diff options
| author | Richard Henderson <rth@redhat.com> | 2016-01-31 23:32:01 -0800 |
|---|---|---|
| committer | Richard Henderson <rth@gcc.gnu.org> | 2016-01-31 23:32:01 -0800 |
| commit | e6c0c44b5b43c4fef77f3a566d035db5c589ff99 (patch) | |
| tree | 1a823e636b4518bcd0082dd43b0cca0e2f504118 /gcc/combine.c | |
| parent | 2c0055380610a6430b885a2312175b71a47527a3 (diff) | |
| download | gcc-e6c0c44b5b43c4fef77f3a566d035db5c589ff99.zip gcc-e6c0c44b5b43c4fef77f3a566d035db5c589ff99.tar.gz gcc-e6c0c44b5b43c4fef77f3a566d035db5c589ff99.tar.bz2 | |
re PR rtl-optimization/69535 (wrong code with -O -fno-tree-bit-ccp -fno-tree-reassoc due to use of uninitialised value)
PR rtl-opt/69535
* combine.c (make_compound_operation): When looking through a
subreg, make sure to re-extend to the width of the outer mode.
From-SVN: r233032
Diffstat (limited to 'gcc/combine.c')
| -rw-r--r-- | gcc/combine.c | 24 |
1 files changed, 19 insertions, 5 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index 858552d..c307793 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -7887,11 +7887,25 @@ make_compound_operation (rtx x, enum rtx_code in_code) && GET_CODE (SUBREG_REG (XEXP (x, 0))) == LSHIFTRT && (i = exact_log2 (UINTVAL (XEXP (x, 1)) + 1)) >= 0) { - new_rtx = make_compound_operation (XEXP (SUBREG_REG (XEXP (x, 0)), 0), - next_code); - new_rtx = make_extraction (GET_MODE (SUBREG_REG (XEXP (x, 0))), new_rtx, 0, - XEXP (SUBREG_REG (XEXP (x, 0)), 1), i, 1, - 0, in_code == COMPARE); + rtx inner_x0 = SUBREG_REG (XEXP (x, 0)); + machine_mode inner_mode = GET_MODE (inner_x0); + new_rtx = make_compound_operation (XEXP (inner_x0, 0), next_code); + new_rtx = make_extraction (inner_mode, new_rtx, 0, + XEXP (inner_x0, 1), + i, 1, 0, in_code == COMPARE); + + if (new_rtx) + { + /* If we narrowed the mode when dropping the subreg, then + we must zero-extend to keep the semantics of the AND. */ + if (GET_MODE_SIZE (inner_mode) >= GET_MODE_SIZE (mode)) + ; + else if (SCALAR_INT_MODE_P (inner_mode)) + new_rtx = simplify_gen_unary (ZERO_EXTEND, mode, + new_rtx, inner_mode); + else + new_rtx = NULL; + } /* If that didn't give anything, see if the AND simplifies on its own. */ |