mirror/gcc
2
0
Fork 0
mirror of git://gcc.gnu.org/git/gcc.git synced 2025-01-11 09:04:32 +08:00
Code Issues Packages Projects Releases Wiki Activity

simplify-rtx.c (simplify_subreg): Remove useless shifts from word-extractions out of a multi-word object.

Browse Source 
2008-03-06  Paolo Bonzini  <bonzini@gnu.org>

	* simplify-rtx.c (simplify_subreg): Remove useless shifts from
	word-extractions out of a multi-word object.

From-SVN: r132971
This commit is contained in:
Paolo Bonzini 2008-03-06 13:30:10 +00:00 committed by Paolo Bonzini
parent fdc54e8854
commit 97efb03aed
2 changed files with 21 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
gcc/ChangeLog
View File

@ -1,3 +1,8 @@
2008-03-06 Paolo Bonzini <bonzini@gnu.org>
* simplify-rtx.c (simplify_subreg): Remove useless shifts from
word-extractions out of a multi-word object.
2008-03-06 Richard Guenther <rguenther@suse.de>
* tree.def (BIT_FIELD_REF): Constrain result type and its precision.

16
gcc/simplify-rtx.c
View File

@ -5239,6 +5239,22 @@ simplify_subreg (enum machine_mode outermode, rtx op,
return simplify_gen_binary (ASHIFT, outermode,
XEXP (XEXP (op, 0), 0), XEXP (op, 1));
/* Recognize a word extraction from a multi-word subreg. */
if ((GET_CODE (op) == LSHIFTRT
|| GET_CODE (op) == ASHIFTRT)
&& SCALAR_INT_MODE_P (outermode)
&& GET_MODE_BITSIZE (outermode) >= BITS_PER_WORD
&& GET_MODE_BITSIZE (innermode) >= (2 * GET_MODE_BITSIZE (outermode))
&& GET_CODE (XEXP (op, 1)) == CONST_INT
&& (INTVAL (XEXP (op, 1)) & (GET_MODE_BITSIZE (outermode) - 1)) == 0
&& byte == subreg_lowpart_offset (outermode, innermode))
{
int shifted_bytes = INTVAL (XEXP (op, 1)) / BITS_PER_UNIT;
return simplify_gen_subreg (outermode, XEXP (op, 0), innermode,
(WORDS_BIG_ENDIAN
? byte - shifted_bytes : byte + shifted_bytes));
}
return NULL_RTX;
}