re PR middle-end/24295 (Xorg broken, #pragma weak foo = bar no longer causes bar to be referenced)

gcc/ChangeLog:
PR middle-end/24295
* cgraphunit.c (cgraph_varpool_remove_unreferenced_decls): Mark
alias targets.
* varasm.c (find_decl_and_mark_needed): After cgraph global info
is ready, stop marking functions, but still mark variables.
gcc/testsuite/ChangeLog:
PR middle-end/24295
* g++.old-deja/g++.abi/vtable2.C: Do not introduce external
declarations with the same names as thunks' alias targets, use
aliases instead.
* gcc.dg/attr-alias-3.c: New test.
* gcc.dg/weak/weak-14.c, gcc.dg/weak/weak-14a.c: New test.

From-SVN: r105688

gcc/ChangeLog

+2005-10-20  Alexandre Oliva  <aoliva@redhat.com>
+
+	PR middle-end/24295
+	* cgraphunit.c (cgraph_varpool_remove_unreferenced_decls): Mark
+	alias targets.
+	* varasm.c (find_decl_and_mark_needed): After cgraph global info
+	is ready, stop marking functions, but still mark variables.
+
 2005-10-20  Richard Guenther  <rguenther@suse.de>
 
 	PR c++/24439

gcc/cgraphunit.c

@@ -322,6 +322,8 @@ cgraph_varpool_remove_unreferenced_decls (void)
 
       node = next;
     }
+  /* Make sure we mark alias targets as used targets.  */
+  finish_aliases_1 ();
   cgraph_varpool_analyze_pending_decls ();
 }
 

gcc/testsuite/ChangeLog

+2005-10-20  Alexandre Oliva  <aoliva@redhat.com>
+
+	PR middle-end/24295
+	* g++.old-deja/g++.abi/vtable2.C: Do not introduce external
+	declarations with the same names as thunks' alias targets, use
+	aliases instead.
+	* gcc.dg/attr-alias-3.c: New test.
+	* gcc.dg/weak/weak-14.c, gcc.dg/weak/weak-14a.c: New test.
+
 2005-10-20  Mark Mitchell  <mark@codesourcery.com>
 
 	PR c++/22618

gcc/testsuite/g++.old-deja/g++.abi/vtable2.C

@@ -124,8 +124,8 @@ void S4::s1 ()
 // These are tricks to allow us to get raw function pointers for
 // member functions.
 extern "C" {
-void _ZN2S32s3Ev ();
-void _ZN2S42s1Ev ();
+  void S3_s3 () __attribute__((__alias__ ("_ZN2S32s3Ev")));
+  void S4_s1 () __attribute__((__alias__ ("_ZN2S42s1Ev")));
 }
 
 // IA-64 uses function descriptors not function pointers in its vtables.
@@ -169,10 +169,10 @@ int main ()
   INC_VDATA (vtbl, 1);
   // Skip the RTTI entry.
   INC_VDATA (vtbl, 1);
-  if (! CMP_VPTR (vtbl, &_ZN2S32s3Ev))
+  if (! CMP_VPTR (vtbl, &S3_s3))
     return 5;
   INC_VPTR (vtbl);
-  if (! CMP_VPTR (vtbl, &_ZN2S42s1Ev))
+  if (! CMP_VPTR (vtbl, &S4_s1))
     return 6;
   INC_VPTR (vtbl);
   // The S1 vbase offset.

gcc/testsuite/gcc.dg/attr-alias-3.c

+// { dg-do link }
+// { dg-require-alias "" }
+// { dg-options "-O2 -fno-common" }
+
+// Copyright 2005 Free Software Foundation, Inc.
+// Contributed by Alexandre Oliva <aoliva@redhat.com>
+
+// PR middle-end/24295
+
+// The unit-at-a-time call graph code used to fail to emit variables
+// without external linkage that were only used indirectly, through
+// aliases.  Although the PR above is about #pragma weak-introduced
+// aliases, the underlying machinery is the same.
+
+#ifndef ATTRIBUTE_USED
+# define ATTRIBUTE_USED __attribute__((used))
+#endif
+
+static int lv1;
+extern int Av1a __attribute__((alias ("lv1")));
+int *pv1a = &Av1a;
+
+static int lv2;
+extern int Av2a __attribute__((alias ("lv2")));
+int *pv2a = &lv2;
+
+static int lv3;
+extern int Av3a __attribute__((alias ("lv3")));
+static int *pv3a ATTRIBUTE_USED = &Av3a;
+
+static int lv4;
+extern int Av4a __attribute__((alias ("lv4")));
+static int *pv4a = &Av4a;
+
+typedef void ftype(void);
+
+static void lf1(void) {}
+extern ftype Af1a __attribute__((alias ("lf1")));
+ftype *pf1a = &Af1a;
+
+static void lf2(void) {}
+extern ftype Af2a __attribute__((alias ("lf2")));
+ftype *pf2a = &Af2a;
+
+static void lf3(void) {}
+extern ftype Af3a __attribute__((alias ("lf3")));
+static ftype *pf3a ATTRIBUTE_USED = &Af3a;
+
+static void lf4(void) {}
+extern ftype Af4a __attribute__((alias ("lf4")));
+static ftype *pf4a = &Af4a;
+
+main() {
+  asm volatile ("" : : "m" (pv4a), "m" (pf4a));
+}

gcc/testsuite/gcc.dg/weak/weak-14.c

+// { dg-do run }
+// { dg-require-weak "" }
+// { dg-options "-O2 -fno-common" }
+
+// Copyright 2005 Free Software Foundation, Inc.
+// Contributed by Alexandre Oliva <aoliva@redhat.com>
+
+// PR middle-end/24295
+
+// The unit-at-a-time call graph code used to fail to emit variables
+// without external linkage that were only used indirectly, through
+// aliases.  We might then get linker failures because the static
+// variable was not defined, or run-time errors because the weak alias
+// ended up pointing somewhere random.
+
+#include <stdlib.h>
+
+static unsigned long lv1 = 0xdeadbeefUL;
+#pragma weak Av1a = lv1
+extern unsigned long Av1a;
+
+static unsigned long lf1(void) { return 0x510bea7UL; }
+#pragma weak Af1a = lf1
+extern unsigned long Af1a(void);
+
+int main (void) {
+  if (! &Av1a
+      || ! &Af1a
+      || Av1a != 0xdeadbeefUL
+      || Af1a() != 0x510bea7UL)
+    abort ();
+  exit (0);
+}

gcc/varasm.c

@@ -4560,27 +4560,28 @@ find_decl_and_mark_needed (tree decl, tree target)
   struct cgraph_node *fnode = NULL;
   struct cgraph_varpool_node *vnode = NULL;
 
-  /* C++ thunk emitting code produces aliases late in the game.
-     Avoid confusing cgraph code in that case.  */
-  if (!cgraph_global_info_ready)
+  if (TREE_CODE (decl) == FUNCTION_DECL)
     {
-      if (TREE_CODE (decl) == FUNCTION_DECL)
-	{
-	  fnode = cgraph_node_for_asm (target);
-	  if (fnode == NULL)
-	    vnode = cgraph_varpool_node_for_asm (target);
-	}
-      else
-	{
-	  vnode = cgraph_varpool_node_for_asm (target);
-	  if (vnode == NULL)
-	    fnode = cgraph_node_for_asm (target);
-	}
+      fnode = cgraph_node_for_asm (target);
+      if (fnode == NULL)
+	vnode = cgraph_varpool_node_for_asm (target);
+    }
+  else
+    {
+      vnode = cgraph_varpool_node_for_asm (target);
+      if (vnode == NULL)
+	fnode = cgraph_node_for_asm (target);
     }
 
   if (fnode)
     {
-      cgraph_mark_needed_node (fnode);
+      /* We can't mark function nodes as used after cgraph global info
+	 is finished.  This wouldn't generally be necessary, but C++
+	 virtual table thunks are introduced late in the game and
+	 might seem like they need marking, although in fact they
+	 don't.  */
+      if (! cgraph_global_info_ready)
+	cgraph_mark_needed_node (fnode);
       return fnode->decl;
     }
   else if (vnode)