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flow.c (merge_blocks_nomove): Rewrite to properly handle two blocks that vanish entirely during merging.

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* flow.c (merge_blocks_nomove): Rewrite to properly handle two
        blocks that vanish entirely during merging.

From-SVN: r26339
This commit is contained in:
Richard Henderson 1999-04-10 14:06:47 -07:00 • committed by Richard Henderson
parent 6a4a5d954b
commit f5c14c21eb
2 changed files with 55 additions and 50 deletions
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5
gcc/ChangeLog
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@ -1,3 +1,8 @@
Fri Apr 9 11:29:17 1999 Richard Henderson <rth@cygnus.com>
* flow.c (merge_blocks_nomove): Rewrite to properly handle two
blocks that vanish entirely during merging.
Sat Apr 10 20:09:55 EDT 1999 John Wehle (john@feith.com)
* i386.md (floatsisf2, floatdisf2, floatsidf2, floatdidf2,

100
gcc/flow.c
View file

@ -1846,39 +1846,58 @@ merge_blocks_nomove (a, b)
basic_block a, b;
{
edge e;
rtx insn;
int done = 0;
rtx b_head, b_end, a_end;
int b_empty = 0;
/* If there was a CODE_LABEL beginning B, delete it. */
b_head = b->head;
b_end = b->end;
if (GET_CODE (b_head) == CODE_LABEL)
{
/* Detect basic blocks with nothing but a label. This can happen
in particular at the end of a function. */
if (b_head == b_end)
b_empty = 1;
b_head = flow_delete_insn (b_head);
}
/* Delete the basic block note. */
if (GET_CODE (b_head) == NOTE
&& NOTE_LINE_NUMBER (b_head) == NOTE_INSN_BASIC_BLOCK)
{
if (b_head == b_end)
b_empty = 1;
b_head = flow_delete_insn (b_head);
}
/* If there was a jump out of A, delete it. */
if (GET_CODE (a->end) == JUMP_INSN)
a_end = a->end;
if (GET_CODE (a_end) == JUMP_INSN)
{
/* If the jump was the only insn in A, turn the jump into a deleted
note, since we may yet not be able to merge the blocks. */
if (a->end == a->head)
{
PUT_CODE (a->head, NOTE);
NOTE_LINE_NUMBER (a->head) = NOTE_INSN_DELETED;
NOTE_SOURCE_FILE (a->head) = 0;
}
else
{
rtx tmp = a->end;
rtx prev;
a->end = prev_nonnote_insn (tmp);
prev = prev_nonnote_insn (a_end);
if (!prev)
prev = a->head;
#ifdef HAVE_cc0
/* If this was a conditional jump, we need to also delete
the insn that set cc0. */
if (! simplejump_p (tmp) && condjump_p (tmp))
{
PUT_CODE (PREV_INSN (tmp), NOTE);
NOTE_LINE_NUMBER (PREV_INSN (tmp)) = NOTE_INSN_DELETED;
NOTE_SOURCE_FILE (PREV_INSN (tmp)) = 0;
}
#endif
/* If this was a conditional jump, we need to also delete
the insn that set cc0. */
if (prev && sets_cc0_p (prev))
{
rtx tmp = prev;
prev = prev_nonnote_insn (prev);
if (!prev)
prev = a->head;
flow_delete_insn (tmp);
}
#endif
/* Note that a->head != a->end, since we should have at least a
bb note plus the jump, so prev != insn. */
flow_delete_insn (a_end);
a_end = prev;
}
/* By definition, there should only be one successor of A, and that is
@ -1890,37 +1909,18 @@ merge_blocks_nomove (a, b)
e->src = a;
a->succ = b->succ;
/* If there was a CODE_LABEL beginning B, delete it. */
insn = b->head;
if (GET_CODE (insn) == CODE_LABEL)
{
/* Detect basic blocks with nothing but a label. This can happen
in particular at the end of a function. */
if (insn == b->end)
done = 1;
insn = flow_delete_insn (insn);
}
/* Delete the basic block note. */
if (GET_CODE (insn) == NOTE
&& NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK)
{
if (insn == b->end)
done = 1;
insn = flow_delete_insn (insn);
}
/* Reassociate the insns of B with A. */
if (!done)
if (!b_empty)
{
BLOCK_FOR_INSN (insn) = a;
while (insn != b->end)
BLOCK_FOR_INSN (b_head) = a;
while (b_head != b_end)
{
insn = NEXT_INSN (insn);
BLOCK_FOR_INSN (insn) = a;
b_head = NEXT_INSN (b_head);
BLOCK_FOR_INSN (b_head) = a;
}
a->end = insn;
a_end = b_head;
}
a->end = a_end;
/* Compact the basic block array. */
expunge_block (b);