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Handle DW_OP_form_tls_address 

Currently gdb supports DW_OP_GNU_push_tls_address, but not
DW_OP_form_tls_address.  I think it would be better if the toolchain
as a whole moved to using the standard opcode, and the prerequisite to
this is getting gdb to recognize it.

GCC can sometimes emit DW_OP_form_tls_address for emultls targets.  As
far as I know, nobody has ever tried this with gdb (since it wouldn't
work at all).

I don't think there's a major drawback to using a single opcode for
all targets, because computing the location of a thread-local is
already target specific.

This is PR gdb/11616.

I don't know how to write a test case for this; though it's worth
noting that there aren't explicit tests for DW_OP_GNU_push_tls_address
either -- and if I change GCC, these paths will be tested to the same
extent they are now.

2016-09-02  Tom Tromey  <tom@tromey.com>

	PR gdb/11616:
	* dwarf2read.c (decode_locdesc): Handle DW_OP_form_tls_address.
	* dwarf2loc.c (dwarf2_compile_expr_to_ax): Handle
	DW_OP_form_tls_address.
	(locexpr_describe_location_piece): Likewise.
	* dwarf2expr.h (struct dwarf_expr_context_funcs): Update comment.
	* dwarf2expr.c (execute_stack_op): Handle DW_OP_form_tls_address.
	(ctx_no_get_tls_address): Mention DW_OP_form_tls_address.
	* compile/compile-loc2c.c (struct insn_info): Update comment.
	(compute_stack_depth_worker): Handle DW_OP_form_tls_address.
This commit is contained in:
Tom Tromey 2016-08-22 16:56:52 -06:00
parent 1b2d85b255
commit 4aa4e28bdc
6 changed files with 26 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
gdb/ChangeLog
View File

@ -1,3 +1,16 @@
2016-09-02 Tom Tromey <tom@tromey.com>
PR gdb/11616:
* dwarf2read.c (decode_locdesc): Handle DW_OP_form_tls_address.
* dwarf2loc.c (dwarf2_compile_expr_to_ax): Handle
DW_OP_form_tls_address.
(locexpr_describe_location_piece): Likewise.
* dwarf2expr.h (struct dwarf_expr_context_funcs): Update comment.
* dwarf2expr.c (execute_stack_op): Handle DW_OP_form_tls_address.
(ctx_no_get_tls_address): Mention DW_OP_form_tls_address.
* compile/compile-loc2c.c (struct insn_info): Update comment.
(compute_stack_depth_worker): Handle DW_OP_form_tls_address.
2016-09-01 Sergio Durigan Junior <sergiodj@redhat.com>
* target.c (target_wait): Mention that the function's prototype

7
gdb/compile/compile-loc2c.c
View File

@ -48,9 +48,9 @@ struct insn_info
unsigned int label : 1;
/* Whether this instruction is DW_OP_GNU_push_tls_address. This is
a hack until we can add a feature to glibc to let us properly
generate code for TLS. */
/* Whether this instruction is DW_OP_GNU_push_tls_address or
DW_OP_form_tls_address. This is a hack until we can add a
feature to glibc to let us properly generate code for TLS. */
unsigned int is_tls : 1;
};
@ -323,6 +323,7 @@ compute_stack_depth_worker (int start, int *need_tempvar,
break;
case DW_OP_GNU_push_tls_address:
case DW_OP_form_tls_address:
info[ndx].is_tls = 1;
break;

3
gdb/dwarf2expr.c
View File

@ -1257,6 +1257,7 @@ execute_stack_op (struct dwarf_expr_context *ctx,
break;
case DW_OP_GNU_push_tls_address:
case DW_OP_form_tls_address:
/* Variable is at a constant offset in the thread-local
storage block into the objfile for the current thread and
the dynamic linker module containing this expression. Here
@ -1533,7 +1534,7 @@ ctx_no_get_frame_pc (void *baton)
CORE_ADDR
ctx_no_get_tls_address (void *baton, CORE_ADDR offset)
{
error (_("%s is invalid in this context"), "DW_OP_GNU_push_tls_address");
error (_("%s is invalid in this context"), "DW_OP_form_tls_address");
}
/* Stub dwarf_expr_context_funcs.dwarf_call implementation. */

2
gdb/dwarf2expr.h
View File

@ -56,7 +56,7 @@ struct dwarf_expr_context_funcs
CORE_ADDR (*get_frame_pc) (void *baton);
/* Return the thread-local storage address for
DW_OP_GNU_push_tls_address. */
DW_OP_GNU_push_tls_address or DW_OP_form_tls_address. */
CORE_ADDR (*get_tls_address) (void *baton, CORE_ADDR offset);
/* Execute DW_AT_location expression for the DWARF expression subroutine in

7
gdb/dwarf2loc.c
View File

@ -3571,6 +3571,7 @@ dwarf2_compile_expr_to_ax (struct agent_expr *expr, struct axs_value *loc,
break;
case DW_OP_GNU_push_tls_address:
case DW_OP_form_tls_address:
unimplemented (op);
break;
@ -3907,7 +3908,8 @@ locexpr_describe_location_piece (struct symbol *symbol, struct ui_file *stream,
&& (data[0] == DW_OP_addr
|| (addr_size == 4 && data[0] == DW_OP_const4u)
|| (addr_size == 8 && data[0] == DW_OP_const8u))
&& data[1 + addr_size] == DW_OP_GNU_push_tls_address
&& (data[1 + addr_size] == DW_OP_GNU_push_tls_address
|| data[1 + addr_size] == DW_OP_form_tls_address)
&& piece_end_p (data + 2 + addr_size, end))
{
ULONGEST offset;
@ -3930,7 +3932,8 @@ locexpr_describe_location_piece (struct symbol *symbol, struct ui_file *stream,
&& data + 1 + (leb128_size = skip_leb128 (data + 1, end)) < end
&& data[0] == DW_OP_GNU_const_index
&& leb128_size > 0
&& data[1 + leb128_size] == DW_OP_GNU_push_tls_address
&& (data[1 + leb128_size] == DW_OP_GNU_push_tls_address
|| data[1 + leb128_size] == DW_OP_form_tls_address)
&& piece_end_p (data + 2 + leb128_size, end))
{
uint64_t offset;

1
gdb/dwarf2read.c
View File

@ -20817,6 +20817,7 @@ decode_locdesc (struct dwarf_block *blk, struct dwarf2_cu *cu)
break;
case DW_OP_GNU_push_tls_address:
case DW_OP_form_tls_address:
/* The top of the stack has the offset from the beginning
of the thread control block at which the variable is located. */
/* Nothing should follow this operator, so the top of stack would