ira_get_dup_out_num punted on operands that are matched to
earlyclobber outputs:
/* It is better ignore an alternative with early clobber. */
else if (*str == '&')
goto fail;
But I'm not sure why this is the right thing to do. At this stage
we've established that *all* alternatives of interest require the
input to match the output, so
(a) the earlyclobber can only affect other operands and
(b) not tying the registers is bound to introduce a move
The code was part of the initial commit and so isn't obviously
related to a specific testcase. Also, I can imagine LRA makes
a much better job of this situation than reload did. (Certainly
SVE uses matched earlyclobbers extensively and I haven't seen any
problems.)
In case this turns out to regress something important: the main
case that matters for SVE is the one in which all alternatives
are earlyclobber.
2019-06-21 Richard Sandiford <richard.sandif...@arm.com>
gcc/
* ira.c (ira_get_dup_out_num): Don't punt for earlyclobbers.
Use recog_data to test for an output operand.
Index: gcc/ira.c
===================================================================
--- gcc/ira.c 2019-06-21 14:34:13.239653892 +0100
+++ gcc/ira.c 2019-06-21 14:34:15.947631377 +0100
@@ -1999,26 +1999,8 @@ ira_get_dup_out_num (int op_num, alterna
}
if (original == -1)
goto fail;
- dup = -1;
- for (ignore_p = false, str = recog_data.constraints[original - '0'];
- *str != 0;
- str++)
- if (ignore_p)
- {
- if (*str == ',')
- ignore_p = false;
- }
- else if (*str == '#')
- ignore_p = true;
- else if (! ignore_p)
- {
- if (*str == '=')
- dup = original - '0';
- /* It is better ignore an alternative with early clobber. */
- else if (*str == '&')
- goto fail;
- }
- if (dup >= 0)
+ dup = original - '0';
+ if (recog_data.operand_type[dup] == OP_OUT)
return dup;
fail:
if (use_commut_op_p)
