Re: [Patch] Improving jump-thread pass for PR 54742

[Sebastian Pop]

Sebastian Pop wrote:
> a fail I have not seen in the past:
> 
> FAIL: gcc.c-torture/compile/pr27571.c   -Os  (internal compiler error)
> 
> I am still investigating why this fails: as far as I can see for now this is
> because in copying the FSM path we create an internal loop that is then
> discovered by the loop verifier as a natural loop and is not yet in the 
> existing
> loop sturctures.  I will try to fix this in duplicate_seme by invalidating the
> loop structure after we code generated all the FSM paths.  I will submit an
> updated patch when it passes regtest.

We need at least this patch to fix the fail:

@@ -2518,6 +2518,7 @@ thread_through_all_blocks (bool may_peel_loop_headers)
      if (duplicate_seme_region (entry, exit, region, len - 1, NULL))           
                                                                                
                                                                 
        {                                                             
          /* We do not update dominance info.  */
          free_dominance_info (CDI_DOMINATORS);
          bitmap_set_bit (threaded_blocks, entry->src->index);
+         retval = true;
        }

And this will trigger in the end of the code gen function:

 if (retval)
    loops_state_set (LOOPS_NEED_FIXUP);

That will fix the loop structures.  I'm testing this patch on top of the one I
have just sent out.

Sebastian