diff options
| author | Richard Kenner <kenner@vlsi1.ultra.nyu.edu> | 2001-02-06 12:39:15 +0000 |
|---|---|---|
| committer | Richard Kenner <kenner@gcc.gnu.org> | 2001-02-06 07:39:15 -0500 |
| commit | d14057222fec681710cd1b1ac1d47478c0466bfb (patch) | |
| tree | ef948bedc788321fdca09d6b2f508f386ee213d9 /gcc/combine.c | |
| parent | a87b4257946d4453f250585aa22adc4f70db1165 (diff) | |
| download | gcc-d14057222fec681710cd1b1ac1d47478c0466bfb.zip gcc-d14057222fec681710cd1b1ac1d47478c0466bfb.tar.gz gcc-d14057222fec681710cd1b1ac1d47478c0466bfb.tar.bz2 | |
combine.c (nonzero_bits, case PLUS): If pointers extend unsigned and this is the sum of a pointer and a constant...
* combine.c (nonzero_bits, case PLUS): If pointers extend unsigned
and this is the sum of a pointer and a constant, we know the result
did not overflow.
(num_sign_bit_copies, case PLUS): Likewise.
* explow.c (convert_memory_address): Remove opposite SUBREG.
* function.c (instantiate_new_reg): New function (from common code).
(instantiate_virtual_regs_1): Call it.
For PLUS, handle if (plus (subreg (virt-reg) (const_int))
if pointers sign- or zero-extend.
* simplify-rtx.c (simplify_unary_operation, case ZERO_EXTEND):
If pointers extend unsigned, use inside of SUBREG.
(simplify_unary_operation, case SIGN_EXTEND): Likewise, if sign extend.
From-SVN: r39489
Diffstat (limited to 'gcc/combine.c')
| -rw-r--r-- | gcc/combine.c | 25 |
1 files changed, 24 insertions, 1 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index 74b02b5..662f05f 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -8308,6 +8308,16 @@ nonzero_bits (x, mode) if (result_low > 0) nonzero &= ~(((HOST_WIDE_INT) 1 << result_low) - 1); + +#ifdef POINTERS_EXTEND_UNSIGNED + /* If pointers extend unsigned and this is an addition or subtraction + to a pointer in Pmode, all the bits above ptr_mode are known to be + zero. */ + if (POINTERS_EXTEND_UNSIGNED && GET_MODE (x) == Pmode + && (code == PLUS || code == MINUS) + && GET_CODE (XEXP (x, 0)) == REG && REG_POINTER (XEXP (x, 0))) + nonzero &= GET_MODE_MASK (ptr_mode); +#endif } break; @@ -8646,7 +8656,20 @@ num_sign_bit_copies (x, mode) num0 = num_sign_bit_copies (XEXP (x, 0), mode); num1 = num_sign_bit_copies (XEXP (x, 1), mode); - return MAX (1, MIN (num0, num1) - 1); + result = MAX (1, MIN (num0, num1) - 1); + +#ifdef POINTERS_EXTEND_UNSIGNED + /* If pointers extend signed and this is an addition or subtraction + to a pointer in Pmode, all the bits above ptr_mode are known to be + sign bit copies. */ + if (! POINTERS_EXTEND_UNSIGNED && GET_MODE (x) == Pmode + && (code == PLUS || code == MINUS) + && GET_CODE (XEXP (x, 0)) == REG && REG_POINTER (XEXP (x, 0))) + result = MAX ((GET_MODE_BITSIZE (Pmode) + - GET_MODE_BITSIZE (ptr_mode) + 1), + result); +#endif + return result; case MULT: /* The number of bits of the product is the sum of the number of |