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[PATCH] Fix DECL_ALIGN during expand with dynamic stack realignment (PR target/44542, take 2)
On Thu, Jun 17, 2010 at 04:52:38PM +0200, Michael Matz wrote:
> > + else if (DECL_HAS_VALUE_EXPR_P (var)
> > + || (DECL_RTL_SET_P (var)
> > + && MEM_P (DECL_RTL (var))
> > + && (XEXP (DECL_RTL (var), 0) == virtual_stack_vars_rtx
> > + || (GET_CODE (XEXP (DECL_RTL (var), 0)) == PLUS
> > + && XEXP (XEXP (DECL_RTL (var), 0), 0)
> > + == virtual_stack_vars_rtx
> > + && CONST_INT_P (XEXP (XEXP (DECL_RTL (var), 0), 1))))))
>
> ... this reads uneasy to me (that's the reason I bothered with the
> really_expand suggestion). Why do you have to test the form of the MEM,
> shouldn't "DECL_RTL_SET_P (var) && MEM_P (DECL_RTL (var))" be enough, or
> even without testing for MEM_P?
During testing with assert of this I found that Ada passes in through
some VAR_DECLs with (mem (sp)), but those shouldn't matter for dynamic stack
realignment purposes.
So here is an updated patch (also with the align == 0 -> max_align stuff
H.J. mentioned), bootstrapped/regtested on x86_64-linux and i686-linux.
Ok for trunk?
2010-06-17 Jakub Jelinek <jakub@redhat.com>
PR target/44542
* cfgexpand.c (expand_one_stack_var_at): Limit align to maximum
of max_used_stack_slot_alignment and PREFERRED_STACK_BOUNDARY
instead of MAX_SUPPORTED_STACK_ALIGNMENT.
(expand_one_var): Don't consider DECL_ALIGN for variables for
which expand_one_stack_var_at has been already called.
--- gcc/cfgexpand.c.jj 2010-06-17 17:01:11.964198458 +0200
+++ gcc/cfgexpand.c 2010-06-17 18:25:18.940335757 +0200
@@ -706,7 +706,7 @@ static void
expand_one_stack_var_at (tree decl, HOST_WIDE_INT offset)
{
/* Alignment is unsigned. */
- unsigned HOST_WIDE_INT align;
+ unsigned HOST_WIDE_INT align, max_align;
rtx x;
/* If this fails, we've overflowed the stack frame. Error nicely? */
@@ -723,10 +723,10 @@ expand_one_stack_var_at (tree decl, HOST
offset -= frame_phase;
align = offset & -offset;
align *= BITS_PER_UNIT;
- if (align == 0)
- align = STACK_BOUNDARY;
- else if (align > MAX_SUPPORTED_STACK_ALIGNMENT)
- align = MAX_SUPPORTED_STACK_ALIGNMENT;
+ max_align = MAX (crtl->max_used_stack_slot_alignment,
+ PREFERRED_STACK_BOUNDARY);
+ if (align == 0 || align > max_align)
+ align = max_align;
DECL_ALIGN (decl) = align;
DECL_USER_ALIGN (decl) = 0;
@@ -931,6 +931,13 @@ expand_one_var (tree var, bool toplevel,
align = MINIMUM_ALIGNMENT (TREE_TYPE (var),
TYPE_MODE (TREE_TYPE (var)),
TYPE_ALIGN (TREE_TYPE (var)));
+ else if (DECL_HAS_VALUE_EXPR_P (var)
+ || (DECL_RTL_SET_P (var) && MEM_P (DECL_RTL (var))))
+ /* Don't consider debug only variables with DECL_HAS_VALUE_EXPR_P set
+ or variables which were assigned a stack slot already by
+ expand_one_stack_var_at - in the latter case DECL_ALIGN has been
+ changed from the offset chosen to it. */
+ align = crtl->stack_alignment_estimated;
else
align = MINIMUM_ALIGNMENT (var, DECL_MODE (var), DECL_ALIGN (var));
Jakub