[PATCH 2/8] Add new gdbarch method, unconditional_branch_address

[Kevin Buettner <kevinb at redhat dot com>]

Add new gdbarch method, unconditional_branch_address.

gdb/ChangeLog:

    	* gdbarch.sh (unconditional_branch_address): New gdbarch method.
    	* gdbarch.h, gdbarch.c: Regenerate.
    	* arch-utils.h (default_unconditional_branch_address): Declare.
    	* arch-utils.c (default_unconditional_branch_address): New function.
---
 gdb/arch-utils.c |  6 ++++++
 gdb/arch-utils.h |  2 ++
 gdb/gdbarch.c    | 23 +++++++++++++++++++++++
 gdb/gdbarch.h    | 12 +++++++++++-
 gdb/gdbarch.sh   |  7 +++++++
 5 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/gdb/arch-utils.c b/gdb/arch-utils.c
index 7df5570..fbbb94c 100644
--- a/gdb/arch-utils.c
+++ b/gdb/arch-utils.c
@@ -820,6 +820,12 @@ default_gen_return_address (struct gdbarch *gdbarch,
   error (_("This architecture has no method to collect a return address."));
 }
 
+CORE_ADDR
+default_unconditional_branch_address (struct gdbarch *gdbarch, CORE_ADDR pc)
+{
+  return 0;
+}
+
 int
 default_return_in_first_hidden_param_p (struct gdbarch *gdbarch,
 					struct type *type)
diff --git a/gdb/arch-utils.h b/gdb/arch-utils.h
index 18e2290..1bad2c0 100644
--- a/gdb/arch-utils.h
+++ b/gdb/arch-utils.h
@@ -204,4 +204,6 @@ extern char *default_gcc_target_options (struct gdbarch *gdbarch);
 extern const char *default_gnu_triplet_regexp (struct gdbarch *gdbarch);
 extern int default_addressable_memory_unit_size (struct gdbarch *gdbarch);
 
+extern CORE_ADDR default_unconditional_branch_address (struct gdbarch *gdbarch, CORE_ADDR pc);
+
 #endif
diff --git a/gdb/gdbarch.c b/gdb/gdbarch.c
index 07b38a3..741dc10 100644
--- a/gdb/gdbarch.c
+++ b/gdb/gdbarch.c
@@ -330,6 +330,7 @@ struct gdbarch
   gdbarch_gcc_target_options_ftype *gcc_target_options;
   gdbarch_gnu_triplet_regexp_ftype *gnu_triplet_regexp;
   gdbarch_addressable_memory_unit_size_ftype *addressable_memory_unit_size;
+  gdbarch_unconditional_branch_address_ftype *unconditional_branch_address;
 };
 
 /* Create a new ``struct gdbarch'' based on information provided by
@@ -432,6 +433,7 @@ gdbarch_alloc (const struct gdbarch_info *info,
   gdbarch->gcc_target_options = default_gcc_target_options;
   gdbarch->gnu_triplet_regexp = default_gnu_triplet_regexp;
   gdbarch->addressable_memory_unit_size = default_addressable_memory_unit_size;
+  gdbarch->unconditional_branch_address = default_unconditional_branch_address;
   /* gdbarch_alloc() */
 
   return gdbarch;
@@ -666,6 +668,7 @@ verify_gdbarch (struct gdbarch *gdbarch)
   /* Skip verify of gcc_target_options, invalid_p == 0 */
   /* Skip verify of gnu_triplet_regexp, invalid_p == 0 */
   /* Skip verify of addressable_memory_unit_size, invalid_p == 0 */
+  /* Skip verify of unconditional_branch_address, invalid_p == 0 */
   buf = ui_file_xstrdup (log, &length);
   make_cleanup (xfree, buf);
   if (length > 0)
@@ -1356,6 +1359,9 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
                       "gdbarch_dump: target_desc = %s\n",
                       host_address_to_string (gdbarch->target_desc));
   fprintf_unfiltered (file,
+                      "gdbarch_dump: unconditional_branch_address = <%s>\n",
+                      host_address_to_string (gdbarch->unconditional_branch_address));
+  fprintf_unfiltered (file,
                       "gdbarch_dump: gdbarch_unwind_pc_p() = %d\n",
                       gdbarch_unwind_pc_p (gdbarch));
   fprintf_unfiltered (file,
@@ -4753,6 +4759,23 @@ set_gdbarch_addressable_memory_unit_size (struct gdbarch *gdbarch,
   gdbarch->addressable_memory_unit_size = addressable_memory_unit_size;
 }
 
+CORE_ADDR
+gdbarch_unconditional_branch_address (struct gdbarch *gdbarch, CORE_ADDR pc)
+{
+  gdb_assert (gdbarch != NULL);
+  gdb_assert (gdbarch->unconditional_branch_address != NULL);
+  if (gdbarch_debug >= 2)
+    fprintf_unfiltered (gdb_stdlog, "gdbarch_unconditional_branch_address called\n");
+  return gdbarch->unconditional_branch_address (gdbarch, pc);
+}
+
+void
+set_gdbarch_unconditional_branch_address (struct gdbarch *gdbarch,
+                                          gdbarch_unconditional_branch_address_ftype unconditional_branch_address)
+{
+  gdbarch->unconditional_branch_address = unconditional_branch_address;
+}
+
 
 /* Keep a registry of per-architecture data-pointers required by GDB
    modules.  */
diff --git a/gdb/gdbarch.h b/gdb/gdbarch.h
index c1e2c1a..1770960 100644
--- a/gdb/gdbarch.h
+++ b/gdb/gdbarch.h
@@ -924,7 +924,7 @@ extern void set_gdbarch_max_insn_length (struct gdbarch *gdbarch, ULONGEST max_i
    If your architecture doesn't need to adjust instructions before
    single-stepping them, consider using simple_displaced_step_copy_insn
    here.
-
+  
    If the instruction cannot execute out of line, return NULL.  The
    core falls back to stepping past the instruction in-line instead in
    that case. */
@@ -1478,6 +1478,16 @@ typedef int (gdbarch_addressable_memory_unit_size_ftype) (struct gdbarch *gdbarc
 extern int gdbarch_addressable_memory_unit_size (struct gdbarch *gdbarch);
 extern void set_gdbarch_addressable_memory_unit_size (struct gdbarch *gdbarch, gdbarch_addressable_memory_unit_size_ftype *addressable_memory_unit_size);
 
+/* Examine instruction at PC.  If instruction at PC is an unconditional
+   branch, return the address to which control is transferred when the
+   branch is taken.  Return 0 when this method is not implemented by
+   architecture, PC refers to an invalid address, or instruction at PC
+   is not an unconditional branch. */
+
+typedef CORE_ADDR (gdbarch_unconditional_branch_address_ftype) (struct gdbarch *gdbarch, CORE_ADDR pc);
+extern CORE_ADDR gdbarch_unconditional_branch_address (struct gdbarch *gdbarch, CORE_ADDR pc);
+extern void set_gdbarch_unconditional_branch_address (struct gdbarch *gdbarch, gdbarch_unconditional_branch_address_ftype *unconditional_branch_address);
+
 /* Definition for an unknown syscall, used basically in error-cases.  */
 #define UNKNOWN_SYSCALL (-1)
 
diff --git a/gdb/gdbarch.sh b/gdb/gdbarch.sh
index 994a87b..c70d241 100755
--- a/gdb/gdbarch.sh
+++ b/gdb/gdbarch.sh
@@ -1123,6 +1123,13 @@ m:const char *:gnu_triplet_regexp:void:::default_gnu_triplet_regexp::0
 # each address in memory.
 m:int:addressable_memory_unit_size:void:::default_addressable_memory_unit_size::0
 
+# Examine instruction at PC.  If instruction at PC is an unconditional
+# branch, return the address to which control is transferred when the
+# branch is taken.  Return 0 when this method is not implemented by
+# architecture, PC refers to an invalid address, or instruction at PC
+# is not an unconditional branch.
+m:CORE_ADDR:unconditional_branch_address:CORE_ADDR pc:pc::default_unconditional_branch_address::0
+
 EOF
 }