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| author | Richard Kenner <kenner@gcc.gnu.org> | 1993-05-19 18:09:24 -0400 |
|---|---|---|
| committer | Richard Kenner <kenner@gcc.gnu.org> | 1993-05-19 18:09:24 -0400 |
| commit | 9afa3d548eb07d4d5b233b585501474a23625af5 (patch) | |
| tree | c9614a5dd500d45461b891936017ab1122dd710b /gcc | |
| parent | b310570af3762926756f56c4d22db577f95d1e5d (diff) | |
| download | gcc-9afa3d548eb07d4d5b233b585501474a23625af5.zip gcc-9afa3d548eb07d4d5b233b585501474a23625af5.tar.gz gcc-9afa3d548eb07d4d5b233b585501474a23625af5.tar.bz2 | |
(set_nonzero_bits_and_sign_copies...
(set_nonzero_bits_and_sign_copies, nonzero_bits): If we have a
positive constant that is negative in the mode it is being used in,
treat it as negative.
From-SVN: r4506
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/combine.c | 59 |
1 files changed, 57 insertions, 2 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index e53d1a6..ca1567c 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -692,8 +692,31 @@ set_nonzero_bits_and_sign_copies (x, set) > GET_MODE_SIZE (GET_MODE (SUBREG_REG (SET_DEST (set))))) && SUBREG_REG (SET_DEST (set)) == x)) { + rtx src = SET_SRC (set); + +#ifdef SHORT_IMMEDIATES_SIGN_EXTEND + /* If X is narrower than a word and SRC is a non-negative + constant that would appear negative in the mode of X, + sign-extend it for use in reg_nonzero_bits because some + machines (maybe most) will actually do the sign-extension + and this is the conservative approach. + + ??? For 2.5, try to tighten up the MD files in this regard + instead of this kludge. */ + + if (GET_MODE_BITSIZE (GET_MODE (x)) < BITS_PER_WORD + && GET_CODE (src) == CONST_INT + && INTVAL (src) > 0 + && 0 != (INTVAL (src) + & ((HOST_WIDE_INT) 1 + << GET_MODE_BITSIZE (GET_MODE (x))))) + src = GEN_INT (INTVAL (src) + | ((HOST_WIDE_INT) (-1) + << GET_MODE_BITSIZE (GET_MODE (x)))); +#endif + reg_nonzero_bits[REGNO (x)] - |= nonzero_bits (SET_SRC (set), nonzero_bits_mode); + |= nonzero_bits (src, nonzero_bits_mode); num = num_sign_bit_copies (SET_SRC (set), GET_MODE (x)); if (reg_sign_bit_copies[REGNO (x)] == 0 || reg_sign_bit_copies[REGNO (x)] > num) @@ -6222,14 +6245,46 @@ nonzero_bits (x, mode) return reg_last_set_nonzero_bits[REGNO (x)]; tem = get_last_value (x); + if (tem) - return nonzero_bits (tem, mode); + { +#ifdef SHORT_IMMEDIATES_SIGN_EXTEND + /* If X is narrower than MODE and TEM is a non-negative + constant that would appear negative in the mode of X, + sign-extend it for use in reg_nonzero_bits because some + machines (maybe most) will actually do the sign-extension + and this is the conservative approach. + + ??? For 2.5, try to tighten up the MD files in this regard + instead of this kludge. */ + + if (GET_MODE_BITSIZE (GET_MODE (x)) < mode_width + && GET_CODE (tem) == CONST_INT + && INTVAL (tem) > 0 + && 0 != (INTVAL (tem) + & ((HOST_WIDE_INT) 1 + << GET_MODE_BITSIZE (GET_MODE (x))))) + tem = GEN_INT (INTVAL (tem) + | ((HOST_WIDE_INT) (-1) + << GET_MODE_BITSIZE (GET_MODE (x)))); +#endif + return nonzero_bits (tem, mode); + } else if (nonzero_sign_valid && reg_nonzero_bits[REGNO (x)]) return reg_nonzero_bits[REGNO (x)] & nonzero; else return nonzero; case CONST_INT: +#ifdef SHORT_IMMEDIATES_SIGN_EXTEND + /* If X is negative in MODE, sign-extend the value. */ + if (INTVAL (x) > 0 + && 0 != (INTVAL (x) + & ((HOST_WIDE_INT) 1 << GET_MODE_BITSIZE (GET_MODE (x))))) + return (INTVAL (x) + | ((HOST_WIDE_INT) (-1) << GET_MODE_BITSIZE (GET_MODE (x)))); +#endif + return INTVAL (x); #ifdef BYTE_LOADS_ZERO_EXTEND |