diff options
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. */ |