diff options
| author | law <law@138bc75d-0d04-0410-961f-82ee72b054a4> | 1999-10-15 04:50:09 +0000 |
|---|---|---|
| committer | law <law@138bc75d-0d04-0410-961f-82ee72b054a4> | 1999-10-15 04:50:09 +0000 |
| commit | 0e1e143e7727845141bf440a9ec2969f611accfb (patch) | |
| tree | 6884eb392c55198115c06f8cb78b15c8588568a1 /gcc/combine.c | |
| parent | 7546642c0a93d93246a02771866aac666609a6e3 (diff) | |
| download | gcc-0e1e143e7727845141bf440a9ec2969f611accfb.tar.gz | |
* fold-const.c (fold): Move bit_rotate code to the EXPR_PLUS case,
falltrought to assocate code.
Convert XOR to OR in code like (a&c1)^(a&c2) where c1 and c2 don't have
bits in common.
* combine.c (simplify_logical): Convert XOR to IOR if operands have
no bits in common; remove XOR to ROTATE conversion.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@29998 138bc75d-0d04-0410-961f-82ee72b054a4
Diffstat (limited to 'gcc/combine.c')
| -rw-r--r-- | gcc/combine.c | 23 |
1 files changed, 9 insertions, 14 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index a7b9c0c6d4a..7273e8f237e 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -5163,6 +5163,15 @@ simplify_logical (x, last) break; case XOR: + /* If we are XORing two things that have no bits in common, + convert them into an IOR. This helps to detect rotation encoded + using those methods and possibly other simplifications. */ + + if (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_WIDE_INT + && (nonzero_bits (op0, mode) + & nonzero_bits (op1, mode)) == 0) + return (gen_binary (IOR, mode, op0, op1)); + /* Convert (XOR (NOT x) (NOT y)) to (XOR x y). Also convert (XOR (NOT x) y) to (NOT (XOR x y)), similarly for (NOT y). */ @@ -5232,20 +5241,6 @@ simplify_logical (x, last) return gen_rtx_combine (reverse_condition (GET_CODE (op0)), mode, XEXP (op0, 0), XEXP (op0, 1)); - /* Convert (xor (ashift A CX) (lshiftrt A CY)) where CX+CY equals the - mode size to (rotate A CX). */ - - if (((GET_CODE (op0) == ASHIFT && GET_CODE (op1) == LSHIFTRT) - || (GET_CODE (op1) == ASHIFT && GET_CODE (op0) == LSHIFTRT)) - && rtx_equal_p (XEXP (op0, 0), XEXP (op1, 0)) - && GET_CODE (XEXP (op0, 1)) == CONST_INT - && GET_CODE (XEXP (op1, 1)) == CONST_INT - && (INTVAL (XEXP (op0, 1)) + INTVAL (XEXP (op1, 1)) - == GET_MODE_BITSIZE (mode))) - return gen_rtx_ROTATE (mode, XEXP (op0, 0), - (GET_CODE (op0) == ASHIFT - ? XEXP (op0, 1) : XEXP (op1, 1))); - break; default: |