Re: [patch] PR inline-asm/55934

[Steven Bosscher <stevenb dot gcc at gmail dot com>]

On Sat, Jan 19, 2013 at 1:15 AM, Vladimir Makarov wrote:
> On 13-01-17 6:45 PM, Steven Bosscher wrote:
>>
>> Hello Vlad,
>>
>> Attached is my attempt to fix PR55934, an error recovery issue in LRA
>> with incorrect constraints in an asm.
>>
>> I'm not 100% sure this is all correct (especially the LRA insn data
>> invalidating in lra-assigns.c) but it appears to fix the PR without
>> introducing test suite failures.
>
> The code is correct but call lra_invalidate_insn_data is not necessary as
> the same thing will be done in lra_update_insn_recog_data (if what
> lra_invalidate_insn_data does is not done yet) .

That is what I expected, too. My first attempts didn't have the
lra_invalidate_insn_data call.

But I think lra_update_insn_recog_data calls lra_invalidate_insn_data
for asms. lra_invalidate_insn_data is called if there is existing
recog data but the insn code has changed:

  if ((data = lra_insn_recog_data[uid]) != NULL
      && data->icode != INSN_CODE (insn))
    {
      invalidate_insn_data_regno_info (data, insn, get_insn_freq (insn));
      invalidate_insn_recog_data (uid);
      data = NULL;
    }

For an asm, INSN_CODE==-1, so "data->icode != INSN_CODE (insn)" is
always false, and lra_invalidate_insn_data is never called. The result
is an ICE:

pr55512-3.c:15:1: internal compiler error: in
lra_update_insn_recog_data, at lra.c:1263
lra.c:1263            lra_assert (nop == data->insn_static_data->n_operands);


>  So adding the additional
> call is harmless as the result will be the same.

Given my explanation above, do you think we should make
lra_update_insn_recog_data handle asms as a special case? E.g.:

Index: lra.c
===================================================================
--- lra.c       (revision 195104)
+++ lra.c       (working copy)
@@ -1239,7 +1239,8 @@ lra_update_insn_recog_data (rtx insn)

   check_and_expand_insn_recog_data (uid);
   if ((data = lra_insn_recog_data[uid]) != NULL
-      && data->icode != INSN_CODE (insn))
+      && (data->icode != INSN_CODE (insn)
+         || asm_noperands (PATTERN (insn)) >= 0))
     {
       invalidate_insn_data_regno_info (data, insn, get_insn_freq (insn));
       invalidate_insn_recog_data (uid);


Or just keep the lra_invalidate_insn_data call?

Ciao!
Steven