"break LINENO/*ADDRESS", inline functions and "info break" output

While experimenting with the previous patch, I noticed this inconsistency
in GDB's output:

  (gdb) b 32
  Breakpoint 1 at 0x40062f: file inline-break.c, line 32.                  (1)
  (gdb) r
  ....
  Breakpoint 1, func1 (x=1) at inline-break.c:32                           (2)
  32        return x * 23; /* break here */
  (gdb) info breakpoints
  Num     Type           Disp Enb Address    What
  1       breakpoint     keep y   0x40062f   in main at inline-break.c:32  (3)
	  breakpoint already hit 1 time
  (gdb)

Notice that when the breakpoint as set, GDB showed "inline-break.c,
line 32" (1), the same line number that was specified in the command.

When we run to the breakpoint, we present the stop at the same line
number, and correctly show "func1" as the function name (2).

But in "info break" output (3), notice that we say "in main", not "in
func1".

The same thing happens if you set a breakpoint by address.  I.e.:

  (gdb) b *0x40062f
  Breakpoint 2 at 0x40062f: file inline-break.c, line 32.
  (gdb) info breakpoints
  Num     Type           Disp Enb Address            What
  2       breakpoint     keep y   0x000000000040062f in main at inline-break.c:32
   (gdb) r
   ....
  Breakpoint 2, func1 (x=1) at inline-break.c:32
  32        return x * 23; /* break here */

The problem is that the breakpoints were set at an inline function,
but when we set such a breakpoint by line number or address, we don't
record the functions symbol in the sal, and as consequence the
breakpoint location does not have an associated symbol either.

Then, in print_breakpoint_location, if the location does not have a
symbol, we call find_pc_sect_function to find one, and this is what
finds "main", because find_pc_sect_function uses
block_linkage_function:

  /* Return the symbol for the function which contains a specified
     lexical block, described by a struct block BL.  The return value
     will not be an inlined function; the containing function will be
     returned instead.  */

  struct symbol *
  block_linkage_function (const struct block *bl)

To fix this, this commit adds an alternative to find_pc_sect_function
that uses block_containing_function instead:

  /* Return the symbol for the function which contains a specified
     block, described by a struct block BL.  The return value will be
     the closest enclosing function, which might be an inline
     function.  */

  struct symbol *
  block_containing_function (const struct block *bl)

(It seems odd to me that block_linkage_function says "the CONTAINING
function will be returned", and then block_containing_function says it
returns "the closest enclosing function".  Something seems reversed
here.  Still, I've kept the same nomenclature and copied the comments,
so that at least there's consistency.  Maybe we should fix that up
somehow.)

Then I wondered, why make print_breakpoint_location look up the symbol
every time it is called, instead of just always storing the symbol
when the location is created, since the location already stores the
symbol in some cases.  So to find which cases might be missing setting
the symbol in the sal which is used to create the breakpoint location,
I added an assertion to print_breakpoint_location, and ran the
testsuite.  That caught a few places, unsurprisingly:

 - setting a breakpoint by line number
 - setting a breapoint by address
 - ifunc resolving

Those are all fixed by this commit.  I decided not to add the
assertion to block_linkage_function and leave the existing "if (sym)"
check in place, because it's plausible that we have symtabs with line
info but no symbols.  I.e., that would not be a GDB bug, but
a peculiarity of debug info input.

gdb/ChangeLog:
2018-06-29  Pedro Alves  <palves@redhat.com>

	* blockframe.c (find_pc_sect_containing_function): New function.
	* breakpoint.c (print_breakpoint_location): Don't call
	find_pc_sect_function.
	* linespec.c (create_sals_line_offset): Record the location's
	symbol in the sal.
	* linespec.c (convert_address_location_to_sals): Fill in sal's
	symbol with find_pc_sect_containing_function.
	* symtab.c (find_function_start_sal): Rename to ...
	(find_function_start_sal_1): ... this.
	(find_function_start_sal): Reimplement as wrapper around
	find_function_start_sal_1, and use
	find_pc_sect_containing_function to fill in the sal's symbol.
	(find_function_start_sal(symbol*, bool)): Adjust.
	* symtab.h (find_pc_function, find_pc_sect_function): Adjust
	comments.
	(find_pc_sect_containing_function): Declare.

gdb/testsuite/ChangeLog:
2018-06-29  Pedro Alves  <palves@redhat.com>

	* gdb.opt/inline-break.exp (line number, address): Add "info
	break" tests.
This commit is contained in:
Pedro Alves 2018-06-29 19:31:49 +01:00
parent 991ff2922a
commit cd2bb70994
8 changed files with 83 additions and 12 deletions

View File

@ -1,3 +1,22 @@
2018-06-29 Pedro Alves <palves@redhat.com>
* blockframe.c (find_pc_sect_containing_function): New function.
* breakpoint.c (print_breakpoint_location): Don't call
find_pc_sect_function.
* linespec.c (create_sals_line_offset): Record the location's
symbol in the sal.
* linespec.c (convert_address_location_to_sals): Fill in sal's
symbol with find_pc_sect_containing_function.
* symtab.c (find_function_start_sal): Rename to ...
(find_function_start_sal_1): ... this.
(find_function_start_sal): Reimplement as wrapper around
find_function_start_sal_1, and use
find_pc_sect_containing_function to fill in the sal's symbol.
(find_function_start_sal(symbol*, bool)): Adjust.
* symtab.h (find_pc_function, find_pc_sect_function): Adjust
comments.
(find_pc_sect_containing_function): Declare.
2018-06-29 Pedro Alves <palves@redhat.com>
* inline-frame.c (stopped_by_user_bp_inline_frame): Return

View File

@ -152,6 +152,19 @@ find_pc_function (CORE_ADDR pc)
return find_pc_sect_function (pc, find_pc_mapped_section (pc));
}
/* See symtab.h. */
struct symbol *
find_pc_sect_containing_function (CORE_ADDR pc, struct obj_section *section)
{
const block *bl = block_for_pc_sect (pc, section);
if (bl == nullptr)
return nullptr;
return block_containing_function (bl);
}
/* These variables are used to cache the most recent result
of find_pc_partial_function. */

View File

@ -5867,9 +5867,6 @@ print_breakpoint_location (struct breakpoint *b,
{
const struct symbol *sym = loc->symbol;
if (sym == NULL)
sym = find_pc_sect_function (loc->address, loc->section);
if (sym)
{
uiout->text ("in ");

View File

@ -2196,6 +2196,7 @@ create_sals_line_offset (struct linespec_state *self,
if (self->funfirstline)
skip_prologue_sal (&intermediate_results[i]);
intermediate_results[i].symbol = sym;
add_sal_to_sals (self, &values, &intermediate_results[i],
sym ? SYMBOL_NATURAL_NAME (sym) : NULL, 0);
}
@ -2224,6 +2225,7 @@ convert_address_location_to_sals (struct linespec_state *self,
sal.pc = address;
sal.section = find_pc_overlay (address);
sal.explicit_pc = 1;
sal.symbol = find_pc_sect_containing_function (sal.pc, sal.section);
std::vector<symtab_and_line> sals;
add_sal_to_sals (self, &sals, &sal, core_addr_to_string (address), 1);

View File

@ -3575,11 +3575,12 @@ find_pc_line_pc_range (CORE_ADDR pc, CORE_ADDR *startptr, CORE_ADDR *endptr)
return sal.symtab != 0;
}
/* See symtab.h. */
/* Helper for find_function_start_sal. Does most of the work, except
setting the sal's symbol. */
symtab_and_line
find_function_start_sal (CORE_ADDR func_addr, obj_section *section,
bool funfirstline)
static symtab_and_line
find_function_start_sal_1 (CORE_ADDR func_addr, obj_section *section,
bool funfirstline)
{
symtab_and_line sal = find_pc_sect_line (func_addr, section, 0);
@ -3615,14 +3616,31 @@ find_function_start_sal (CORE_ADDR func_addr, obj_section *section,
/* See symtab.h. */
symtab_and_line
find_function_start_sal (CORE_ADDR func_addr, obj_section *section,
bool funfirstline)
{
symtab_and_line sal
= find_function_start_sal_1 (func_addr, section, funfirstline);
/* find_function_start_sal_1 does a linetable search, so it finds
the symtab and linenumber, but not a symbol. Fill in the
function symbol too. */
sal.symbol = find_pc_sect_containing_function (sal.pc, sal.section);
return sal;
}
/* See symtab.h. */
symtab_and_line
find_function_start_sal (symbol *sym, bool funfirstline)
{
fixup_symbol_section (sym, NULL);
symtab_and_line sal
= find_function_start_sal (BLOCK_START (SYMBOL_BLOCK_VALUE (sym)),
SYMBOL_OBJ_SECTION (symbol_objfile (sym), sym),
funfirstline);
= find_function_start_sal_1 (BLOCK_START (SYMBOL_BLOCK_VALUE (sym)),
SYMBOL_OBJ_SECTION (symbol_objfile (sym), sym),
funfirstline);
sal.symbol = sym;
return sal;
}

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@ -1670,14 +1670,25 @@ extern struct type *lookup_enum (const char *, const struct block *);
/* from blockframe.c: */
/* lookup the function symbol corresponding to the address. */
/* lookup the function symbol corresponding to the address. The
return value will not be an inlined function; the containing
function will be returned instead. */
extern struct symbol *find_pc_function (CORE_ADDR);
/* lookup the function corresponding to the address and section. */
/* lookup the function corresponding to the address and section. The
return value will not be an inlined function; the containing
function will be returned instead. */
extern struct symbol *find_pc_sect_function (CORE_ADDR, struct obj_section *);
/* lookup the function symbol corresponding to the address and
section. The return value will be the closest enclosing function,
which might be an inline function. */
extern struct symbol *find_pc_sect_containing_function
(CORE_ADDR pc, struct obj_section *section);
/* Find the symbol at the given address. Returns NULL if no symbol
found. Only exact matches for ADDRESS are considered. */

View File

@ -1,3 +1,8 @@
2018-06-29 Pedro Alves <palves@redhat.com>
* gdb.opt/inline-break.exp (line number, address): Add "info
break" tests.
2018-06-29 Pedro Alves <palves@redhat.com>
* gdb.opt/inline-break.c (func1): Add "break here" marker.

View File

@ -272,6 +272,9 @@ with_test_prefix "line number" {
# Set the breakpoint by line number, and check that GDB reports
# the breakpoint location being the inline function.
gdb_test "break $srcfile:$line" ".*Breakpoint .* at .*: file .*$srcfile, line $line."
gdb_test "info break \$bpnum" "in func1 at .*$srcfile:$line"
gdb_test "continue" "Breakpoint .*, func1 \\(x=1\\) at .*$srcfile:$line.*break here.*" \
"breakpoint hit presents stop at inlined function"
@ -294,6 +297,9 @@ with_test_prefix "address" {
# Set the breakpoint by address, and check that GDB reports the
# breakpoint location being the inline function.
gdb_test "break *$address" ".*Breakpoint .* at $address: file .*$srcfile, line $line."
gdb_test "info break \$bpnum" "in func1 at .*$srcfile:$line"
gdb_test "continue" "Breakpoint .*, func1 \\(x=1\\) at .*$srcfile:$line.*break here.*" \
"breakpoint hit presents stop at inlined function"
}