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stor-layout.c (bit_from_pos): Document. 

2012-05-09  Richard Guenther  <rguenther@suse.de>

	* stor-layout.c (bit_from_pos): Document.
	(byte_from_pos): Likewise.  Optimize.
	(pos_from_bit): Likewise.
	(normalize_offset): Use pos_from_bit instead of replicating it.

From-SVN: r187317
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Richard Guenther 2012-05-09 08:56:25 +00:00 committed by Richard Biener
parent 570a374aa5
commit 2af273018e
2 changed files with 44 additions and 23 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2012-05-09 Richard Guenther <rguenther@suse.de>
* stor-layout.c (bit_from_pos): Document.
(byte_from_pos): Likewise. Optimize.
(pos_from_bit): Likewise.
(normalize_offset): Use pos_from_bit instead of replicating it.
2012-05-09 Alan Modra <amodra@gmail.com>
PR target/53271

60
gcc/stor-layout.c
View File

@ -785,8 +785,8 @@ start_record_layout (tree t)
return rli;
}
/* These four routines perform computations that convert between
the offset/bitpos forms and byte and bit offsets. */
/* Return the combined bit position for the byte offset OFFSET and the
bit position BITPOS. */
tree
bit_from_pos (tree offset, tree bitpos)
@ -797,25 +797,46 @@ bit_from_pos (tree offset, tree bitpos)
bitsize_unit_node));
}
/* Return the combined truncated byte position for the byte offset OFFSET and
the bit position BITPOS. */
tree
byte_from_pos (tree offset, tree bitpos)
{
return size_binop (PLUS_EXPR, offset,
fold_convert (sizetype,
size_binop (TRUNC_DIV_EXPR, bitpos,
bitsize_unit_node)));
tree bytepos;
if (TREE_CODE (bitpos) == MULT_EXPR
&& tree_int_cst_equal (TREE_OPERAND (bitpos, 1), bitsize_unit_node))
bytepos = TREE_OPERAND (bitpos, 0);
else
bytepos = size_binop (TRUNC_DIV_EXPR, bitpos, bitsize_unit_node);
return size_binop (PLUS_EXPR, offset, fold_convert (sizetype, bytepos));
}
/* Split the bit position POS into a byte offset *POFFSET and a bit
position *PBITPOS with the byte offset aligned to OFF_ALIGN bits. */
void
pos_from_bit (tree *poffset, tree *pbitpos, unsigned int off_align,
tree pos)
{
*poffset = size_binop (MULT_EXPR,
fold_convert (sizetype,
size_binop (FLOOR_DIV_EXPR, pos,
bitsize_int (off_align))),
size_int (off_align / BITS_PER_UNIT));
*pbitpos = size_binop (FLOOR_MOD_EXPR, pos, bitsize_int (off_align));
tree toff_align = bitsize_int (off_align);
if (TREE_CODE (pos) == MULT_EXPR
&& tree_int_cst_equal (TREE_OPERAND (pos, 1), toff_align))
{
*poffset = size_binop (MULT_EXPR,
fold_convert (sizetype, TREE_OPERAND (pos, 0)),
size_int (off_align / BITS_PER_UNIT));
*pbitpos = bitsize_zero_node;
}
else
{
*poffset = size_binop (MULT_EXPR,
fold_convert (sizetype,
size_binop (FLOOR_DIV_EXPR, pos,
toff_align)),
size_int (off_align / BITS_PER_UNIT));
*pbitpos = size_binop (FLOOR_MOD_EXPR, pos, toff_align);
}
}
/* Given a pointer to bit and byte offsets and an offset alignment,
@ -828,17 +849,10 @@ normalize_offset (tree *poffset, tree *pbitpos, unsigned int off_align)
downwards. */
if (compare_tree_int (*pbitpos, off_align) >= 0)
{
tree extra_aligns = size_binop (FLOOR_DIV_EXPR, *pbitpos,
bitsize_int (off_align));
*poffset
= size_binop (PLUS_EXPR, *poffset,
size_binop (MULT_EXPR,
fold_convert (sizetype, extra_aligns),
size_int (off_align / BITS_PER_UNIT)));
*pbitpos
= size_binop (FLOOR_MOD_EXPR, *pbitpos, bitsize_int (off_align));
tree offset, bitpos;
pos_from_bit (&offset, &bitpos, off_align, *pbitpos);
*poffset = size_binop (PLUS_EXPR, *poffset, offset);
*pbitpos = bitpos;
}
}