Index: gdbarch.sh
===================================================================
RCS file: /cvs/src/src/gdb/gdbarch.sh,v
retrieving revision 1.288
diff -u -p -r1.288 gdbarch.sh
--- gdbarch.sh	14 Nov 2003 21:22:42 -0000	1.288
+++ gdbarch.sh	2 Dec 2003 03:52:38 -0000
@@ -771,6 +771,24 @@ F::FETCH_POINTER_ARGUMENT:CORE_ADDR:fetc
 # Return the appropriate register set for a core file section with
 # name SECT_NAME and size SECT_SIZE.
 M:::const struct regset *:regset_from_core_section:const char *sect_name, size_t sect_size:sect_name, sect_size
+
+# Return nonzero if PC points to the first "effective" instruction of
+# the function starting at FUNC_START.
+#
+# The default implementation which should be appropriate for most
+# targets is to return nonzero if PC is equal to FUNC_START.  However,
+# it can happen that the address of a subroutine call instruction
+# is changed to jump slightly after the begining of the function,
+# thus making the "effective" function start address a bit different
+# from the start address read from the symbol table or the debugging
+# information.
+#
+# For instance, on alpha-tru64, the first two instructions of a function
+# are often setting up the GP. The linker sometimes determines that
+# these instructions are not needed for the proper execution of the
+# program and therefore virtually optimizes them out by changing the
+# jump address to branch 2 instructions later.
+f:2:AT_FUNCTION_START:int:at_function_start:CORE_ADDR pc, CORE_ADDR func_start:pc, func_start::0:default_at_function_start::0
 EOF
 }
 
Index: arch-utils.c
===================================================================
RCS file: /cvs/src/src/gdb/arch-utils.c,v
retrieving revision 1.108
diff -u -p -r1.108 arch-utils.c
--- arch-utils.c	14 Nov 2003 21:22:42 -0000	1.108
+++ arch-utils.c	2 Dec 2003 03:52:39 -0000
@@ -370,6 +370,12 @@ default_stabs_argument_has_addr (struct 
   return 0;
 }
 
+int
+default_at_function_start (CORE_ADDR pc, CORE_ADDR func_start)
+{
+  return pc == func_start;
+}
+
 
 /* Functions to manipulate the endianness of the target.  */
 
Index: arch-utils.h
===================================================================
RCS file: /cvs/src/src/gdb/arch-utils.h,v
retrieving revision 1.65
diff -u -p -r1.65 arch-utils.h
--- arch-utils.h	23 Nov 2003 21:32:42 -0000	1.65
+++ arch-utils.h	2 Dec 2003 03:52:39 -0000
@@ -142,6 +142,8 @@ extern void legacy_value_to_register (st
 extern int default_stabs_argument_has_addr (struct gdbarch *gdbarch,
 					    struct type *type);
 
+extern int default_at_function_start (CORE_ADDR pc, CORE_ADDR func_start);
+
 /* For compatibility with older architectures, returns
    (LEGACY_SIM_REGNO_IGNORE) when the register doesn't have a valid
    name.  */
Index: infrun.c
===================================================================
RCS file: /cvs/src/src/gdb/infrun.c,v
retrieving revision 1.122
diff -u -p -r1.122 infrun.c
--- infrun.c	25 Nov 2003 16:01:36 -0000	1.122
+++ infrun.c	2 Dec 2003 03:52:41 -0000
@@ -2472,7 +2472,7 @@ process_event_stop_test:
       return;
     }
 
-  if (((stop_pc == ecs->stop_func_start	/* Quick test */
+  if (((AT_FUNCTION_START (stop_pc, ecs->stop_func_start)
 	|| in_prologue (stop_pc, ecs->stop_func_start))
        && !IN_SOLIB_RETURN_TRAMPOLINE (stop_pc, ecs->stop_func_name))
       || IN_SOLIB_CALL_TRAMPOLINE (stop_pc, ecs->stop_func_name)
Index: alpha-osf1-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/alpha-osf1-tdep.c,v
retrieving revision 1.16
diff -u -p -r1.16 alpha-osf1-tdep.c
--- alpha-osf1-tdep.c	27 Aug 2003 19:02:03 -0000	1.16
+++ alpha-osf1-tdep.c	2 Dec 2003 03:52:41 -0000
@@ -45,6 +45,47 @@ alpha_osf1_sigcontext_addr (struct frame
     return (read_memory_integer (get_frame_base (frame), 8));
 }
 
+static int
+alpha_osf1_at_function_start (CORE_ADDR pc, CORE_ADDR func_start)
+{
+  /* A function prologue typically starts with 2 instructions setting
+     up the GP.  But the linker sometimes changes the jump address of
+     subroutine calls because it has determined that these 2 instructions
+     do not make any difference in the execution of the program.  So it
+     has virtually optimized them out by changing the jump address
+     inside the function call to branch just after these 2 instructions.
+
+     As a consequence, the "effective" start address of a given function
+     can be either the first instruction of this function, or the third
+     instruction if the first two instructions are setting up the GP.
+     
+     It is important to recognize these two cases during a "next" in
+     order to properly detect function calls that land into a prologueless
+     function which first two instructions have been shunted by the linker.  */
+
+  if (pc == func_start)
+    return 1;
+
+  if (pc == func_start + 8)
+    {
+      unsigned int inst;
+
+      /* ldah $gp,n($t12) */
+      inst = alpha_read_insn (func_start);
+      if ((inst & 0xffff0000) != 0x27bb0000)
+        return 0;
+
+      /* lda $gp,n($gp) */
+      inst = alpha_read_insn (func_start + 4);
+      if ((inst & 0xffff0000) != 0x23bd0000)
+        return 0;
+
+      return 1;
+    }
+
+  return 0;
+}
+
 static void
 alpha_osf1_init_abi (struct gdbarch_info info,
                      struct gdbarch *gdbarch)
@@ -59,6 +100,7 @@ alpha_osf1_init_abi (struct gdbarch_info
      on multi-processor machines. We need to use software single stepping
      instead.  */
   set_gdbarch_software_single_step (gdbarch, alpha_software_single_step);
+  set_gdbarch_at_function_start (gdbarch, alpha_osf1_at_function_start);
 
   tdep->sigcontext_addr = alpha_osf1_sigcontext_addr;