From: Zoran Zaric <zoran.zaric@amd.com>
To: <gdb-patches@sourceware.org>
Subject: [PATCH v4 23/28] Add support for any location description in CFI
Date: Fri, 5 Nov 2021 11:38:44 +0000 [thread overview]
Message-ID: <20211105113849.118800-24-zoran.zaric@amd.com> (raw)
In-Reply-To: <20211105113849.118800-1-zoran.zaric@amd.com>
From: Zoran Zaric <Zoran.Zaric@amd.com>
One of the main benefits of allowing location description to be on the
DWARF stack is that now CFI expression based register rules can be
defined using a location description operations. This allows a register
of one frame to be saved in any location, including any composite
location.
To fully support this feature, the execute_stack_op function in
dwarf2/frame.c needs to return a single struct value object instead of
just an address.
Function put_frame_register_bytes also needs to change to support any
location description.
This support is a one of the key features to truly support optimized
code.
gdb/ChangeLog:
* dwarf2/frame.c (execute_stack_op): Change to return a struct
value object.
(dwarf2_frame_cache): Change to call new execute_stack_op
definition.
(dwarf2_frame_prev_register): Change to call new execute_stack_op
definition.
* frame.c (put_frame_register_bytes): Add support for writing to
composite location description.
---
gdb/dwarf2/frame.c | 54 ++++++++++++++++++++++++++--------------------
gdb/frame.c | 31 ++++++++++++++++++++++----
2 files changed, 58 insertions(+), 27 deletions(-)
diff --git a/gdb/dwarf2/frame.c b/gdb/dwarf2/frame.c
index e17b36e243b..e70dcd5a86e 100644
--- a/gdb/dwarf2/frame.c
+++ b/gdb/dwarf2/frame.c
@@ -236,16 +236,17 @@ register %s (#%d) at %s"),
}
}
-static CORE_ADDR
+static value *
execute_stack_op (const gdb_byte *exp, ULONGEST len, int addr_size,
struct frame_info *this_frame, CORE_ADDR initial,
- int initial_in_stack_memory, dwarf2_per_objfile *per_objfile)
+ int initial_in_stack_memory, dwarf2_per_objfile *per_objfile,
+ struct type* type = nullptr, bool as_lval = true)
{
scoped_value_mark free_values;
- struct type *type = address_type (per_objfile->objfile->arch (),
- addr_size);
+ struct type *init_type = address_type (per_objfile->objfile->arch (),
+ addr_size);
- value *init_value = value_at_lazy (type, initial);
+ value *init_value = value_at_lazy (init_type, initial);
std::vector<value *> init_values;
set_value_stack (init_value, initial_in_stack_memory);
@@ -255,10 +256,15 @@ execute_stack_op (const gdb_byte *exp, ULONGEST len, int addr_size,
= dwarf2_evaluate (exp, len, true, per_objfile, nullptr,
this_frame, addr_size, &init_values, nullptr);
- if (VALUE_LVAL (result_val) == lval_memory)
- return value_address (result_val);
- else
- return value_as_address (result_val);
+ /* We need to clean up all the values that are not needed any more.
+ The problem with a value_ref_ptr class is that it disconnects the
+ RETVAL from the value garbage collection, so we need to make
+ a copy of that value on the stack to keep everything consistent.
+ The value_ref_ptr will clean up after itself at the end of this block. */
+ value_ref_ptr value_holder = value_ref_ptr::new_reference (result_val);
+ free_values.free_to_mark ();
+
+ return value_copy (result_val);
}
\f
@@ -989,10 +995,14 @@ dwarf2_frame_cache (struct frame_info *this_frame, void **this_cache)
break;
case CFA_EXP:
- cache->cfa =
- execute_stack_op (fs.regs.cfa_exp, fs.regs.cfa_exp_len,
- cache->addr_size, this_frame, 0, 0,
- cache->per_objfile);
+ {
+ struct value *value
+ = execute_stack_op (fs.regs.cfa_exp, fs.regs.cfa_exp_len,
+ cache->addr_size, this_frame, 0, 0,
+ cache->per_objfile);
+ cache->cfa = value_address (value);
+ }
+
break;
default:
@@ -1190,24 +1200,22 @@ dwarf2_frame_prev_register (struct frame_info *this_frame, void **this_cache,
return frame_unwind_got_register (this_frame, regnum, realnum);
case DWARF2_FRAME_REG_SAVED_EXP:
- addr = execute_stack_op (cache->reg[regnum].loc.exp.start,
+ return execute_stack_op (cache->reg[regnum].loc.exp.start,
cache->reg[regnum].loc.exp.len,
- cache->addr_size,
- this_frame, cache->cfa, 1,
- cache->per_objfile);
- return frame_unwind_got_memory (this_frame, regnum, addr);
+ cache->addr_size, this_frame,
+ cache->cfa, 1, cache->per_objfile,
+ register_type (gdbarch, regnum));
case DWARF2_FRAME_REG_SAVED_VAL_OFFSET:
addr = cache->cfa + cache->reg[regnum].loc.offset;
return frame_unwind_got_constant (this_frame, regnum, addr);
case DWARF2_FRAME_REG_SAVED_VAL_EXP:
- addr = execute_stack_op (cache->reg[regnum].loc.exp.start,
+ return execute_stack_op (cache->reg[regnum].loc.exp.start,
cache->reg[regnum].loc.exp.len,
- cache->addr_size,
- this_frame, cache->cfa, 1,
- cache->per_objfile);
- return frame_unwind_got_constant (this_frame, regnum, addr);
+ cache->addr_size, this_frame,
+ cache->cfa, 1, cache->per_objfile,
+ register_type (gdbarch, regnum), false);
case DWARF2_FRAME_REG_UNSPECIFIED:
/* GCC, in its infinite wisdom decided to not provide unwind
diff --git a/gdb/frame.c b/gdb/frame.c
index 2a899fc494f..3dd6c799847 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -1534,19 +1534,42 @@ put_frame_register_bytes (struct frame_info *frame, int regnum,
{
int curr_len = register_size (gdbarch, regnum) - offset;
+ struct value *value = frame_unwind_register_value (frame->next,
+ regnum);
+
if (curr_len > len)
curr_len = len;
const gdb_byte *myaddr = buffer.data ();
- if (curr_len == register_size (gdbarch, regnum))
+
+ /* Computed value is a special case. The computed callback
+ mechanism requires a strut value argument, so we need to
+ make one. */
+ if (value != nullptr && VALUE_LVAL (value) == lval_computed)
+ {
+ const lval_funcs *funcs = value_computed_funcs (value);
+
+ if (funcs->write == nullptr)
+ error (_("Attempt to assign to an unmodifiable value."));
+
+ type * reg_type = register_type (gdbarch, regnum);
+
+ struct value *from_value = allocate_value (reg_type);
+ memcpy (value_contents_raw (from_value), myaddr,
+ TYPE_LENGTH (reg_type));
+
+ set_value_offset (value, offset);
+
+ funcs->write (value, from_value);
+ release_value (from_value);
+ }
+ else if (curr_len == register_size (gdbarch, regnum))
{
put_frame_register (frame, regnum, myaddr);
}
else
{
- struct value *value = frame_unwind_register_value (frame->next,
- regnum);
- gdb_assert (value != NULL);
+ gdb_assert (value != nullptr);
memcpy ((char *) value_contents_writeable (value).data () + offset,
myaddr, curr_len);
--
2.17.1
next prev parent reply other threads:[~2021-11-05 11:39 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-05 11:38 [PATCH v4 00/28] Allow location description on the DWARF stack Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 01/28] Add new register access interface to expr.c Zoran Zaric
2021-12-14 20:34 ` Tom Tromey
2021-11-05 11:38 ` [PATCH v4 02/28] Add new memory " Zoran Zaric
2021-12-14 20:42 ` Tom Tromey
2021-11-05 11:38 ` [PATCH v4 03/28] Add new classes that model DWARF stack element Zoran Zaric
2021-12-14 21:10 ` Tom Tromey
2022-01-12 10:23 ` Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 04/28] Add to_location method to dwarf_value class Zoran Zaric
2021-12-14 21:16 ` Tom Tromey
2022-01-12 10:51 ` Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 05/28] Add to_value method to dwarf_location class Zoran Zaric
2021-12-14 21:34 ` Tom Tromey
2022-01-12 12:14 ` Zoran Zaric
2022-01-12 18:42 ` Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 06/28] Add read method to location description classes Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 07/28] Add write " Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 08/28] Add deref " Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 09/28] Add read_from_gdb_value method to dwarf_location Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 10/28] Add write_to_gdb_value " Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 11/28] Add is_implicit_ptr_at " Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 12/28] Add indirect_implicit_ptr to dwarf_location class Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 13/28] Add is_optimized_out " Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 14/28] Add new computed struct value callback interface Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 15/28] Add to_gdb_value method to DWARF entry class Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 16/28] Change DWARF stack to use new dwarf_entry classes Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 17/28] Remove old computed struct value callbacks Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 18/28] Comments cleanup between expr.h and expr.c Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 19/28] Remove dwarf_expr_context from expr.h interface Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 20/28] Move read_addr_from_reg function to frame.c Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 21/28] Add frame info check to DW_OP_reg operations Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 22/28] Remove DWARF expression composition check Zoran Zaric
2021-11-05 11:38 ` Zoran Zaric [this message]
2021-11-05 11:38 ` [PATCH v4 24/28] Add DWARF operations for byte and bit offset Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 25/28] Add support for DW_OP_LLVM_undefined operation Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 26/28] Add support for nested composite locations Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 27/28] Add DW_OP_LLVM_extend DWARF operation Zoran Zaric
2021-11-05 11:38 ` [PATCH v4 28/28] Add DW_OP_LLVM_select_bit_piece " Zoran Zaric
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