diff options
Diffstat (limited to 'gcc/combine.c')
| -rw-r--r-- | gcc/combine.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index 4782e1d..ed1ad45 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -7665,6 +7665,24 @@ make_extraction (machine_mode mode, rtx inner, HOST_WIDE_INT pos, if (new_rtx != 0) return gen_rtx_ASHIFT (mode, new_rtx, XEXP (inner, 1)); } + else if (GET_CODE (inner) == MULT + && CONST_INT_P (XEXP (inner, 1)) + && pos_rtx == 0 && pos == 0) + { + /* We're extracting the least significant bits of an rtx + (mult X (const_int 2^C)), where LEN > C. Extract the + least significant (LEN - C) bits of X, giving an rtx + whose mode is MODE, then multiply it by 2^C. */ + const HOST_WIDE_INT shift_amt = exact_log2 (INTVAL (XEXP (inner, 1))); + if (IN_RANGE (shift_amt, 1, len - 1)) + { + new_rtx = make_extraction (mode, XEXP (inner, 0), + 0, 0, len - shift_amt, + unsignedp, in_dest, in_compare); + if (new_rtx) + return gen_rtx_MULT (mode, new_rtx, XEXP (inner, 1)); + } + } else if (GET_CODE (inner) == TRUNCATE /* If trying or potentionally trying to extract bits outside of is_mode, don't look through |