From: Richard Biener <rguenther@suse.de>
Date: Thu, 19 Nov 2020 09:43:35 +0000 (+0100)
Subject: tree-optimization/97901 - ICE propagating out LC PHIs
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=ec383f0bdb4077b744d493d02afff5f13f33029e;p=gcc.git

tree-optimization/97901 - ICE propagating out LC PHIs

We need to fold the stmt to canonicalize MEM_REFs which means
we're back to using replace_uses_by.  Which means we need dominators
to not require a CFG cleanup upthread.

2020-11-19  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/97901
	* tree-ssa-propagate.c (clean_up_loop_closed_phi): Compute
	dominators and use replace_uses_by.

	* gcc.dg/torture/pr97901.c: New testcase.
---

diff --git a/gcc/testsuite/gcc.dg/torture/pr97901.c b/gcc/testsuite/gcc.dg/torture/pr97901.c
new file mode 100644
index 00000000000..a6a89ef1e27
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr97901.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+
+int a[1], b, *c, *d;
+
+int main() {
+L:
+  d = c;
+  for (b = 0; b < 2; b++)
+    d = &a[0];
+  if (c)
+    goto L;
+  if (*d)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/tree-ssa-propagate.c b/gcc/tree-ssa-propagate.c
index 354057b48bf..bc656ff76b1 100644
--- a/gcc/tree-ssa-propagate.c
+++ b/gcc/tree-ssa-propagate.c
@@ -1569,6 +1569,10 @@ clean_up_loop_closed_phi (function *fun)
   if (!loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS))
     return 0;
 
+  /* replace_uses_by might purge dead EH edges and we want it to also
+     remove dominated blocks.  */
+  calculate_dominance_info  (CDI_DOMINATORS);
+
   /* Walk over loop in function.  */
   FOR_EACH_LOOP_FN (fun, loop, 0)
     {
@@ -1595,23 +1599,7 @@ clean_up_loop_closed_phi (function *fun)
 		      fprintf (dump_file, "'\n");
 		    }
 
-		  use_operand_p use_p;
-		  imm_use_iterator iter;
-		  gimple *use_stmt;
-		  FOR_EACH_IMM_USE_STMT (use_stmt, iter, lhs)
-		    {
-		      FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
-			replace_exp (use_p, rhs);
-		      update_stmt (use_stmt);
-
-		      /* Update the invariant flag for ADDR_EXPR if replacing
-			 a variable index with a constant.  */
-		      if (gimple_assign_single_p (use_stmt)
-			  && TREE_CODE (gimple_assign_rhs1 (use_stmt))
-			       == ADDR_EXPR)
-			recompute_tree_invariant_for_addr_expr (
-			  gimple_assign_rhs1 (use_stmt));
-		    }
+		  replace_uses_by (lhs, rhs);
 		  remove_phi_node (&gsi, true);
 		}
 	      else