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| author | Richard Henderson <rth@cygnus.com> | 2000-09-18 11:39:03 -0700 |
|---|---|---|
| committer | Richard Henderson <rth@gcc.gnu.org> | 2000-09-18 11:39:03 -0700 |
| commit | 9f8e169eb7a21b2f374df31dd32beef667676a13 (patch) | |
| tree | e5368a85baba02b2ff951b82f3c658f9d223df6c /gcc/combine.c | |
| parent | 1f3f36d154896f68c1c35420121782ed236da177 (diff) | |
| download | gcc-9f8e169eb7a21b2f374df31dd32beef667676a13.zip gcc-9f8e169eb7a21b2f374df31dd32beef667676a13.tar.gz gcc-9f8e169eb7a21b2f374df31dd32beef667676a13.tar.bz2 | |
combine.c (simplify_comparison): Shift a NOT out of a single bit test.
* combine.c (simplify_comparison): Shift a NOT out of a single
bit test.
From-SVN: r36508
Diffstat (limited to 'gcc/combine.c')
| -rw-r--r-- | gcc/combine.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index b8ac09b..a498b58 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -10811,6 +10811,21 @@ simplify_comparison (code, pop0, pop1) continue; } + /* Convert (ne (and (lshiftrt (not X)) 1) 0) to + (eq (and (lshiftrt X) 1) 0). */ + 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) + { + op0 = simplify_and_const_int + (op0, mode, gen_rtx_combine (LSHIFTRT, mode, + XEXP (XEXP (XEXP (op0, 0), 0), 0), + XEXP (XEXP (op0, 0), 1)), + (HOST_WIDE_INT) 1); + code = (code == NE ? EQ : NE); + continue; + } break; case ASHIFT: |