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| author | Michael Matz <matz@suse.de> | 2016-11-15 14:02:28 +0000 |
|---|---|---|
| committer | Michael Matz <matz@gcc.gnu.org> | 2016-11-15 14:02:28 +0000 |
| commit | b229ab2a712ccd44126bcbcaed2da8b998e7366c (patch) | |
| tree | 6332e06f8a024d08d976fc3a4dcd33711ea2e615 /gcc/combine.c | |
| parent | aa806c3be702a6bcd72cad5c329024ee68e29e3a (diff) | |
| download | gcc-b229ab2a712ccd44126bcbcaed2da8b998e7366c.zip gcc-b229ab2a712ccd44126bcbcaed2da8b998e7366c.tar.gz gcc-b229ab2a712ccd44126bcbcaed2da8b998e7366c.tar.bz2 | |
re PR target/77881 (Non-optimal signed comparison on x86_64 since r146817)
PR missed-optimization/77881
* combine.c (simplify_comparison): Remove useless subregs
also inside the loop, not just after it.
(make_compound_operation): Recognize some subregs as being
masking as well.
testsuite/
* gcc.target/i386/pr77881.c: New test.
From-SVN: r242414
Diffstat (limited to 'gcc/combine.c')
| -rw-r--r-- | gcc/combine.c | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index 6b7bdd0..2de2a3e 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -8102,6 +8102,18 @@ make_compound_operation (rtx x, enum rtx_code in_code) rtx inner = SUBREG_REG (x), simplified; enum rtx_code subreg_code = in_code; + /* If the SUBREG is masking of a logical right shift, + make an extraction. */ + if (GET_CODE (inner) == LSHIFTRT + && GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (inner)) + && subreg_lowpart_p (x)) + { + new_rtx = make_compound_operation (XEXP (inner, 0), next_code); + new_rtx = make_extraction (mode, new_rtx, 0, XEXP (inner, 1), + mode_width, 1, 0, in_code == COMPARE); + break; + } + /* If in_code is COMPARE, it isn't always safe to pass it through to the recursive make_compound_operation call. */ if (subreg_code == COMPARE @@ -11994,6 +12006,29 @@ simplify_comparison (enum rtx_code code, rtx *pop0, rtx *pop1) if (subreg_lowpart_p (op0) && GET_MODE_PRECISION (GET_MODE (SUBREG_REG (op0))) < mode_width) ; + else if (subreg_lowpart_p (op0) + && GET_MODE_CLASS (GET_MODE (op0)) == MODE_INT + && GET_MODE_CLASS (GET_MODE (SUBREG_REG (op0))) == MODE_INT + && (code == NE || code == EQ) + && (GET_MODE_PRECISION (GET_MODE (SUBREG_REG (op0))) + <= HOST_BITS_PER_WIDE_INT) + && !paradoxical_subreg_p (op0) + && (nonzero_bits (SUBREG_REG (op0), + GET_MODE (SUBREG_REG (op0))) + & ~GET_MODE_MASK (GET_MODE (op0))) == 0) + { + /* Remove outer subregs that don't do anything. */ + tem = gen_lowpart (GET_MODE (SUBREG_REG (op0)), op1); + + if ((nonzero_bits (tem, GET_MODE (SUBREG_REG (op0))) + & ~GET_MODE_MASK (GET_MODE (op0))) == 0) + { + op0 = SUBREG_REG (op0); + op1 = tem; + continue; + } + break; + } else break; |