I've tracked pr/88308 down to move_insn_for_shrink_wrap(). This function moves
an insn
from one BB to another by copying it and deleting the old one. Unfortunately
this does
the LABEL_NUSES count on labels referenced because deleting the old instruction
decrements
the count and nothing in this function is incrementing the count.
It just happens that on rs6000 with -m64, force_const_mem() gets called on the
address
and that sets LABEL_PRESERVE_P on the label which prevents it from being
deleted. For
whatever reason this doesn't happen in a -m32 compilation, and the label and
it's associated
jump table data are deleted. This later causes the ICE when the dwarf code
tries to look
at the label.
Segher and I came up with 3 possible solutions to this:
1) Don't let move_insn_for_shrink_wrap try to move insns with label_ref in them.
2) Call mark_jump_label() on the copied instruction to fix up the ref counts.
3) Make the function actually move the insn instead of copying/deleting it.
It seemed like option 2 was the best thing for stage 4 as it is not inhibiting
anything
and is just doing a fixup of the ref count.
OK for trunk after regtesting on ppc64be (32/64) and x86_64?
Thanks!
Aaron
2019-02-13 Aaron Sawdey <acsaw...@linux.ibm.com>
* shrink-wrap.c (move_insn_for_shrink_wrap): Fix LABEL_NUSES counts
on copied instruction.
Index: gcc/shrink-wrap.c
===================================================================
--- gcc/shrink-wrap.c (revision 268783)
+++ gcc/shrink-wrap.c (working copy)
@@ -414,7 +414,12 @@
dead_debug_insert_temp (debug, DF_REF_REGNO (def), insn,
DEBUG_TEMP_BEFORE_WITH_VALUE);
- emit_insn_after (PATTERN (insn), bb_note (bb));
+ rtx_insn *insn_copy = emit_insn_after (PATTERN (insn), bb_note (bb));
+ /* Update the LABEL_NUSES count on any referenced labels. The ideal
+ solution here would be to actually move the instruction instead
+ of copying/deleting it as this loses some notations on the
+ insn. */
+ mark_jump_label (PATTERN (insn), insn_copy, 0);
delete_insn (insn);
return true;
}
--
Aaron Sawdey, Ph.D. acsaw...@linux.vnet.ibm.com
050-2/C113 (507) 253-7520 home: 507/263-0782
IBM Linux Technology Center - PPC Toolchain
