Normalize TRY_CATCH exception handling block

This normalizes some exception catch blocks that check for ex.reason
to look like this:

~~~
  volatile gdb_exception ex;

  TRY_CATCH (ex, RETURN_MASK_ALL)
    {
      ...
    }
  if (ex.reason < 0)
    {
      ...
    }
~~~

This is a preparation step for running a script that converts all
TRY_CATCH uses to look like this instead:

~~~
  TRY
    {
      ...
    }
  CATCH (ex, RETURN_MASK_ALL)
    {
      ...
    }
  END_CATCH
~~~

The motivation for that change is being able to reimplent TRY/CATCH in
terms of C++ try/catch.

This commit makes it so that:

 - no condition other than ex.reason < 0 is checked in the if
   predicate

 - there's no "else" block to check whether no exception was caught

 - there's no code between the TRY_CATCH (TRY) block and the
   'if (ex.reason < 0)' block (CATCH).

 - the exception object is no longer referred to outside the if/catch
   block.  Note the local volatile exception objects that are
   currently defined inside functions that use TRY_CATCH will
   disappear.  In cases it's more convenient to still refer to the
   exception outside the catch block, a new non-volatile local is
   added and copy to that object is made within the catch block.

The following patches should make this all clearer.

gdb/ChangeLog:
2015-03-07  Pedro Alves  <palves@redhat.com>

	* amd64-tdep.c (amd64_frame_cache, amd64_sigtramp_frame_cache)
	(amd64_epilogue_frame_cache): Normal exception handling code.
	* break-catch-throw.c (check_status_exception_catchpoint)
	(re_set_exception_catchpoint): Ditto.
	* cli/cli-interp.c (safe_execute_command):
	* cli/cli-script.c (script_from_file): Ditto.
	* compile/compile-c-symbols.c (generate_c_for_for_one_variable):
	Ditto.
	* compile/compile-object-run.c (compile_object_run): Ditto.
	* cp-abi.c (baseclass_offset): Ditto.
	* cp-valprint.c (cp_print_value): Ditto.
	* exceptions.c (catch_exceptions_with_msg):
	* frame-unwind.c (frame_unwind_try_unwinder): Ditto.
	* frame.c (get_frame_address_in_block_if_available): Ditto.
	* i386-tdep.c (i386_frame_cache, i386_epilogue_frame_cache)
	(i386_sigtramp_frame_cache): Ditto.
	* infcmd.c (post_create_inferior): Ditto.
	* linespec.c (parse_linespec, find_linespec_symbols):
	* p-valprint.c (pascal_object_print_value): Ditto.
	* parse.c (parse_expression_for_completion): Ditto.
	* python/py-finishbreakpoint.c (bpfinishpy_init): Ditto.
	* remote.c (remote_get_noisy_reply): Ditto.
	* s390-linux-tdep.c (s390_frame_unwind_cache): Ditto.
	* solib-svr4.c (solib_svr4_r_map): Ditto.

1 files changed, 23 insertions, 18 deletions

diff --git a/gdb/remote.c b/gdb/remote.c
index 495dfdc..eb1eb27 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -498,6 +498,7 @@ remote_get_noisy_reply (char **buf_p,
 	  char *p, *pp;
 	  int adjusted_size = 0;
 	  volatile struct gdb_exception ex;
+	  int relocated = 0;
 
 	  p = buf + strlen ("qRelocInsn:");
 	  pp = unpack_varlen_hex (p, &ul);
@@ -514,31 +515,35 @@ remote_get_noisy_reply (char **buf_p,
 	  TRY_CATCH (ex, RETURN_MASK_ALL)
 	    {
 	      gdbarch_relocate_instruction (target_gdbarch (), &to, from);
+	      relocated = 1;
 	    }
-	  if (ex.reason >= 0)
+	  if (ex.reason < 0)
+	    {
+	      if (ex.error == MEMORY_ERROR)
+		{
+		  /* Propagate memory errors silently back to the
+		     target.  The stub may have limited the range of
+		     addresses we can write to, for example.  */
+		}
+	      else
+		{
+		  /* Something unexpectedly bad happened.  Be verbose
+		     so we can tell what, and propagate the error back
+		     to the stub, so it doesn't get stuck waiting for
+		     a response.  */
+		  exception_fprintf (gdb_stderr, ex,
+				     _("warning: relocating instruction: "));
+		}
+	      putpkt ("E01");
+	    }
+
+	  if (relocated)
 	    {
 	      adjusted_size = to - org_to;
 
 	      xsnprintf (buf, *sizeof_buf, "qRelocInsn:%x", adjusted_size);
 	      putpkt (buf);
 	    }
-	  else if (ex.reason < 0 && ex.error == MEMORY_ERROR)
-	    {
-	      /* Propagate memory errors silently back to the target.
-		 The stub may have limited the range of addresses we
-		 can write to, for example.  */
-	      putpkt ("E01");
-	    }
-	  else
-	    {
-	      /* Something unexpectedly bad happened.  Be verbose so
-		 we can tell what, and propagate the error back to the
-		 stub, so it doesn't get stuck waiting for a
-		 response.  */
-	      exception_fprintf (gdb_stderr, ex,
-				 _("warning: relocating instruction: "));
-	      putpkt ("E01");
-	    }
 	}
       else if (buf[0] == 'O' && buf[1] != 'K')
 	remote_console_output (buf + 1);	/* 'O' message from stub */