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combine.c (simplify_and_const_int): Simplify (AND (PLUS X Y) C) if C has only low bits set and doesn't intersect...

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* combine.c (simplify_and_const_int): Simplify (AND (PLUS X Y) C)
        if C has only low bits set and doesn't intersect with X or Y.

From-SVN: r47921
This commit is contained in:
Richard Henderson 2001-12-11 21:58:12 -08:00 • committed by Richard Henderson
parent 3dba42519e
commit 8deb751450
2 changed files with 22 additions and 0 deletions
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gcc/ChangeLog
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@ -1,3 +1,8 @@
2001-12-11 Richard Henderson <rth@redhat.com>
* combine.c (simplify_and_const_int): Simplify (AND (PLUS X Y) C)
if C has only low bits set and doesn't intersect with X or Y.
Tue Dec 11 23:58:39 EST 2001 John Wehle (john@feith.com)
* basic-block.h (flow_preorder_transversal_compute): Declare.

17
gcc/combine.c
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@ -7791,6 +7791,23 @@ simplify_and_const_int (x, mode, varop, constop)
simplify_and_const_int (NULL_RTX, GET_MODE (varop),
XEXP (varop, 1), constop))));
/* If VAROP is PLUS, and the constant is a mask of low bite, distribute
the AND and see if one of the operands simplifies to zero. If so, we
may eliminate it. */
if (GET_CODE (varop) == PLUS
&& exact_log2 (constop + 1) >= 0)
{
rtx o0, o1;
o0 = simplify_and_const_int (NULL_RTX, mode, XEXP (varop, 0), constop);
o1 = simplify_and_const_int (NULL_RTX, mode, XEXP (varop, 1), constop);
if (o0 == const0_rtx)
return o1;
if (o1 == const0_rtx)
return o0;
}
/* Get VAROP in MODE. Try to get a SUBREG if not. Don't make a new SUBREG
if we already had one (just check for the simplest cases). */
if (x && GET_CODE (XEXP (x, 0)) == SUBREG