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[RFA] Handle DW_OP_form_tls_address
- From: Tom Tromey <tom at tromey dot com>
- To: gdb-patches at sourceware dot org
- Cc: Tom Tromey <tom at tromey dot com>
- Date: Mon, 22 Aug 2016 17:04:27 -0600
- Subject: [RFA] Handle DW_OP_form_tls_address
- Authentication-results: sourceware.org; auth=none
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.
2016-08-22 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.
---
gdb/ChangeLog | 13 +++++++++++++
gdb/compile/compile-loc2c.c | 7 ++++---
gdb/dwarf2expr.c | 3 ++-
gdb/dwarf2expr.h | 2 +-
gdb/dwarf2loc.c | 7 +++++--
gdb/dwarf2read.c | 1 +
6 files changed, 26 insertions(+), 7 deletions(-)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index db3527b..972a533 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,16 @@
+2016-08-22 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.
+
2016-08-19 Yao Qi <yao.qi@linaro.org>
* aarch64-tdep.c (aarch64_analyze_prologue): Handle register
diff --git a/gdb/compile/compile-loc2c.c b/gdb/compile/compile-loc2c.c
index 1a267b8..e8bef55 100644
--- a/gdb/compile/compile-loc2c.c
+++ b/gdb/compile/compile-loc2c.c
@@ -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;
diff --git a/gdb/dwarf2expr.c b/gdb/dwarf2expr.c
index 7bf3c78..7eb1982 100644
--- a/gdb/dwarf2expr.c
+++ b/gdb/dwarf2expr.c
@@ -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. */
diff --git a/gdb/dwarf2expr.h b/gdb/dwarf2expr.h
index 3d7ca00..cbab45b 100644
--- a/gdb/dwarf2expr.h
+++ b/gdb/dwarf2expr.h
@@ -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
diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c
index e60475f..946ddf8 100644
--- a/gdb/dwarf2loc.c
+++ b/gdb/dwarf2loc.c
@@ -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;
diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 924b417..9ad2caa 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -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
--
2.7.4