From 61ff14c69a7cb2870f9dd2792690a1fbc8967f29 Mon Sep 17 00:00:00 2001 From: Jan Kratochvil Date: Sun, 15 Mar 2009 09:19:40 +0000 Subject: [PATCH] gdb/ * stack.c (return_command ): New variables retval_expr and old_chain. Inline parse_and_eval to initialize retval_expr. Check RETVAL_EXPR for UNOP_CAST and set RETURN_TYPE to the RETURN_VALUE type if RETURN_TYPE is NULL. gdb/doc/ * gdb.texinfo (Returning): New description for missing debug info. gdb/testsuite/ * gdb.base/return-nodebug.exp, gdb.base/return-nodebug.c: New. --- gdb/ChangeLog | 7 +++ gdb/doc/ChangeLog | 10 ++-- gdb/doc/gdb.texinfo | 47 +++++++++++++++++ gdb/stack.c | 13 ++++- gdb/testsuite/ChangeLog | 14 ++++-- gdb/testsuite/gdb.base/return-nodebug.c | 49 ++++++++++++++++++ gdb/testsuite/gdb.base/return-nodebug.exp | 61 +++++++++++++++++++++++ 7 files changed, 191 insertions(+), 10 deletions(-) create mode 100644 gdb/testsuite/gdb.base/return-nodebug.c create mode 100644 gdb/testsuite/gdb.base/return-nodebug.exp diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 71a74ea6a49..e5d892c69f4 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,10 @@ +2009-03-15 Jan Kratochvil + + * stack.c (return_command ): New variables retval_expr + and old_chain. Inline parse_and_eval to initialize retval_expr. Check + RETVAL_EXPR for UNOP_CAST and set RETURN_TYPE to the RETURN_VALUE type + if RETURN_TYPE is NULL. + 2009-03-14 Pedro Alves * remote.c (PACKET_qAttached): New. diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog index 65aa06bad2a..984011a6cf7 100644 --- a/gdb/doc/ChangeLog +++ b/gdb/doc/ChangeLog @@ -1,7 +1,11 @@ +2009-03-15 Jan Kratochvil + + * gdb.texinfo (Returning): New description for missing debug info. + 2009-03-14 Pedro Alves * gdb.texinfo (Remote Configuration): Document query-attached. - (General Query Packets): Document qAttached. + (General Query Packets): Document qAttached. 2009-03-05 Pedro Alves @@ -26,8 +30,8 @@ 2009-02-14 Vladimir Prus - * observer.texi: Add parameter 'print_frame' to normal_stop - observer. + * observer.texi: Add parameter 'print_frame' to normal_stop + observer. 2009-02-07 Eli Zaretskii diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index 33bac260a61..2ec680aa0d1 100644 --- a/gdb/doc/gdb.texinfo +++ b/gdb/doc/gdb.texinfo @@ -12494,6 +12494,53 @@ returned. In contrast, the @code{finish} command (@pxref{Continuing and Stepping, ,Continuing and Stepping}) resumes execution until the selected stack frame returns naturally. +@value{GDBN} needs to know how the @var{expression} argument should be set for +the inferior. The concrete registers assignment depends on the OS ABI and the +type being returned by the selected stack frame. For example it is common for +OS ABI to return floating point values in FPU registers while integer values in +CPU registers. Still some ABIs return even floating point values in CPU +registers. Larger integer widths (such as @code{long long int}) also have +specific placement rules. @value{GDBN} already knows the OS ABI from its +current target so it needs to find out also the type being returned to make the +assignment into the right register(s). + +Normally, the selected stack frame has debug info. @value{GDBN} will always +use the debug info instead of the implicit type of @var{expression} when the +debug info is available. For example, if you type @kbd{return -1}, and the +function in the current stack frame is declared to return a @code{long long +int}, @value{GDBN} transparently converts the implicit @code{int} value of -1 +into a @code{long long int}: + +@smallexample +Breakpoint 1, func () at gdb.base/return-nodebug.c:29 +29 return 31; +(@value{GDBP}) return -1 +Make func return now? (y or n) y +#0 0x004004f6 in main () at gdb.base/return-nodebug.c:43 +43 printf ("result=%lld\n", func ()); +(@value{GDBP}) +@end smallexample + +However, if the selected stack frame does not have a debug info, e.g., if the +function was compiled without debug info, @value{GDBN} has to find out the type +to return from user. Specifying a different type by mistake may set the value +in different inferior registers than the caller code expects. For example, +typing @kbd{return -1} with its implicit type @code{int} would set only a part +of a @code{long long int} result for a debug info less function (on 32-bit +architectures). Therefore the user is required to specify the return type by +an appropriate cast explicitly: + +@smallexample +Breakpoint 2, 0x0040050b in func () +(@value{GDBP}) return -1 +Return value type not available for selected stack frame. +Please use an explicit cast of the value to return. +(@value{GDBP}) return (long long int) -1 +Make selected stack frame return now? (y or n) y +#0 0x00400526 in main () +(@value{GDBP}) +@end smallexample + @node Calling @section Calling Program Functions diff --git a/gdb/stack.c b/gdb/stack.c index d0c872e497a..d0ea3bf8330 100644 --- a/gdb/stack.c +++ b/gdb/stack.c @@ -1796,18 +1796,27 @@ return_command (char *retval_exp, int from_tty) message. */ if (retval_exp) { + struct expression *retval_expr = parse_expression (retval_exp); + struct cleanup *old_chain = make_cleanup (xfree, retval_expr); struct type *return_type = NULL; /* Compute the return value. Should the computation fail, this call throws an error. */ - return_value = parse_and_eval (retval_exp); + return_value = evaluate_expression (retval_expr); /* Cast return value to the return type of the function. Should the cast fail, this call throws an error. */ if (thisfun != NULL) return_type = TYPE_TARGET_TYPE (SYMBOL_TYPE (thisfun)); if (return_type == NULL) - return_type = builtin_type (get_frame_arch (thisframe))->builtin_int; + { + if (retval_expr->elts[0].opcode != UNOP_CAST) + error (_("Return value type not available for selected " + "stack frame.\n" + "Please use an explicit cast of the value to return.")); + return_type = value_type (return_value); + } + do_cleanups (old_chain); CHECK_TYPEDEF (return_type); return_value = value_cast (return_type, return_value); diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog index b0474213882..e889d348cb8 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,7 @@ +2009-03-15 Jan Kratochvil + + * gdb.base/return-nodebug.exp, gdb.base/return-nodebug.c: New. + 2009-03-14 Jan Kratochvil Fix a racy FAIL. @@ -9,7 +13,7 @@ 2009-03-13 Vladimir Prus * gdb.mi/mi-cli.exp: Adjust for output difference in - sync and async modes. + sync and async modes. 2009-03-12 Joel Brobecker @@ -31,19 +35,19 @@ 2009-03-12 Vladimir Prus - * gdb.mi/mi-cli.exp: Remove debug print. + * gdb.mi/mi-cli.exp: Remove debug print. 2009-03-12 Vladimir Prus - * gdb.mi/mi-cli.exp: Verify that CLI commands that run inferior - include the token in ^running and frame info in *stopped. + * gdb.mi/mi-cli.exp: Verify that CLI commands that run inferior + include the token in ^running and frame info in *stopped. 2009-03-05 Paul Pluzhnikov * solib-display.exp: New file. * solib-display-main.c: New file. * solib-display-lib.c: New file. - + 2009-03-05 Pedro Alves * gdb.arch/i386-permbkpt.S, gdb.arch/i386-permbkpt.exp: New. diff --git a/gdb/testsuite/gdb.base/return-nodebug.c b/gdb/testsuite/gdb.base/return-nodebug.c new file mode 100644 index 00000000000..e1211b36049 --- /dev/null +++ b/gdb/testsuite/gdb.base/return-nodebug.c @@ -0,0 +1,49 @@ +/* This testcase is part of GDB, the GNU debugger. + + Copyright 2009 Free Software Foundation, Inc. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program 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 General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#include + +static TYPE +init (void) +{ + return 0; +} + +static TYPE +func (void) +{ + return 31; +} + +static void +marker (void) +{ +} + +int +main (void) +{ + /* Preinitialize registers to 0 to avoid false PASS by leftover garbage. */ + init (); + + printf ("result=" FORMAT "\n", CAST func ()); + + /* Cannot `next' with no debug info. */ + marker (); + + return 0; +} diff --git a/gdb/testsuite/gdb.base/return-nodebug.exp b/gdb/testsuite/gdb.base/return-nodebug.exp new file mode 100644 index 00000000000..7d43776762b --- /dev/null +++ b/gdb/testsuite/gdb.base/return-nodebug.exp @@ -0,0 +1,61 @@ +# Copyright (C) 2009 Free Software Foundation, Inc. + +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 3 of the License, or +# (at your option) any later version. +# +# This program 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 General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see . + +proc do_test {type} { + set typenospace [string map {{ } -} $type] + + global pf_prefix + set old_prefix $pf_prefix + lappend pf_prefix "$typenospace:" + + if {[runto "func"]} { + # Verify that we do not crash when using "return" from a function with + # no debugging info. Such function has no `struct symbol'. It may + # still have an associated `struct minimal_symbol'. + + gdb_test "return -1" \ + "Return value type not available for selected stack frame\\.\r\nPlease use an explicit cast of the value to return\\." \ + "return from function with no debug info without a cast" + + # Cast of the result to the proper width must be done explicitely. + gdb_test "return ($type) -1" "#0 .* main \\(.*" \ + "return from function with no debug info with a cast" \ + "Make selected stack frame return now\\? \\(y or n\\) " "y" + + # And if it returned the full width of the result. + gdb_test "adv marker" "\r\nresult=-1\r\n.* in marker \\(.*" \ + "full width of the returned result" + } + + set pf_prefix $old_prefix +} + +foreach case {{{signed char} %d (int)} \ + {{short} %d (int)} \ + {{int} %d} \ + {{long} %ld} \ + {{long long} %lld}} { + set type [lindex $case 0] + set format [lindex $case 1] + set cast [lindex $case 2] + + set typeesc [string map {{ } {\ }} $type] + set typenospace [string map {{ } -} $type] + + if {[prepare_for_testing return-nodebug.exp "return-nodebug-$typenospace" "return-nodebug.c" \ + [list "additional_flags=-DFORMAT=\"$format\" -DTYPE=$typeesc -DCAST=$cast"]] == 0} { + do_test $type + } +} -- 2.30.2