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simplify-rtx.c (simplify_subreg): Fix combining of paradoxical subregs.

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* simplify-rtx.c (simplify_subreg): Fix combining of
	paradoxical subregs.

From-SVN: r42868
This commit is contained in:
Jan Hubicka 2001-06-04 20:44:57 +02:00 committed by Jan Hubicka
parent 978f547fa2
commit 1ffb3f9ac1
2 changed files with 53 additions and 26 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
Mon Jun 4 20:44:25 CEST 2001 Jan Hubicka <jh@suse.cz>
* simplify-rtx.c (simplify_subreg): Fix combining of
paradoxical subregs.
Mon Jun 4 20:15:25 CEST 2001 Jan Hubicka <jh@suse.cz>
* rtlanal.c (rtx_unsable_p): ADDRESSOF is stable.

74
gcc/simplify-rtx.c
View File

@ -2297,41 +2297,63 @@ simplify_subreg (outermode, op, innermode, byte)
if (GET_CODE (op) == SUBREG)
{
enum machine_mode innermostmode = GET_MODE (SUBREG_REG (op));
unsigned int final_offset = byte + SUBREG_BYTE (op);
int final_offset = byte + SUBREG_BYTE (op);
rtx new;
if (outermode == innermostmode
&& byte == 0 && SUBREG_BYTE (op) == 0)
return SUBREG_REG (op);
if ((WORDS_BIG_ENDIAN || BYTES_BIG_ENDIAN)
&& GET_MODE_SIZE (innermode) > GET_MODE_SIZE (outermode)
&& GET_MODE_SIZE (innermode) > GET_MODE_SIZE (innermostmode))
/* The SUBREG_BYTE represents offset, as if the value were stored
in memory. Irritating exception is paradoxical subreg, where
we define SUBREG_BYTE to be 0. On big endian machines, this
value should be negative. For a moment, undo this exception. */
if (byte == 0 && GET_MODE_SIZE (innermode) < GET_MODE_SIZE (outermode))
{
/* Inner SUBREG is paradoxical, outer is not. On big endian
we have to special case this. */
if (SUBREG_BYTE (op))
abort(); /* Can a paradoxical subreg have nonzero offset? */
if (WORDS_BIG_ENDIAN && BYTES_BIG_ENDIAN)
final_offset = (byte - GET_MODE_SIZE (innermode)
+ GET_MODE_SIZE (innermostmode));
else if (WORDS_BIG_ENDIAN)
final_offset = ((final_offset % UNITS_PER_WORD)
+ ((byte - GET_MODE_SIZE (innermode)
+ GET_MODE_SIZE (innermostmode))
* UNITS_PER_WORD) / UNITS_PER_WORD);
else
final_offset = (((final_offset * UNITS_PER_WORD)
/ UNITS_PER_WORD)
+ ((byte - GET_MODE_SIZE (innermode)
+ GET_MODE_SIZE (innermostmode))
% UNITS_PER_WORD));
int difference = (GET_MODE_SIZE (innermode) - GET_MODE_SIZE (outermode));
if (WORDS_BIG_ENDIAN)
final_offset += (difference / UNITS_PER_WORD) * UNITS_PER_WORD;
if (BYTES_BIG_ENDIAN)
final_offset += difference % UNITS_PER_WORD;
}
if (SUBREG_BYTE (op) == 0
&& GET_MODE_SIZE (innermostmode) < GET_MODE_SIZE (innermode))
{
int difference = (GET_MODE_SIZE (innermostmode) - GET_MODE_SIZE (innermode));
if (WORDS_BIG_ENDIAN)
final_offset += (difference / UNITS_PER_WORD) * UNITS_PER_WORD;
if (BYTES_BIG_ENDIAN)
final_offset += difference % UNITS_PER_WORD;
}
/* See whether resulting subreg will be paradoxical. */
if (GET_MODE_SIZE (innermostmode) < GET_MODE_SIZE (outermode))
{
/* In nonparadoxical subregs we can't handle negative offsets. */
if (final_offset < 0)
return NULL_RTX;
/* Bail out in case resulting subreg would be incorrect. */
if (final_offset % GET_MODE_SIZE (outermode)
|| final_offset >= GET_MODE_SIZE (innermostmode))
return NULL;
}
else
{
int offset = 0;
int difference = (GET_MODE_SIZE (innermostmode) - GET_MODE_SIZE (outermode));
/* In paradoxical subreg, see if we are still looking on lower part.
If so, our SUBREG_BYTE will be 0. */
if (WORDS_BIG_ENDIAN)
offset += (difference / UNITS_PER_WORD) * UNITS_PER_WORD;
if (BYTES_BIG_ENDIAN)
offset += difference % UNITS_PER_WORD;
if (offset == final_offset)
final_offset = 0;
else
return NULL;
}
/* Bail out in case resulting subreg would be incorrect. */
if (final_offset % GET_MODE_SIZE (outermode)
|| final_offset >= GET_MODE_SIZE (innermostmode))
return NULL;
/* Recurse for futher possible simplifications. */
new = simplify_subreg (outermode, SUBREG_REG (op),
GET_MODE (SUBREG_REG (op)),