I have a patch which makes use of the renamer more often, and this
exposed a bug with earlyclobber operands. The code that does the
terminate_write step has the following comment:
/* Step 5: Close open chains that overlap writes. Similar to
step 2, we hide in-out operands, since we do not want to
close these chains. We also hide earlyclobber operands,
since we've opened chains for them in step 1, and earlier
chains they would overlap with must have been closed at
the previous insn at the latest, as such operands cannot
possibly overlap with any input operands. */
That's all right as far as it goes, but the problem is that this means
there isn't a terminate_write step for earlyclobbers.
The following seems like the simplest possible fix. It was bootstrapped
and tested with -frename-registers enabled at -O1 on x86_64-linux. Ok?
(Incidentally there are some avx tests that fail if they are renamed,
apparently because the scan-assembler doesn't allow register numbers
like %zmm10. avx512bw-vptestmb-1.c is one of those).
Bernd
* regrename.c (record_out_operands): Terminate earlyclobbered
operands here.
Index: gcc/regrename.c
===================================================================
--- gcc/regrename.c (revision 229049)
+++ gcc/regrename.c (working copy)
@@ -1513,6 +1525,8 @@ record_out_operands (rtx_insn *insn, boo
cur_operand = insn_info->op_info + i;
prev_open = open_chains;
+ if (earlyclobber)
+ scan_rtx (insn, loc, cl, terminate_write, OP_OUT);
scan_rtx (insn, loc, cl, mark_write, OP_OUT);
/* ??? Many targets have output constraints on the SET_DEST
