diff options
| -rw-r--r-- | gcc/ChangeLog | 3 | ||||
| -rw-r--r-- | gcc/final.c | 55 |
2 files changed, 43 insertions, 15 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index b1e00d1..a1a00b1 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,5 +1,8 @@ 2000-05-20 Alexandre Oliva <aoliva@cygnus.com> + * final.c (split_double): Right shift of negative values is not + portable. + * ifcvt.c (if_convert): Scan and kill dead code. * emit-rtl.c (unshare_all_rtl): Store the copied rtx. diff --git a/gcc/final.c b/gcc/final.c index e24471c..2ab018b 100644 --- a/gcc/final.c +++ b/gcc/final.c @@ -3923,25 +3923,50 @@ split_double (value, first, second) /* In this case the CONST_INT holds both target words. Extract the bits from it into two word-sized pieces. Sign extend each half to HOST_WIDE_INT. */ - rtx low, high; - /* On machines where HOST_BITS_PER_WIDE_INT == BITS_PER_WORD - the shift below will cause a compiler warning, even though - this code won't be executed. So put the shift amounts in - variables to avoid the warning. */ - int rshift = HOST_BITS_PER_WIDE_INT - BITS_PER_WORD; - int lshift = HOST_BITS_PER_WIDE_INT - 2 * BITS_PER_WORD; - - low = GEN_INT ((INTVAL (value) << rshift) >> rshift); - high = GEN_INT ((INTVAL (value) << lshift) >> rshift); + unsigned HOST_WIDE_INT low, high; + unsigned HOST_WIDE_INT mask, sign_bit, sign_extend; + + /* Set sign_bit to the most significant bit of a word. */ + sign_bit = 1; + sign_bit <<= BITS_PER_WORD - 1; + + /* Set mask so that all bits of the word are set. We could + have used 1 << BITS_PER_WORD instead of basing the + calculation on sign_bit. However, on machines where + HOST_BITS_PER_WIDE_INT == BITS_PER_WORD, it could cause a + compiler warning, even though the code would never be + executed. */ + mask = sign_bit << 1; + mask--; + + /* Set sign_extend as any remaining bits. */ + sign_extend = ~mask; + + /* Pick the lower word and sign-extend it. */ + low = INTVAL (value); + low &= mask; + if (low & sign_bit) + low |= sign_extend; + + /* Pick the higher word, shifted to the least significant + bits, and sign-extend it. */ + high = INTVAL (value); + high >>= BITS_PER_WORD - 1; + high >>= 1; + high &= mask; + if (high & sign_bit) + high |= sign_extend; + + /* Store the words in the target machine order. */ if (WORDS_BIG_ENDIAN) { - *first = high; - *second = low; + *first = GEN_INT (high); + *second = GEN_INT (low); } else { - *first = low; - *second = high; + *first = GEN_INT (low); + *second = GEN_INT (high); } } else @@ -4026,7 +4051,7 @@ split_double (value, first, second) if ((HOST_FLOAT_FORMAT != TARGET_FLOAT_FORMAT || HOST_BITS_PER_WIDE_INT != BITS_PER_WORD) && ! flag_pretend_float) - abort (); + abort (); if ( #ifdef HOST_WORDS_BIG_ENDIAN |