stdarg.h>

void do_zero (int argc, ...)
{
  va_list argp;
  char *c;
  va_start(argp, argc);
  while ((c=va_arg(argp,char *))!=NULL)
    memset(c,0,argc);
  va_end (argp);
}

void do_print (const char *fmt, const char *h,int s)
{
  int i;
  for (i=0;h[i]==0 && i<s;i++);
  if (i!=s) abort ();
}

int main (int argc,char **argv)
{
  char *a,*b;
  a = (char *) alloca (argc * 32);
  do_zero (argc * 32,a,NULL);
  b = (char *) alloca (argc * 32);
  do_zero (argc * 32,b,NULL);
  do_print ("a",a,argc * 32);
  do_print ("a",b,argc * 32);
  return 0;
}