[PATCH] tree-optimization/106781 - adjust cgraph lhs removal

[Richard Biener <rguenther@suse.de>]

The following matches up the cgraph code removing LHS of a noreturn
call with what fixup_noreturn_call does which gets along without
inserting a definition, fixing the ICE resulting from having no
place to actually insert that new def.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

	PR tree-optimization/106781
	* cgraph.cc (cgraph_edge::redirect_call_stmt_to_callee): Copy
	LHS removal from fixup_noreturn_call.

	* gcc.dg/pr106781.c: New testcase.
---
 gcc/cgraph.cc                   | 14 ++++++--------
 gcc/testsuite/gcc.dg/pr106781.c | 18 ++++++++++++++++++
 2 files changed, 24 insertions(+), 8 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/pr106781.c

diff --git a/gcc/cgraph.cc b/gcc/cgraph.cc
index 0417b059965..5851b2ffc6c 100644
--- a/gcc/cgraph.cc
+++ b/gcc/cgraph.cc
@@ -1411,7 +1411,6 @@ cgraph_edge::redirect_call_stmt_to_callee (cgraph_edge *e)
 {
   tree decl = gimple_call_fndecl (e->call_stmt);
   gcall *new_stmt;
-  gimple_stmt_iterator gsi;
 
   if (e->speculative)
     {
@@ -1572,18 +1571,17 @@ cgraph_edge::redirect_call_stmt_to_callee (cgraph_edge *e)
       && (VOID_TYPE_P (TREE_TYPE (gimple_call_fntype (new_stmt)))
 	  || should_remove_lhs_p (lhs)))
     {
+      gimple_call_set_lhs (new_stmt, NULL_TREE);
+      /* We need to fix up the SSA name to avoid checking errors.  */
       if (TREE_CODE (lhs) == SSA_NAME)
 	{
 	  tree var = create_tmp_reg_fn (DECL_STRUCT_FUNCTION (e->caller->decl),
 					TREE_TYPE (lhs), NULL);
-	  var = get_or_create_ssa_default_def
-		  (DECL_STRUCT_FUNCTION (e->caller->decl), var);
-	  gimple *set_stmt = gimple_build_assign (lhs, var);
-	  gsi = gsi_for_stmt (new_stmt);
-	  gsi_insert_before_without_update (&gsi, set_stmt, GSI_SAME_STMT);
-	  update_stmt_fn (DECL_STRUCT_FUNCTION (e->caller->decl), set_stmt);
+	  SET_SSA_NAME_VAR_OR_IDENTIFIER (lhs, var);
+	  SSA_NAME_DEF_STMT (lhs) = gimple_build_nop ();
+	  set_ssa_default_def (DECL_STRUCT_FUNCTION (e->caller->decl),
+			       var, lhs);
 	}
-      gimple_call_set_lhs (new_stmt, NULL_TREE);
       update_stmt_fn (DECL_STRUCT_FUNCTION (e->caller->decl), new_stmt);
     }
 
diff --git a/gcc/testsuite/gcc.dg/pr106781.c b/gcc/testsuite/gcc.dg/pr106781.c
new file mode 100644
index 00000000000..339c28c41df
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr106781.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -Wno-div-by-zero" } */
+
+int n;
+
+__attribute__ ((noinline, returns_twice)) static int
+bar (int)
+{
+  n /= 0;
+
+  return n;
+}
+
+int
+foo (int x)
+{
+  return bar (x);
+}
-- 
2.35.3