diff options
Diffstat (limited to 'gcc/simplify-rtx.c')
| -rw-r--r-- | gcc/simplify-rtx.c | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c index 17568baa8b0..c4fc42aebcf 100644 --- a/gcc/simplify-rtx.c +++ b/gcc/simplify-rtx.c @@ -714,6 +714,34 @@ simplify_truncation (machine_mode mode, rtx op, return simplify_gen_binary (ASHIFT, mode, XEXP (XEXP (op, 0), 0), XEXP (op, 1)); + /* Likewise (truncate:QI (and:SI (lshiftrt:SI (x:SI) C) C2)) into + (and:QI (lshiftrt:QI (truncate:QI (x:SI)) C) C2) for suitable C + and C2. */ + if (GET_CODE (op) == AND + && (GET_CODE (XEXP (op, 0)) == LSHIFTRT + || GET_CODE (XEXP (op, 0)) == ASHIFTRT) + && CONST_INT_P (XEXP (XEXP (op, 0), 1)) + && CONST_INT_P (XEXP (op, 1))) + { + rtx op0 = (XEXP (XEXP (op, 0), 0)); + rtx shift_op = XEXP (XEXP (op, 0), 1); + rtx mask_op = XEXP (op, 1); + unsigned HOST_WIDE_INT shift = UINTVAL (shift_op); + unsigned HOST_WIDE_INT mask = UINTVAL (mask_op); + + if (shift < precision + /* If doing this transform works for an X with all bits set, + it works for any X. */ + && ((GET_MODE_MASK (mode) >> shift) & mask) + == ((GET_MODE_MASK (op_mode) >> shift) & mask) + && (op0 = simplify_gen_unary (TRUNCATE, mode, op0, op_mode)) + && (op0 = simplify_gen_binary (LSHIFTRT, mode, op0, shift_op))) + { + mask_op = GEN_INT (trunc_int_for_mode (mask, mode)); + return simplify_gen_binary (AND, mode, op0, mask_op); + } + } + /* Recognize a word extraction from a multi-word subreg. */ if ((GET_CODE (op) == LSHIFTRT || GET_CODE (op) == ASHIFTRT) |