diff options
| 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 | |
| parent | aa806c3be702a6bcd72cad5c329024ee68e29e3a (diff) | |
| download | gcc-b229ab2a712ccd44126bcbcaed2da8b998e7366c.tar.gz | |
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
| -rw-r--r-- | gcc/ChangeLog | 8 | ||||
| -rw-r--r-- | gcc/combine.c | 35 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.target/i386/pr77881.c | 12 |
4 files changed, 60 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 1e422d2a844..c4a660f0cff 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,11 @@ +2016-11-15 Michael Matz <matz@suse.de> + + 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. + 2016-11-15 Richard Sandiford <richard.sandiford@arm.com> Alan Hayward <alan.hayward@arm.com> David Sherwood <david.sherwood@arm.com> diff --git a/gcc/combine.c b/gcc/combine.c index 6b7bdd0f687..2de2a3ef8a2 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; diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index fce6f8d1b8f..dcb220d036a 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2016-11-15 Michael Matz <matz@suse.de> + + PR missed-optimization/77881 + * gcc.target/i386/pr77881.c: New test. + 2016-11-15 Jakub Jelinek <jakub@redhat.com> PR middle-end/78295 diff --git a/gcc/testsuite/gcc.target/i386/pr77881.c b/gcc/testsuite/gcc.target/i386/pr77881.c new file mode 100644 index 00000000000..80d143f2bc5 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr77881.c @@ -0,0 +1,12 @@ +/* { dg-do compile } */ +/* { dg-require-effective-target pie } */ +/* { dg-options "-O2" } */ +extern void baz(void); +int +foo (long long int a, long long int a2, int b) +{ + if (a < 0 || b) + baz (); +} +/* { dg-final { scan-assembler "js\[ \t\]\.L" } } */ +/* { dg-final { scan-assembler "jne\[ \t\]\.L" } } */ |