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expr.c (get_inner_reference): Do computation of bitoffset from offset in a way we can detect overflow reliably.

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2007-08-23  Richard Guenther  <rguenther@suse.de>

	* expr.c (get_inner_reference): Do computation of bitoffset
	from offset in a way we can detect overflow reliably.

From-SVN: r127762
This commit is contained in:
Richard Guenther 2007-08-24 09:41:17 +00:00 committed by Richard Biener
parent 1651030c42
commit 9c219b9bb3
2 changed files with 25 additions and 12 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
2007-08-24 Richard Guenther <rguenther@suse.de>
* expr.c (get_inner_reference): Do computation of bitoffset
from offset in a way we can detect overflow reliably.
2007-08-24 Jie Zhang <jie.zhang@analog.com>
* crtstuff.c (USE_PT_GNU_EH_FRAME): Don't define for uClibc.

32
gcc/expr.c
View File

@ -5782,7 +5782,6 @@ get_inner_reference (tree exp, HOST_WIDE_INT *pbitsize,
enum machine_mode mode = VOIDmode;
tree offset = size_zero_node;
tree bit_offset = bitsize_zero_node;
tree tem;
/* First get the mode, signedness, and size. We do this from just the
outermost expression. */
@ -5825,6 +5824,8 @@ get_inner_reference (tree exp, HOST_WIDE_INT *pbitsize,
*pbitsize = tree_low_cst (size_tree, 1);
}
*pmode = mode;
/* Compute cumulative bit-offset for nested component-refs and array-refs,
and find the ultimate containing object. */
while (1)
@ -5909,18 +5910,25 @@ get_inner_reference (tree exp, HOST_WIDE_INT *pbitsize,
done:
/* If OFFSET is constant, see if we can return the whole thing as a
constant bit position. Otherwise, split it up. */
if (host_integerp (offset, 0)
&& 0 != (tem = size_binop (MULT_EXPR,
fold_convert (bitsizetype, offset),
bitsize_unit_node))
&& 0 != (tem = size_binop (PLUS_EXPR, tem, bit_offset))
&& host_integerp (tem, 0))
*pbitpos = tree_low_cst (tem, 0), *poffset = 0;
else
*pbitpos = tree_low_cst (bit_offset, 0), *poffset = offset;
constant bit position. Make sure to handle overflow during
this conversion. */
if (host_integerp (offset, 0))
{
double_int tem = double_int_mul (tree_to_double_int (offset),
uhwi_to_double_int (BITS_PER_UNIT));
tem = double_int_add (tem, tree_to_double_int (bit_offset));
if (double_int_fits_in_shwi_p (tem))
{
*pbitpos = double_int_to_shwi (tem);
*poffset = NULL_TREE;
return exp;
}
}
/* Otherwise, split it up. */
*pbitpos = tree_low_cst (bit_offset, 0);
*poffset = offset;
*pmode = mode;
return exp;
}