From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 31230 invoked by alias); 26 Sep 2002 22:31:04 -0000 Mailing-List: contact gdb-patches-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sources.redhat.com Received: (qmail 31161 invoked from network); 26 Sep 2002 22:31:02 -0000 Received: from unknown (HELO localhost.redhat.com) (216.138.202.10) by sources.redhat.com with SMTP; 26 Sep 2002 22:31:02 -0000 Received: from redhat.com (localhost [127.0.0.1]) by localhost.redhat.com (Postfix) with ESMTP id E0C2A3DC7; Thu, 26 Sep 2002 18:30:57 -0400 (EDT) Message-ID: <3D938AA1.6030801@redhat.com> Date: Thu, 26 Sep 2002 15:31:00 -0000 From: Andrew Cagney User-Agent: Mozilla/5.0 (X11; U; NetBSD macppc; en-US; rv:1.0.0) Gecko/20020824 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Kevin Buettner Cc: gdb-patches@sources.redhat.com Subject: Re: [rfa/ppc] Use frame_align(); delete hack References: <3D90F04C.9040900@redhat.com> <1020926183719.ZM19070@localhost.localdomain> Content-Type: multipart/mixed; boundary="------------020902030001000106050601" X-SW-Source: 2002-09/txt/msg00647.txt.bz2 This is a multi-part message in MIME format. --------------020902030001000106050601 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Content-length: 588 > > I think returning 0 here is a better idea. If the function that > you're returning from has made any (non-nullary) calls, r3 will have > been overwritten. Even if it doesn't make any calls, r3 is still fair > game for the compiler to use as a temporary. > > I'd like to see a comment pointing out the fact that gdb knows about > and is able to print struct return values in inferior function calls > due to the fact that gdb is the caller (and therefore knows the address > of the struct return buffer). Done. Two comments and a bug report. I checked in the attached. Andrew --------------020902030001000106050601 Content-Type: text/plain; name="diffs" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="diffs" Content-length: 4261 2002-09-26 Andrew Cagney * rs6000-tdep.c (rs6000_extract_struct_value_address): Return 0. (rs6000_struct_return_address): Delete variable. (rs6000_store_struct_return): Update. (rs6000_gdbarch_init): Set extract_struct_value_address instead of deprecated_extract_struct_value_address. (rs6000_frame_align): New function. (rs6000_gdbarch_init): Set frame_align. Index: rs6000-tdep.c =================================================================== RCS file: /cvs/src/src/gdb/rs6000-tdep.c,v retrieving revision 1.83 diff -u -r1.83 rs6000-tdep.c --- rs6000-tdep.c 25 Sep 2002 13:34:53 -0000 1.83 +++ rs6000-tdep.c 26 Sep 2002 22:27:24 -0000 @@ -1032,6 +1032,13 @@ } } +/* All the ABI's require 16 byte alignment. */ +static CORE_ADDR +rs6000_frame_align (struct gdbarch *gdbarch, CORE_ADDR addr) +{ + return (addr & -16); +} + /* Pass the arguments in either registers, or in the stack. In RS/6000, the first eight words of the argument list (that might be less than eight parameters if some parameters occupy more than one word) are @@ -1363,13 +1370,6 @@ } } -/* Keep structure return address in this variable. - FIXME: This is a horrid kludge which should not be allowed to continue - living. This only allows a single nested call to a structure-returning - function. Come on, guys! -- gnu@cygnus.com, Aug 92 */ - -static CORE_ADDR rs6000_struct_return_address; - /* Return whether handle_inferior_event() should proceed through code starting at PC in function NAME when stepping. @@ -1989,18 +1989,12 @@ } /* Store the address of the place in which to copy the structure the - subroutine will return. This is called from call_function. - - In RS/6000, struct return addresses are passed as an extra parameter in r3. - In function return, callee is not responsible of returning this address - back. Since gdb needs to find it, we will store in a designated variable - `rs6000_struct_return_address'. */ + subroutine will return. */ static void rs6000_store_struct_return (CORE_ADDR addr, CORE_ADDR sp) { write_register (3, addr); - rs6000_struct_return_address = addr; } /* Write into appropriate registers a function return value @@ -2058,9 +2052,20 @@ as a CORE_ADDR (or an expression that can be used as one). */ static CORE_ADDR -rs6000_extract_struct_value_address (char *regbuf) +rs6000_extract_struct_value_address (struct regcache *regcache) { - return rs6000_struct_return_address; + /* FIXME: cagney/2002-09-26: PR gdb/724: When making an inferior + function call GDB knows the address of the struct return value + and hence, should not need to call this function. Unfortunately, + the current hand_function_call() code only saves the most recent + struct address leading to occasional calls. The code should + instead maintain a stack of such addresses (in the dummy frame + object). */ + /* NOTE: cagney/2002-09-26: Return 0 which indicates that we've + really got no idea where the return value is being stored. While + r3, on function entry, contained the address it will have since + been reused (scratch) and hence wouldn't be valid */ + return 0; } /* Return whether PC is in a dummy function call. @@ -2887,6 +2892,7 @@ set_gdbarch_call_dummy_stack_adjust_p (gdbarch, 0); set_gdbarch_get_saved_register (gdbarch, generic_unwind_get_saved_register); set_gdbarch_fix_call_dummy (gdbarch, rs6000_fix_call_dummy); + set_gdbarch_frame_align (gdbarch, rs6000_frame_align); set_gdbarch_push_dummy_frame (gdbarch, generic_push_dummy_frame); set_gdbarch_save_dummy_frame_tos (gdbarch, generic_save_dummy_frame_tos); set_gdbarch_push_return_address (gdbarch, ppc_push_return_address); @@ -2910,7 +2916,7 @@ set_gdbarch_push_arguments (gdbarch, rs6000_push_arguments); set_gdbarch_store_struct_return (gdbarch, rs6000_store_struct_return); - set_gdbarch_deprecated_extract_struct_value_address (gdbarch, rs6000_extract_struct_value_address); + set_gdbarch_extract_struct_value_address (gdbarch, rs6000_extract_struct_value_address); set_gdbarch_pop_frame (gdbarch, rs6000_pop_frame); set_gdbarch_skip_prologue (gdbarch, rs6000_skip_prologue); --------------020902030001000106050601--