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re PR middle-end/23477 (default-initializing array new expression uses makes stack usage go way up) 

2005-08-31  Richard Guenther  <rguenther@suse.de>

	PR middle-end/23477
	* expr.c (all_zeros_p): New function.
	(expand_expr_real_1): Handle the case of an all-zero
	non-addressable constructor separately.

From-SVN: r103670
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Richard Guenther 2005-08-31 11:20:38 +00:00 committed by Richard Biener
parent ef07d61bcb
commit c525013985
2 changed files with 38 additions and 0 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2005-08-31 Richard Guenther <rguenther@suse.de>
PR middle-end/23477
* expr.c (all_zeros_p): New function.
(expand_expr_real_1): Handle the case of an all-zero
non-addressable constructor separately.
2005-08-31 Adrian Straetling <straetling@de.ibm.com>
* builtins.c: (expand_builtin_strcpy, expand_builtin_strcat): Change

31
gcc/expr.c
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@ -4645,6 +4645,24 @@ mostly_zeros_p (tree exp)
return initializer_zerop (exp);
}
/* Return 1 if EXP contains all zeros. */
static int
all_zeros_p (tree exp)
{
if (TREE_CODE (exp) == CONSTRUCTOR)
{
HOST_WIDE_INT nz_elts, nc_elts, count;
bool must_clear;
categorize_ctor_elements (exp, &nz_elts, &nc_elts, &count, &must_clear);
return nz_elts == 0;
}
return initializer_zerop (exp);
}
/* Helper function for store_constructor.
TARGET, BITSIZE, BITPOS, MODE, EXP are as for store_field.
@ -6843,6 +6861,19 @@ expand_expr_real_1 (tree exp, rtx target, enum machine_mode tmode,
return const0_rtx;
}
/* Try to avoid creating a temporary at all. This is possible
if all of the initializer is zero.
FIXME: try to handle all [0..255] initializers we can handle
with memset. */
else if (TREE_STATIC (exp)
&& !TREE_ADDRESSABLE (exp)
&& target != 0 && mode == BLKmode
&& all_zeros_p (exp))
{
clear_storage (target, expr_size (exp), BLOCK_OP_NORMAL);
return target;
}
/* All elts simple constants => refer to a constant in memory. But
if this is a non-BLKmode mode, let it store a field at a time
since that should make a CONST_INT or CONST_DOUBLE when we