Re: RFA: 4.9 gimple-fold PATCH for c++/62224

[Jason Merrill]

On 09/08/2014 03:51 PM, Jan Hubicka wrote:

You did not attach the patch.

Oops.



commit e57303b73d20fa75ffc535bbc219dc0f6472e431
Author: Jason Merrill <ja...@redhat.com>
Date:   Mon Sep 8 13:11:58 2014 -0400

    	PR c++/61214
    	PR c++/62224
    gcc/
    	* gimple-fold.c (can_refer_decl_in_current_unit_p): Don't allow
    	reference to a DECL_EXTERNAL COMDAT.
    gcc/cp/
    	* decl2.c (decl_needed_p): Revert virtual functions change.

diff --git a/gcc/cp/decl2.c b/gcc/cp/decl2.c
index 944b5ee..5549075 100644
--- a/gcc/cp/decl2.c
+++ b/gcc/cp/decl2.c
@@ -1940,11 +1940,6 @@ decl_needed_p (tree decl)
   if (flag_keep_inline_dllexport
       && lookup_attribute ("dllexport", DECL_ATTRIBUTES (decl)))
     return true;
-  /* Virtual functions might be needed for devirtualization.  */
-  if (flag_devirtualize
-      && TREE_CODE (decl) == FUNCTION_DECL
-      && DECL_VIRTUAL_P (decl))
-    return true;
   /* Otherwise, DECL does not need to be emitted -- yet.  A subsequent
      reference to DECL might cause it to be emitted later.  */
   return false;
diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
index c6aea65..2527d29 100644
--- a/gcc/gimple-fold.c
+++ b/gcc/gimple-fold.c
@@ -146,7 +146,8 @@ can_refer_decl_in_current_unit_p (tree decl, tree from_decl)
          The second is important when devirtualization happens during final
          compilation stage when making a new reference no longer makes callee
          to be compiled.  */
-      if (!node || !node->definition || node->global.inlined_to)
+      if (!node || !node->definition
+	  || DECL_EXTERNAL (decl) || node->global.inlined_to)
 	{
 	  gcc_checking_assert (!TREE_ASM_WRITTEN (decl));
 	  return false;
diff --git a/gcc/testsuite/g++.dg/ipa/devirt-39.C b/gcc/testsuite/g++.dg/ipa/devirt-39.C
index fbeea12..8cd734d 100644
--- a/gcc/testsuite/g++.dg/ipa/devirt-39.C
+++ b/gcc/testsuite/g++.dg/ipa/devirt-39.C
@@ -1,5 +1,5 @@
 // PR c++/61214
-/* { dg-options "-O2 -fdump-tree-optimized"  } */
+/* { dg-options "-O2"  } */
 
 struct Base
 {
@@ -24,5 +24,4 @@ int main()
   return 0;
 }
 
-/* { dg-final { scan-tree-dump-not "OBJ_TYPE_REF" "optimized"  } } */
-/* { dg-final { cleanup-tree-dump "optimized" } } */
+/* { dg-final { scan-assembler-not "_ZN3Foo5cloneEv" } } */
diff --git a/gcc/testsuite/g++.dg/ipa/devirt-40.C b/gcc/testsuite/g++.dg/ipa/devirt-40.C
new file mode 100644
index 0000000..9c3bdf5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ipa/devirt-40.C
@@ -0,0 +1,21 @@
+// PR c++/62224
+// { dg-options "-O2" }
+// For 4.9, we don't want to devirtualize f and thus create a reference to g.
+
+struct A
+{
+  virtual void f () = 0;
+};
+
+class B : A
+{
+  virtual void f () { g(); }
+  void g();
+};
+
+void h (A *a)
+{
+  a->f ();
+}
+
+// { dg-final { scan-assembler-not "_ZN1B1gEv" } }