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loop.c (check_dbra_loop): Update JUMP_LABEL field of jump insn when loop reversed.

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* loop.c (check_dbra_loop): Update JUMP_LABEL field of jump insn
	when loop reversed.
	* unroll.c (precondition_loop_p): Return loop_initial_value
	for initial_value instead of loop_iteration_var.

From-SVN: r23881
This commit is contained in:
Michael Hayes 1998-11-25 20:51:09 +00:00 committed by Michael Hayes
parent 959e0a7606
commit a70603680e
3 changed files with 25 additions and 20 deletions
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8
gcc/ChangeLog
View File

@ -1,3 +1,11 @@
Thu Nov 26 17:49:29 1998 Michael Hayes <m.hayes@elec.canterbury.ac.nz>
* loop.c (check_dbra_loop): Update JUMP_LABEL field of jump insn
when loop reversed.
* unroll.c (precondition_loop_p): Return loop_initial_value
for initial_value instead of loop_iteration_var.
Thu Nov 26 17:15:38 1998 Michael Hayes <m.hayes@elec.canterbury.ac.nz>
* config/c4x/c4x.md: Fix minor formatting problems. Update docs.

14
gcc/loop.c
View File

@ -7107,16 +7107,18 @@ check_dbra_loop (loop_end, insn_count, loop_start)
end_sequence ();
emit_jump_insn_before (tem, loop_end);
for (tem = PREV_INSN (loop_end);
tem && GET_CODE (tem) != JUMP_INSN;
tem = PREV_INSN (tem))
;
if (tem)
JUMP_LABEL (tem) = XEXP (jump_label, 0);
if (nonneg)
{
for (tem = PREV_INSN (loop_end);
tem && GET_CODE (tem) != JUMP_INSN;
tem = PREV_INSN (tem))
;
if (tem)
{
JUMP_LABEL (tem) = XEXP (jump_label, 0);
/* Increment of LABEL_NUSES done above. */
/* Register is now always nonnegative,
so add REG_NONNEG note to the branch. */

23
gcc/unroll.c
View File

@ -1410,19 +1410,6 @@ precondition_loop_p (initial_value, final_value, increment, loop_start)
return 0;
}
/* Now set initial_value to be the iteration_var, since that may be a
simpler expression, and is guaranteed to be correct if all of the
above tests succeed.
We can not use the initial_value as calculated, because it will be
one too small for loops of the form "while (i-- > 0)". We can not
emit code before the loop_skip_over insns to fix this problem as this
will then give a number one too large for loops of the form
"while (--i > 0)".
Note that all loops that reach here are entered at the top, because
this function is not called if the loop starts with a jump. */
/* Fail if loop_iteration_var is not live before loop_start, since we need
to test its value in the preconditioning code. */
@ -1435,7 +1422,15 @@ precondition_loop_p (initial_value, final_value, increment, loop_start)
return 0;
}
*initial_value = loop_iteration_var;
/* ??? Note that if iteration_info is modifed to allow GIV iterators
such as "while (i-- > 0)", the initial value will be one too small.
In this case, loop_iteration_var could be used to determine
the correct initial value, provided the loop has not been reversed.
Also note that the absolute values of initial_value and
final_value are unimportant as only their difference is used for
calculating the number of loop iterations. */
*initial_value = loop_initial_value;
*increment = loop_increment;
*final_value = loop_final_value;