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| author | Segher Boessenkool <segher@kernel.crashing.org> | 2016-11-23 15:33:13 +0100 |
|---|---|---|
| committer | Segher Boessenkool <segher@gcc.gnu.org> | 2016-11-23 15:33:13 +0100 |
| commit | 712871dde1fb2d29b4f742fababb645cd3b1dbbe (patch) | |
| tree | 35a38cefb14ddb97781f6cba2e1483e9cc17ac3c /gcc/combine.c | |
| parent | 33951763a85087927068d553be6709cd03953a09 (diff) | |
| download | gcc-712871dde1fb2d29b4f742fababb645cd3b1dbbe.zip gcc-712871dde1fb2d29b4f742fababb645cd3b1dbbe.tar.gz gcc-712871dde1fb2d29b4f742fababb645cd3b1dbbe.tar.bz2 | |
combine: Convert subreg-of-lshiftrt to zero_extract properly (PR78390)
r242414, for PR77881, introduces some bugs (PR78390, PR78438, PR78477).
It all has the same root cause: that patch makes combine convert every
lowpart subreg of a logical shift right to a zero_extract. This cannot
work at all if it is not a constant shift, and it has to be a bit more
careful exactly which bits it extracts.
PR target/77881
PR bootstrap/78390
PR target/78438
PR bootstrap/78477
* combine.c (make_compound_operation_int): Do not convert a subreg of
a non-constant logical shift right to a zero_extract. Handle the case
where some zero bits have been shifted into the range covered by that
subreg.
From-SVN: r242757
Diffstat (limited to 'gcc/combine.c')
| -rw-r--r-- | gcc/combine.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index 93621bd..ae25ef3 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -8089,12 +8089,17 @@ make_compound_operation_int (machine_mode mode, rtx *x_ptr, /* If the SUBREG is masking of a logical right shift, make an extraction. */ if (GET_CODE (inner) == LSHIFTRT + && CONST_INT_P (XEXP (inner, 1)) && GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (inner)) && subreg_lowpart_p (x)) { new_rtx = make_compound_operation (XEXP (inner, 0), next_code); + int width = GET_MODE_PRECISION (GET_MODE (inner)) + - INTVAL (XEXP (inner, 1)); + if (width > mode_width) + width = mode_width; new_rtx = make_extraction (mode, new_rtx, 0, XEXP (inner, 1), - mode_width, 1, 0, in_code == COMPARE); + width, 1, 0, in_code == COMPARE); break; } |