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combine.c (simplify_comparison): Convert (ne (and (lshiftrt (xor X CST) Y) 1) 0) into (eq (and (lshiftrt X Y) 1) 0). 

* combine.c (simplify_comparison): Convert
	(ne (and (lshiftrt (xor X CST) Y) 1) 0) into
	(eq (and (lshiftrt X Y) 1) 0).

From-SVN: r71385
This commit is contained in:
Kazu Hirata 2003-09-14 18:31:13 +00:00 committed by Kazu Hirata
parent 83a00410f5
commit 5565e8744f
2 changed files with 27 additions and 10 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2003-09-14 Kazu Hirata <kazu@cs.umass.edu>
* combine.c (simplify_comparison): Convert
(ne (and (lshiftrt (xor X CST) Y) 1) 0) into
(eq (and (lshiftrt X Y) 1) 0).
2003-09-14 Kazu Hirata <kazu@cs.umass.edu>
* alias.c: Follow spelling conventions.

31
gcc/combine.c
View File

@ -10983,19 +10983,30 @@ simplify_comparison (enum rtx_code code, rtx *pop0, rtx *pop1)
}
/* Convert (ne (and (lshiftrt (not X)) 1) 0) to
(eq (and (lshiftrt X) 1) 0). */
(eq (and (lshiftrt X) 1) 0).
Also handle the case where (not X) is expressed using xor. */
if (const_op == 0 && equality_comparison_p
&& XEXP (op0, 1) == const1_rtx
&& GET_CODE (XEXP (op0, 0)) == LSHIFTRT
&& GET_CODE (XEXP (XEXP (op0, 0), 0)) == NOT)
&& GET_CODE (XEXP (op0, 0)) == LSHIFTRT)
{
op0 = simplify_and_const_int
(op0, mode,
gen_rtx_LSHIFTRT (mode, XEXP (XEXP (XEXP (op0, 0), 0), 0),
XEXP (XEXP (op0, 0), 1)),
(HOST_WIDE_INT) 1);
code = (code == NE ? EQ : NE);
continue;
rtx shift_op = XEXP (XEXP (op0, 0), 0);
rtx shift_count = XEXP (XEXP (op0, 0), 1);
if (GET_CODE (shift_op) == NOT
|| (GET_CODE (shift_op) == XOR
&& GET_CODE (XEXP (shift_op, 1)) == CONST_INT
&& GET_CODE (shift_count) == CONST_INT
&& GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT
&& (INTVAL (XEXP (shift_op, 1))
== (HOST_WIDE_INT) 1 << INTVAL (shift_count))))
{
op0 = simplify_and_const_int
(NULL_RTX, mode,
gen_rtx_LSHIFTRT (mode, XEXP (shift_op, 0), shift_count),
(HOST_WIDE_INT) 1);
code = (code == NE ? EQ : NE);
continue;
}
}
break;