Another cprop trap_if fix, PR79125

[Bernd Schmidt]

This is essentially the same patch I sent for the previous instance of 
this problem, but this time applied to local_cprop_pass. Bootstrapped 
and tested on x86_64-linux, and it seems to fix the testcase with a ppc 
cross. Ok?

Bernd
	PR rtl-optimization/79125
	* cprop.c (local_cprop_pass): Handle cases where we make an
	unconditional trap.

	PR rtl-optimization/79125
	* gcc.dg/torture/pr79125.c: New test.

Index: gcc/cprop.c
===================================================================
--- gcc/cprop.c	(revision 244528)
+++ gcc/cprop.c	(working copy)
@@ -1248,6 +1248,8 @@ local_cprop_pass (void)
   bool changed = false;
   unsigned i;
 
+  auto_vec<rtx_insn *> uncond_traps;
+
   cselib_init (0);
   FOR_EACH_BB_FN (bb, cfun)
     {
@@ -1255,6 +1257,9 @@ local_cprop_pass (void)
 	{
 	  if (INSN_P (insn))
 	    {
+	      bool was_uncond_trap
+		= (GET_CODE (PATTERN (insn)) == TRAP_IF
+		   && XEXP (PATTERN (insn), 0) == const1_rtx);
 	      rtx note = find_reg_equal_equiv_note (insn);
 	      do
 		{
@@ -1273,6 +1278,13 @@ local_cprop_pass (void)
 			  break;
 			}
 		    }
+		  if (!was_uncond_trap
+		      && GET_CODE (PATTERN (insn)) == TRAP_IF
+		      && XEXP (PATTERN (insn), 0) == const1_rtx)
+		    {
+		      uncond_traps.safe_push (insn);
+		      break;
+		    }
 		  if (insn->deleted ())
 		    break;
 		}
@@ -1287,6 +1299,14 @@ local_cprop_pass (void)
 
   cselib_finish ();
 
+  while (!uncond_traps.is_empty ())
+    {
+      rtx_insn *insn = uncond_traps.pop ();
+      basic_block to_split = BLOCK_FOR_INSN (insn);
+      remove_edge (split_block (to_split, insn));
+      emit_barrier_after_bb (to_split);
+    }
+
   return changed;
 }
 
Index: gcc/testsuite/gcc.dg/torture/pr79125.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr79125.c	(nonexistent)
+++ gcc/testsuite/gcc.dg/torture/pr79125.c	(working copy)
@@ -0,0 +1,32 @@
+int za;
+
+void
+hl (void)
+{
+  short int o8 = 0;
+  short int m6 = 1;
+  short int *ni = &m6;
+
+  for (;;)
+    {
+      int af;
+      short int *fd = (short int *)&ni;
+
+      if (ni != 0)
+        {
+          if (m6 != 0)
+            *ni = 0;
+          else
+            za = 0;
+          af = (o8 * o8) || o8;
+          if (af == 0)
+            m6 /= 0; /* { dg-warning "division" } */
+          while (za != 0)
+            {
+            }
+        }
+      *fd = &o8; /* { dg-warning "without a cast" } */
+      for (af = 0; af < 2; ++af)
+        af = za;
+    }
+}