Re: A testcase anad a patch for the __gmon_start__ problem on PPC.

["H . J . Lu" <hjl at lucon dot org>]

On Tue, Oct 10, 2000 at 08:30:14PM -0700, H . J . Lu wrote:

> to weak undefined. That is the same thing as __gmon_start__ on PPC. We
> don't see the problem on x86 since WEAK_GMON_START is defined for x86.
> Those 2 changes have no impact on x86 as far as __gmon_start__ is
> concerned. If we want the binary compatibility, we need to put back
> the weak defined __gmon_start__ for all targets where WEAK_GMON_START
> is not defined before. One way to fix it is to provide a PPC initfini.c.
> 
> 
> H.J.
> ---
> 2000-10-10  H.J. Lu  <hjl@gnu.org>
> 
> 	* sysdeps/powerpc/initfini.c: New. For the binary compatibility.

My second thought, since only i386 defines WEAK_GMON_START before, it
seems that all but i386 are affected. Here is a new patch.


H.J.
-----
2000-10-10  H.J. Lu  <hjl@gnu.org>

	* sysdeps/generic/initfini-compat.c: New. For the binary
	compatibility.

	* sysdeps/powerpc/initfini.c: New.

--- /dev/null	Thu Aug 24 02:00:32 2000
+++ sysdeps/powerpc/initfini.c	Tue Oct 10 20:44:20 2000
@@ -0,0 +1 @@
+#include <sysdeps/generic/initfini-compat.c>
--- /dev/null	Thu Aug 24 02:00:32 2000
+++ sysdeps/generic/initfini-compat.c	Tue Oct 10 20:42:40 2000
@@ -0,0 +1,130 @@
+/* Special .init and .fini section support for binary compatibility.
+   Copyright (C) 2000 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it
+   and/or modify it under the terms of the GNU Library General Public
+   License as published by the Free Software Foundation; either
+   version 2 of the License, or (at your option) any later version.
+
+   In addition to the permissions in the GNU Library General Public
+   License, the Free Software Foundation gives you unlimited
+   permission to link the compiled version of this file with other
+   programs, and to distribute those programs without any restriction
+   coming from the use of this file.  (The Library General Public
+   License restrictions do apply in other respects; for example, they
+   cover modification of the file, and distribution when not linked
+   into another program.)
+
+   The GNU C Library is distributed in the hope that it will be
+   useful, but WITHOUT ANY WARRANTY; without even the implied warranty
+   of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+/* This file is compiled into assembly code which is then munged by a sed
+   script into two files: crti.s and crtn.s.
+
+   * crti.s puts a function prologue at the beginning of the
+   .init and .fini sections and defines global symbols for
+   those addresses, so they can be called as functions.
+
+   * crtn.s puts the corresponding function epilogues
+   in the .init and .fini sections. */
+
+#include <stdlib.h>
+
+/* We use embedded asm for .section unconditionally, as this makes it
+   easier to insert the necessary directives into crtn.S. */
+#define SECTION(x) asm (".section " x )
+
+/* Embed an #include to pull in the alignment and .end directives. */
+asm ("\n#include \"defs.h\"");
+
+/* The initial common code ends here. */
+asm ("\n/*@HEADER_ENDS*/");
+
+/* To determine whether we need .end and .align: */
+asm ("\n/*@TESTS_BEGIN*/");
+void
+dummy (void (*foo) (void))
+{
+  if (foo)
+    (*foo) ();
+}
+asm ("\n/*@TESTS_END*/");
+
+/* The beginning of _init:  */
+asm ("\n/*@_init_PROLOG_BEGINS*/");
+
+SECTION (".init");
+void
+_init (void)
+{
+  /* We cannot use the normal constructor mechanism in gcrt1.o because it
+     appears before crtbegin.o in the link, so the header elt of .ctors
+     would come after the elt for __gmon_start__.  One approach is for
+     gcrt1.o to reference a symbol which would be defined by some library
+     module which has a constructor; but then user code's constructors
+     would come first, and not be profiled.  */
+  extern void __gmon_start__ (void) __attribute__ ((weak)); /*weak_extern (__gmon_start__);*/
+  __gmon_start__ ();
+
+  asm ("ALIGN");
+  asm("END_INIT");
+  /* Now the epilog. */
+  asm ("\n/*@_init_PROLOG_ENDS*/");
+  asm ("\n/*@_init_EPILOG_BEGINS*/");
+  SECTION(".init");
+}
+asm ("END_INIT");
+SECTION(".text");
+
+/* This version of __gmon_start__ is used if no other is found.  By providing
+   a default function we avoid the need to test whether the pointer is NULL,
+   which can be painful on some machines.  */
+
+void __attribute__ ((weak))
+__gmon_start__ (void)
+{
+  /* do nothing */
+}
+
+/* End of the _init epilog, beginning of the _fini prolog. */
+asm ("\n/*@_init_EPILOG_ENDS*/");
+asm ("\n/*@_fini_PROLOG_BEGINS*/");
+
+SECTION (".fini");
+void
+_fini (void)
+{
+
+  /* End of the _fini prolog. */
+  asm ("ALIGN");
+  asm ("END_FINI");
+  asm ("\n/*@_fini_PROLOG_ENDS*/");
+
+  {
+    /* Let GCC know that _fini is not a leaf function by having a dummy
+       function call here.  We arrange for this call to be omitted from
+       either crt file.  */
+    extern void i_am_not_a_leaf (void);
+    i_am_not_a_leaf ();
+  }
+
+  /* Beginning of the _fini epilog. */
+  asm ("\n/*@_fini_EPILOG_BEGINS*/");
+  SECTION (".fini");
+}
+asm ("END_FINI");
+
+/* End of the _fini epilog.  Any further generated assembly (e.g. .ident)
+   is shared between both crt files. */
+asm ("\n/*@_fini_EPILOG_ENDS*/");
+asm ("\n/*@TRAILER_BEGINS*/");
+
+/* End of file. */