Re: Fix PR middle-end/102764

[Eric Botcazou via Gcc-patches]

> 2021-10-20  Eric Botcazou  <ebotca...@adacore.com>
> 
>       PR middle-end/102764
>       * cfgexpand.c (expand_gimple_basic_block): Disregard a final debug
>       statement to reset the current location for the outgoing edges.

This apparently breaks -fcompare-debug with -m32 so I have made it more robust 
by means of the attached fixlet.

Bootstrapped/regtested on x86-64/Linux, applied on the mainline as obvious.


        PR middle-end/102764
        * cfgexpand.c (expand_gimple_basic_block): Robustify latest change.

-- 
Eric Botcazou
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index 8b067f9d848..01d0cdc548a 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -5756,6 +5756,7 @@ expand_gimple_basic_block (basic_block bb, bool disable_tail_calls)
   rtx_insn *last;
   edge e;
   edge_iterator ei;
+  bool nondebug_stmt_seen = false;
 
   if (dump_file)
     fprintf (dump_file, "\n;; Generating RTL for gimple basic block %d\n",
@@ -5836,6 +5837,8 @@ expand_gimple_basic_block (basic_block bb, bool disable_tail_calls)
       basic_block new_bb;
 
       stmt = gsi_stmt (gsi);
+      if (!is_gimple_debug (stmt))
+	nondebug_stmt_seen = true;
 
       /* If this statement is a non-debug one, and we generate debug
 	 insns, then this one might be the last real use of a TERed
@@ -6090,7 +6093,7 @@ expand_gimple_basic_block (basic_block bb, bool disable_tail_calls)
   /* Expand implicit goto and convert goto_locus.  */
   FOR_EACH_EDGE (e, ei, bb->succs)
     {
-      if (e->goto_locus != UNKNOWN_LOCATION || !stmt || is_gimple_debug (stmt))
+      if (e->goto_locus != UNKNOWN_LOCATION || !nondebug_stmt_seen)
 	set_curr_insn_location (e->goto_locus);
       if ((e->flags & EDGE_FALLTHRU) && e->dest != bb->next_bb)
 	{