[PATCH] Reduce memory required by build_string

[Richard Guenther]

On Mon, 26 Jun 2006, Richard Guenther wrote:

> On Mon, 26 Jun 2006, Jakub Jelinek wrote:
> 
> > > ! 
> > > !   /* Do not waste bytes provided by padding of struct tree_string.  */
> > > !   length = ((len + sizeof (struct tree_string))
> > > ! 	    & ~(sizeof (struct tree_string)
> > > ! 		- offsetof (struct tree_string, str) - 1));
> > 
> > How do you know that sizeof (struct tree_string) - offsetof (struct tree_string, str)
> > is a power of two?
> 
> Only by looking at the struct definition, so yes, you are right.
> 
> > I think
> >   length = len + offsetof (struct tree_string, str);
> > would be much better.
> 
> No, but
> 
>  length = len + offsetof (struct tree_string, str) + 1;
> 
> would work, indeed.  Re-running bootstrap & regtest with this.

Bootstrapped and tested on x86_64-unknown-linux-gnu.

Ok for mainline?

Thanks,
Richard.

2006-06-26  Richard Guenther  <rguenther@suse.de>

	* tree.c (build_string): Do not waste tail padding in
	struct tree_string.

Index: tree.c
===================================================================
*** tree.c	(revision 115006)
--- tree.c	(working copy)
*************** build_string (int len, const char *str)
*** 1120,1127 ****
  {
    tree s;
    size_t length;
!   
!   length = len + sizeof (struct tree_string);
  
  #ifdef GATHER_STATISTICS
    tree_node_counts[(int) c_kind]++;
--- 1120,1128 ----
  {
    tree s;
    size_t length;
! 
!   /* Do not waste bytes provided by padding of struct tree_string.  */
!   length = len + offsetof (struct tree_string, str) + 1;
  
  #ifdef GATHER_STATISTICS
    tree_node_counts[(int) c_kind]++;