diff options
Diffstat (limited to 'gcc/combine.c')
| -rw-r--r-- | gcc/combine.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index 3b298827413..ea12b130922 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -5968,6 +5968,21 @@ make_extraction (mode, inner, pos, pos_rtx, len, is_mode = GET_MODE (SUBREG_REG (inner)); inner = SUBREG_REG (inner); } + else if (GET_CODE (inner) == ASHIFT + && GET_CODE (XEXP (inner, 1)) == CONST_INT + && pos_rtx == 0 && pos == 0 + && len > INTVAL (XEXP (inner, 1))) + { + /* We're extracting the least significant bits of an rtx + (ashift X (const_int C)), where LEN > C. Extract the + least significant (LEN - C) bits of X, giving an rtx + whose mode is MODE, then shift it left C times. */ + new = make_extraction (mode, XEXP (inner, 0), + 0, 0, len - INTVAL (XEXP (inner, 1)), + unsignedp, in_dest, in_compare); + if (new != 0) + return gen_rtx_ASHIFT (mode, new, XEXP (inner, 1)); + } inner_mode = GET_MODE (inner); |