From 6b454703a5a53bee1355b5a871a10f6bbfcde64e Mon Sep 17 00:00:00 2001 From: Mark Wielaard Date: Tue, 9 Dec 2014 11:45:41 +0100 Subject: [PATCH] Use GCC5/DWARF5 DW_AT_noreturn to mark functions that don't return normally. Add a flag field is_noreturn to struct func_type. Make calling_convention a small bit field to not increase the size of the struct. Set is_noreturn if the new GCC5/DWARF5 DW_AT_noreturn is set on a DW_TAG_subprogram. Use this information to warn the user before doing a finish or return from a function that does not return normally to its caller. (gdb) finish warning: Function endless does not return normally. Try to finish anyway? (y or n) (gdb) return warning: Function does not return normally to caller. Make endless return now? (y or n) gdb/ChangeLog * dwarf2read.c (read_subroutine_type): Set TYPE_NO_RETURN from DW_AT_noreturn. * gdbtypes.h (struct func_type): Add is_noreturn field flag. Make calling_convention an 8 bit bit field. (TYPE_NO_RETURN): New macro. * infcmd.c (finish_command): Query if function does not return normally. * stack.c (return_command): Likewise. include/ChangeLog * dwarf2.def (DW_AT_noreturn): New DWARF5 attribute. The dwarf2.h addition and the code to emit the new attribute is already in the gcc tree. --- gdb/ChangeLog | 11 +++++++++++ gdb/dwarf2read.c | 6 ++++++ gdb/gdbtypes.h | 12 ++++++++++-- gdb/infcmd.c | 9 ++++++++- gdb/stack.c | 8 ++++++-- include/ChangeLog | 4 ++++ include/dwarf2.def | 2 ++ 7 files changed, 47 insertions(+), 5 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index ad845a7..43a62af 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,14 @@ +2014-12-09 Mark Wielaard + + * dwarf2read.c (read_subroutine_type): Set TYPE_NO_RETURN from + DW_AT_noreturn. + * gdbtypes.h (struct func_type): Add is_noreturn field flag. Make + calling_convention an 8 bit bit field. + (TYPE_NO_RETURN): New macro. + * infcmd.c (finish_command): Query if function does not return + normally. + * stack.c (return_command): Likewise. + 2014-12-08 Doug Evans * python/py-objfile.c (objfpy_get_owner): Increment refcount of result. diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c index 829611d..90e7893 100644 --- a/gdb/dwarf2read.c +++ b/gdb/dwarf2read.c @@ -14308,6 +14308,12 @@ read_subroutine_type (struct die_info *die, struct dwarf2_cu *cu) else TYPE_CALLING_CONVENTION (ftype) = DW_CC_normal; + /* Record whether the function returns normally to its caller or not + if the DWARF producer set that information. */ + attr = dwarf2_attr (die, DW_AT_noreturn, cu); + if (attr && (DW_UNSND (attr) != 0)) + TYPE_NO_RETURN (ftype) = 1; + /* We need to add the subroutine type to the die immediately so we don't infinitely recurse when dealing with parameters declared as the same subroutine type. */ diff --git a/gdb/gdbtypes.h b/gdb/gdbtypes.h index a56f543..2806c4d 100644 --- a/gdb/gdbtypes.h +++ b/gdb/gdbtypes.h @@ -1019,9 +1019,16 @@ struct func_type { /* * The calling convention for targets supporting multiple ABIs. Right now this is only fetched from the Dwarf-2 - DW_AT_calling_convention attribute. */ + DW_AT_calling_convention attribute. The value is one of the + DW_CC enum dwarf_calling_convention constants. */ - unsigned calling_convention; + unsigned calling_convention : 8; + + /* * Whether this function normally returns to its caller. It is + set from the DW_AT_noreturn attribute if set on the + DW_TAG_subprogram. */ + + unsigned int is_noreturn : 1; /* * Only those DW_TAG_GNU_call_site's in this function that have DW_AT_GNU_tail_call set are linked in this list. Function @@ -1245,6 +1252,7 @@ extern void allocate_gnat_aux_type (struct type *); #define TYPE_GNAT_SPECIFIC(thistype) TYPE_MAIN_TYPE(thistype)->type_specific.gnat_stuff #define TYPE_DESCRIPTIVE_TYPE(thistype) TYPE_GNAT_SPECIFIC(thistype)->descriptive_type #define TYPE_CALLING_CONVENTION(thistype) TYPE_MAIN_TYPE(thistype)->type_specific.func_stuff->calling_convention +#define TYPE_NO_RETURN(thistype) TYPE_MAIN_TYPE(thistype)->type_specific.func_stuff->is_noreturn #define TYPE_TAIL_CALL_LIST(thistype) TYPE_MAIN_TYPE(thistype)->type_specific.func_stuff->tail_call_list #define TYPE_BASECLASS(thistype,index) TYPE_FIELD_TYPE(thistype, index) #define TYPE_N_BASECLASSES(thistype) TYPE_CPLUS_SPECIFIC(thistype)->n_baseclasses diff --git a/gdb/infcmd.c b/gdb/infcmd.c index 4415b31..68d9ef9 100644 --- a/gdb/infcmd.c +++ b/gdb/infcmd.c @@ -1869,7 +1869,14 @@ finish_command (char *arg, int from_tty) if (execution_direction == EXEC_REVERSE) printf_filtered (_("Run back to call of ")); else - printf_filtered (_("Run till exit from ")); + { + if (function != NULL && TYPE_NO_RETURN (function->type) + && !query (_("warning: Function %s does not return normally.\n" + "Try to finish anyway? "), + SYMBOL_PRINT_NAME (function))) + error (_("Not confirmed.")); + printf_filtered (_("Run till exit from ")); + } print_stack_frame (get_selected_frame (NULL), 1, LOCATION, 0); } diff --git a/gdb/stack.c b/gdb/stack.c index 2834801..f7e77e4 100644 --- a/gdb/stack.c +++ b/gdb/stack.c @@ -2462,8 +2462,12 @@ return_command (char *retval_exp, int from_tty) confirmed = query (_("%sMake selected stack frame return now? "), query_prefix); else - confirmed = query (_("%sMake %s return now? "), query_prefix, - SYMBOL_PRINT_NAME (thisfun)); + { + if (TYPE_NO_RETURN (thisfun->type)) + warning ("Function does not return normally to caller."); + confirmed = query (_("%sMake %s return now? "), query_prefix, + SYMBOL_PRINT_NAME (thisfun)); + } if (!confirmed) error (_("Not confirmed")); } diff --git a/include/ChangeLog b/include/ChangeLog index e80d2ec..69ed996 100644 --- a/include/ChangeLog +++ b/include/ChangeLog @@ -1,3 +1,7 @@ +2014-12-09 Mark Wielaard + + * dwarf2.def (DW_AT_noreturn): New DWARF5 attribute. + 2014-12-06 Eric Botcazou * dis-asm.h (print_insn_visium): Declare. diff --git a/include/dwarf2.def b/include/dwarf2.def index 8ca143c..8533a3e 100644 --- a/include/dwarf2.def +++ b/include/dwarf2.def @@ -308,6 +308,8 @@ DW_AT (DW_AT_data_bit_offset, 0x6b) DW_AT (DW_AT_const_expr, 0x6c) DW_AT (DW_AT_enum_class, 0x6d) DW_AT (DW_AT_linkage_name, 0x6e) +/* DWARF 5. */ +DW_AT (DW_AT_noreturn, 0x87) DW_AT_DUP (DW_AT_lo_user, 0x2000) /* Implementation-defined range start. */ DW_AT_DUP (DW_AT_hi_user, 0x3fff) /* Implementation-defined range end. */ -- 1.8.3.1