OpenE2K/gcc
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

final.c (split_double): Right shift of negative values is not portable.

Browse Source 
* final.c (split_double): Right shift of negative values is not
portable.

From-SVN: r34061
This commit is contained in:
Alexandre Oliva 2000-05-20 23:01:00 +00:00 committed by Alexandre Oliva
parent 6b48deee6e
commit 7f251deef0
2 changed files with 42 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
gcc/ChangeLog
View File

@ -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.

53
gcc/final.c
View File

@ -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;
unsigned HOST_WIDE_INT low, high;
unsigned HOST_WIDE_INT mask, sign_bit, sign_extend;
low = GEN_INT ((INTVAL (value) << rshift) >> rshift);
high = GEN_INT ((INTVAL (value) << lshift) >> rshift);
/* 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