[PATCH] Fix PR56344

Marek Polacek polacek@redhat.com
Wed Feb 27 09:56:00 GMT 2013


On Tue, Feb 26, 2013 at 11:17:22PM +0000, Joseph S. Myers wrote:
> On Tue, 26 Feb 2013, Marek Polacek wrote:
> 
> > +	      /* We don't allow passing huge (> 2^30 B) arguments
> > +	         by value.  It would cause an overflow later on.  */
> > +	      if (adjusted_args_size.constant >= (1 << 30))
> > +	        {
> > +	          error ("passing too large argument on stack");
> > +		  continue;
> 
> This should be sorry () not error (), as a compiler limitation rather than 
> a defect in the user's program.  (And is input_location set to something 
> useful here so the diagnostic points to the argument in question rather 
> than e.g. to the end of the function containing the problem call?)

Okay, changed back to sorry ().  I'd think that input_location is fine
here, for e.g.

struct S { unsigned char s[1 << 30]; } s;
extern void foo (struct S);

void
bar (void)
{
  foo (s);
}

we get:
pr56344.c: In function ‘bar’:
pr56344.c:7:7: sorry, unimplemented: passing too large argument on stack
   foo (s);
       ^

Ok now?

2013-02-27  Marek Polacek  <polacek@redhat.com>

	PR middle-end/56344
	* calls.c (expand_call): Disallow passing huge arguments
	by value.

--- gcc/calls.c.mp	2013-02-26 17:04:33.159555349 +0100
+++ gcc/calls.c	2013-02-27 10:44:02.254461200 +0100
@@ -3037,6 +3037,14 @@ expand_call (tree exp, rtx target, int i
 	    {
 	      rtx before_arg = get_last_insn ();
 
+	      /* We don't allow passing huge (> 2^30 B) arguments
+	         by value.  It would cause an overflow later on.  */
+	      if (adjusted_args_size.constant >= (1 << 30))
+	        {
+	          sorry ("passing too large argument on stack");
+		  continue;
+		}
+
 	      if (store_one_arg (&args[i], argblock, flags,
 				 adjusted_args_size.var != 0,
 				 reg_parm_stack_space)

	Marek



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