From 31db7b6c38e66697f1353f6fbfba62c306d84240 Mon Sep 17 00:00:00 2001 From: Mark Kettenis Date: Sat, 8 May 2004 23:02:10 +0000 Subject: [PATCH] * defs.h (enum return_value_convention): Add RETURN_VALUE_ABI_RETURNS_ADDRESS and RETURN_VALUE_ABI_PRESERVES_ADDRESS. * infcmd.c (legacy_return_value): New function. (print_return_value): Rwerite to implement RETURN_VALUE_ABI_RETURNS_ADDRESS. * values.c (using_struct_return): Check for inequality to RETURN_VALUE_REGISTER_CONVENTION instead of equality to RETURN_VALUE_STRUCT_CONVENTION. * i386-tdep.c (i386_return_value): Implement RETURN_VALUE_ABI_RETURNS_ADDRESS. --- gdb/ChangeLog | 12 +++++ gdb/defs.h | 14 +++++- gdb/i386-tdep.c | 23 ++++++++- gdb/infcmd.c | 126 +++++++++++++++++++++++++++--------------------- gdb/values.c | 2 +- 5 files changed, 120 insertions(+), 57 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 461e9f6d53..13e3a6ac0d 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,5 +1,17 @@ 2004-05-09 Mark Kettenis + * defs.h (enum return_value_convention): Add + RETURN_VALUE_ABI_RETURNS_ADDRESS and + RETURN_VALUE_ABI_PRESERVES_ADDRESS. + * infcmd.c (legacy_return_value): New function. + (print_return_value): Rwerite to implement + RETURN_VALUE_ABI_RETURNS_ADDRESS. + * values.c (using_struct_return): Check for inequality to + RETURN_VALUE_REGISTER_CONVENTION instead of equality to + RETURN_VALUE_STRUCT_CONVENTION. + * i386-tdep.c (i386_return_value): Implement + RETURN_VALUE_ABI_RETURNS_ADDRESS. + * vax-tdep.c: Tweak comments. Reorder include files. Don't include "symtab.h", "opcode/vax.h" and "inferior.h". (vax_skip_prologue): Replace calls to read_memory_integer by calls diff --git a/gdb/defs.h b/gdb/defs.h index 362f4a773c..9771428522 100644 --- a/gdb/defs.h +++ b/gdb/defs.h @@ -250,7 +250,19 @@ enum return_value_convention should be stored. While typically, and historically, used for large structs, this is convention is applied to values of many different types. */ - RETURN_VALUE_STRUCT_CONVENTION + RETURN_VALUE_STRUCT_CONVENTION, + /* Like the "struct return convention" above, but where the ABI + guarantees that the called function stores the address at which + the value being returned is stored in a well-defined location, + such as a register or memory slot in the stack frame. Don't use + this if the ABI doesn't explicitly guarantees this. */ + RETURN_VALUE_ABI_RETURNS_ADDRESS, + /* Like the "struct return convention" above, but where the ABI + guarantees that the address at which the value being returned is + stored will be available in a well-defined location, such as a + register or memory slot in the stack frame. Don't use this if + the ABI doesn't explicitly guarantees this. */ + RETURN_VALUE_ABI_PRESERVES_ADDRESS, }; /* the cleanup list records things that have to be undone diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c index 8542ef9f76..5f3952931f 100644 --- a/gdb/i386-tdep.c +++ b/gdb/i386-tdep.c @@ -1352,7 +1352,28 @@ i386_return_value (struct gdbarch *gdbarch, struct type *type, if ((code == TYPE_CODE_STRUCT || code == TYPE_CODE_UNION) && !i386_reg_struct_return_p (gdbarch, type)) - return RETURN_VALUE_STRUCT_CONVENTION; + { + /* The System V ABI says that: + + "A function that returns a structure or union also sets %eax + to the value of the original address of the caller's area + before it returns. Thus when the caller receives control + again, the address of the returned object resides in register + %eax and can be used to access the object." + + So the ABI guarantees that we can always find the return + value just after the function has returned. */ + + if (readbuf) + { + ULONGEST addr; + + regcache_raw_read_unsigned (regcache, I386_EAX_REGNUM, &addr); + read_memory (addr, readbuf, TYPE_LENGTH (type)); + } + + return RETURN_VALUE_ABI_RETURNS_ADDRESS; + } /* This special case is for structures consisting of a single `float' or `double' member. These structures are returned in diff --git a/gdb/infcmd.c b/gdb/infcmd.c index bedc5a541e..2cbfce3c38 100644 --- a/gdb/infcmd.c +++ b/gdb/infcmd.c @@ -1047,79 +1047,97 @@ advance_command (char *arg, int from_tty) } -/* Print the result of a function at the end of a 'finish' command. */ - -static void -print_return_value (int struct_return, struct type *value_type) +static struct value * +legacy_return_value (int struct_return, struct type *value_type) { - struct cleanup *old_chain; - struct ui_stream *stb; struct value *value; if (!struct_return) { /* The return value can be found in the inferior's registers. */ - value = register_value_being_returned (value_type, stop_registers); + return register_value_being_returned (value_type, stop_registers); } - /* FIXME: cagney/2004-01-17: When both return_value and - extract_returned_value_address are available, should use that to - find the address of and then extract the returned value. */ + + if (DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS_P ()) + { + CORE_ADDR addr; + + addr = DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS (stop_registers); + if (!addr) + error ("Function return value unknown."); + return value_at (value_type, addr, NULL); + } + + /* It is "struct return" yet the value is being extracted, + presumably from registers, using EXTRACT_RETURN_VALUE. This + doesn't make sense. Unfortunately, the legacy interfaces allowed + this behavior. Sigh! */ + value = allocate_value (value_type); + CHECK_TYPEDEF (value_type); + /* If the function returns void, don't bother fetching the return + value. */ + EXTRACT_RETURN_VALUE (value_type, stop_registers, + VALUE_CONTENTS_RAW (value)); + return value; +} + +/* Print the result of a function at the end of a 'finish' command. */ + +static void +print_return_value (int struct_return, struct type *value_type) +{ + struct gdbarch *gdbarch = current_gdbarch; + struct cleanup *old_chain; + struct ui_stream *stb; + struct value *value = NULL; + /* FIXME: 2003-09-27: When returning from a nested inferior function call, it's possible (with no help from the architecture vector) to locate and return/print a "struct return" value. This is just a more complicated case of what is already being done in in the inferior function call code. In fact, when inferior function calls are made async, this will likely be made the norm. */ - else if (gdbarch_return_value_p (current_gdbarch)) - /* We cannot determine the contents of the structure because it is - on the stack, and we don't know where, since we did not - initiate the call, as opposed to the call_function_by_hand - case. */ + + if (gdbarch_return_value_p (gdbarch)) + { + switch (gdbarch_return_value (gdbarch, value_type, NULL, NULL, NULL)) + { + case RETURN_VALUE_REGISTER_CONVENTION: + case RETURN_VALUE_ABI_RETURNS_ADDRESS: + value = allocate_value (value_type); + CHECK_TYPEDEF (value_type); + gdbarch_return_value (current_gdbarch, value_type, stop_registers, + VALUE_CONTENTS_RAW (value), NULL); + break; + + case RETURN_VALUE_STRUCT_CONVENTION: + break; + } + } + else + value = legacy_return_value (struct_return, value_type); + + if (value) + { + /* Print it. */ + stb = ui_out_stream_new (uiout); + old_chain = make_cleanup_ui_out_stream_delete (stb); + ui_out_text (uiout, "Value returned is "); + ui_out_field_fmt (uiout, "gdb-result-var", "$%d", + record_latest_value (value)); + ui_out_text (uiout, " = "); + value_print (value, stb->stream, 0, Val_no_prettyprint); + ui_out_field_stream (uiout, "return-value", stb); + ui_out_text (uiout, "\n"); + do_cleanups (old_chain); + } + else { - gdb_assert (gdbarch_return_value (current_gdbarch, value_type, - NULL, NULL, NULL) - == RETURN_VALUE_STRUCT_CONVENTION); ui_out_text (uiout, "Value returned has type: "); ui_out_field_string (uiout, "return-type", TYPE_NAME (value_type)); ui_out_text (uiout, "."); ui_out_text (uiout, " Cannot determine contents\n"); - return; } - else - { - if (DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS_P ()) - { - CORE_ADDR addr = DEPRECATED_EXTRACT_STRUCT_VALUE_ADDRESS (stop_registers); - if (!addr) - error ("Function return value unknown."); - value = value_at (value_type, addr, NULL); - } - else - { - /* It is "struct return" yet the value is being extracted, - presumably from registers, using EXTRACT_RETURN_VALUE. - This doesn't make sense. Unfortunately, the legacy - interfaces allowed this behavior. Sigh! */ - value = allocate_value (value_type); - CHECK_TYPEDEF (value_type); - /* If the function returns void, don't bother fetching the - return value. */ - EXTRACT_RETURN_VALUE (value_type, stop_registers, - VALUE_CONTENTS_RAW (value)); - } - } - - /* Print it. */ - stb = ui_out_stream_new (uiout); - old_chain = make_cleanup_ui_out_stream_delete (stb); - ui_out_text (uiout, "Value returned is "); - ui_out_field_fmt (uiout, "gdb-result-var", "$%d", - record_latest_value (value)); - ui_out_text (uiout, " = "); - value_print (value, stb->stream, 0, Val_no_prettyprint); - ui_out_field_stream (uiout, "return-value", stb); - ui_out_text (uiout, "\n"); - do_cleanups (old_chain); } /* Stuff that needs to be done by the finish command after the target diff --git a/gdb/values.c b/gdb/values.c index 87baf2144b..f468ff8abf 100644 --- a/gdb/values.c +++ b/gdb/values.c @@ -1308,7 +1308,7 @@ using_struct_return (struct type *value_type, int gcc_p) /* Probe the architecture for the return-value convention. */ return (gdbarch_return_value (current_gdbarch, value_type, NULL, NULL, NULL) - == RETURN_VALUE_STRUCT_CONVENTION); + != RETURN_VALUE_REGISTER_CONVENTION); } void