[PATCH 05/43] Move compilation unit info to dwarf_expr_context

Zoran Zaric via Gdb-patches
2021-03-01T14:46:58Z

From: Zoran Zaric <zoran.zaric@amd.com>

This patch moves the compilation unit context information and support
from dwarf_expr_executor and dwarf_evaluate_loc_desc to
dwarf_expr_context evaluator. The idea is to report an error when a
given operation requires a compilation unit information to be resolved,
which is not available.

gdb/ChangeLog:

* dwarf2/expr.c (ensure_have_per_cu): New function.
(dwarf_expr_context::dwarf_expr_context): Add compilation unit
context information.
(dwarf_expr_context::get_base_type): Move from
dwarf_evaluate_loc_desc.
(dwarf_expr_context::get_addr_index): Remove method.
(dwarf_expr_context::dwarf_variable_value): Remove method.
(dwarf_expr_context::execute_stack_op): Call compilation unit
context info check. Inline get_addr_index and
dwarf_variable_value methods.
* dwarf2/expr.h (struct dwarf_expr_context): Add compilation
context info. Remove get_addr_index and dwarf_variable_value.
* dwarf2/frame.c (dwarf_expr_executor::get_addr_index): Remove
method.
(dwarf_expr_executor::dwarf_variable_value): Remove method.
* dwarf2/loc.c (sect_variable_value): Expose function.
(dwarf_evaluate_loc_desc::get_addr_index): Remove method.
(dwarf_evaluate_loc_desc::dwarf_variable_value): Remove method.
(class dwarf_evaluate_loc_desc): Move compilation unit context
information to dwarf_expr_context class.
* dwarf2/loc.h (sect_variable_value): Expose function.
---
gdb/dwarf2/expr.c | 55 +++++++++++++++++++++++++++++++++++++++-------
gdb/dwarf2/expr.h | 26 ++++++++--------------
gdb/dwarf2/frame.c | 10 ---------
gdb/dwarf2/loc.c | 35 +++--------------------------
gdb/dwarf2/loc.h | 8 +++++++
5 files changed, 67 insertions(+), 67 deletions(-)

diff --git a/gdb/dwarf2/expr.c b/gdb/dwarf2/expr.c
index 6b5cba6b7b4..5a0a4a4299c 100644
--- a/gdb/dwarf2/expr.c
+++ b/gdb/dwarf2/expr.c
@@ -72,6 +72,20 @@ ensure_have_frame (struct frame_info *frame, const char *op_name)
_("%s evaluation requires a frame."), op_name);
}

+/* Ensure that a PER_CU is defined and throw an exception otherwise.
+
+ Throwing NOT_AVAILABLE_ERROR error so that a client can chose
+ to react differently if the evaluation ended because there
+ was a missing context information. */
+
+static void
+ensure_have_per_cu (struct dwarf2_per_cu_data *per_cu, const char* op_name)
+{
+ if (per_cu == nullptr)
+ throw_error (NOT_AVAILABLE_ERROR,
+ _("%s evaluation requires a compilation unit."), op_name);
+}
+
/* See expr.h. */

CORE_ADDR
@@ -201,6 +215,25 @@ dwarf_expr_context::get_frame_base (const gdb_byte **start,
start, length);
}

+/* See expr.h. */
+
+struct type *
+dwarf_expr_context::get_base_type (cu_offset die_cu_off, int size)
+{
+ if (per_cu == nullptr)
+ return builtin_type (this->gdbarch)->builtin_int;
+
+ struct type *result = dwarf2_get_die_type (die_cu_off, per_cu, per_objfile);
+
+ if (result == NULL)
+ error (_("Could not find type for DW_OP_const_type"));
+
+ if (size != 0 && TYPE_LENGTH (result) != size)
+ error (_("DW_OP_const_type has different sizes for type and data"));
+
+ return result;
+}
+
/* Require that TYPE be an integral type; throw an exception if not. */

static void
@@ -697,14 +730,20 @@ dwarf_expr_context::execute_stack_op (const gdb_byte *op_ptr,

case DW_OP_addrx:
case DW_OP_GNU_addr_index:
+ ensure_have_per_cu (this->per_cu, "DW_OP_addrx");
+
op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
- result = this->get_addr_index (uoffset);
+ result = dwarf2_read_addr_index (this->per_cu, this->per_objfile,
+ uoffset);
result += this->per_objfile->objfile->text_section_offset ();
result_val = value_from_ulongest (address_type, result);
break;
case DW_OP_GNU_const_index:
+ ensure_have_per_cu (per_cu, "DW_OP_GNU_const_index");
+
op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
- result = this->get_addr_index (uoffset);
+ result = dwarf2_read_addr_index (this->per_cu, this->per_objfile,
+ uoffset);
result_val = value_from_ulongest (address_type, result);
break;

@@ -834,10 +873,7 @@ dwarf_expr_context::execute_stack_op (const gdb_byte *op_ptr,
case DW_OP_GNU_implicit_pointer:
{
int64_t len;
-
- if (this->ref_addr_size == -1)
- error (_("DWARF-2 expression error: DW_OP_implicit_pointer "
- "is not allowed in frame context"));
+ ensure_have_per_cu (per_cu, "DW_OP_implicit_pointer");

/* The referred-to DIE of sect_offset kind. */
this->len = extract_unsigned_integer (op_ptr, this->ref_addr_size,
@@ -1330,13 +1366,16 @@ dwarf_expr_context::execute_stack_op (const gdb_byte *op_ptr,

case DW_OP_GNU_variable_value:
{
+ ensure_have_per_cu (per_cu, "DW_OP_GNU_variable_value");
+
sect_offset sect_off
= (sect_offset) extract_unsigned_integer (op_ptr,
this->ref_addr_size,
byte_order);
op_ptr += this->ref_addr_size;
- result_val = value_cast (address_type,
- this->dwarf_variable_value (sect_off));
+ result_val = sect_variable_value (sect_off, this->per_cu,
+ this->per_objfile);
+ result_val = value_cast (address_type, result_val);
}
break;

diff --git a/gdb/dwarf2/expr.h b/gdb/dwarf2/expr.h
index 6ba8efb3cc6..48dd37150db 100644
--- a/gdb/dwarf2/expr.h
+++ b/gdb/dwarf2/expr.h
@@ -189,6 +189,9 @@ struct dwarf_expr_context
/* Frame information used for the evaluation. */
struct frame_info *frame = nullptr;

+ /* Compilation unit used for the evaluation. */
+ struct dwarf2_per_cu_data *per_cu = nullptr;
+
/* Read LENGTH bytes at ADDR into BUF. */
virtual void read_mem (gdb_byte *buf, CORE_ADDR addr, size_t length) = 0;

@@ -208,19 +211,6 @@ struct dwarf_expr_context
subroutine. */
virtual void dwarf_call (cu_offset die_cu_off) = 0;

- /* Execute "variable value" operation on the DIE at SECT_OFF. */
- virtual struct value *dwarf_variable_value (sect_offset sect_off) = 0;
-
- /* Return the base type given by the indicated DIE at DIE_CU_OFF.
- This can throw an exception if the DIE is invalid or does not
- represent a base type. SIZE is non-zero if this function should
- verify that the resulting type has the correct size. */
- virtual struct type *get_base_type (cu_offset die_cu_off, int size)
- {
- /* Anything will do. */
- return builtin_type (this->gdbarch)->builtin_int;
- }
-
/* Push on DWARF stack an entry evaluated for DW_TAG_call_site's
parameter matching KIND and KIND_U at the caller of specified BATON.
If DEREF_SIZE is not -1 then use DW_AT_call_data_value instead of
@@ -229,10 +219,6 @@ struct dwarf_expr_context
union call_site_parameter_u kind_u,
int deref_size) = 0;

- /* Return the address indexed by DW_OP_addrx or DW_OP_GNU_addr_index.
- This can throw an exception if the index is out of range. */
- virtual CORE_ADDR get_addr_index (unsigned int index) = 0;
-
/* Return the `object address' for DW_OP_push_object_address. */
virtual CORE_ADDR get_object_address () = 0;

@@ -255,6 +241,12 @@ struct dwarf_expr_context
START and LENGTH. The result must be live until the current
expression evaluation is complete. */
void get_frame_base (const gdb_byte **start, size_t *length);
+
+ /* Return the base type given by the indicated DIE at DIE_CU_OFF.
+ This can throw an exception if the DIE is invalid or does not
+ represent a base type. SIZE is non-zero if this function should
+ verify that the resulting type has the correct size. */
+ struct type *get_base_type (cu_offset die_cu_off, int size);
};

/* Return the value of register number REG (a DWARF register number),
diff --git a/gdb/dwarf2/frame.c b/gdb/dwarf2/frame.c
index 682f2881556..69a3e424c6e 100644
--- a/gdb/dwarf2/frame.c
+++ b/gdb/dwarf2/frame.c
@@ -258,16 +258,6 @@ class dwarf_expr_executor : public dwarf_expr_context
invalid ("DW_OP_call*");
}

- struct value *dwarf_variable_value (sect_offset sect_off) override
- {
- invalid ("DW_OP_GNU_variable_value");
- }
-
- CORE_ADDR get_addr_index (unsigned int index) override
- {
- invalid ("DW_OP_addrx or DW_OP_GNU_addr_index");
- }
-
private:

void invalid (const char *op) ATTRIBUTE_NORETURN
diff --git a/gdb/dwarf2/loc.c b/gdb/dwarf2/loc.c
index 2ad262dc802..1281a8a3d34 100644
--- a/gdb/dwarf2/loc.c
+++ b/gdb/dwarf2/loc.c
@@ -620,12 +620,10 @@ per_cu_dwarf_call (struct dwarf_expr_context *ctx, cu_offset die_offset,
ctx->eval (block.data, block.size);
}

-/* Given context CTX, section offset SECT_OFF, and compilation unit
- data PER_CU, execute the "variable value" operation on the DIE
- found at SECT_OFF. */
+/* See loc.h. */

-static struct value *
-sect_variable_value (struct dwarf_expr_context *ctx, sect_offset sect_off,
+struct value *
+sect_variable_value (sect_offset sect_off,
dwarf2_per_cu_data *per_cu,
dwarf2_per_objfile *per_objfile)
{
@@ -654,7 +652,6 @@ class dwarf_evaluate_loc_desc : public dwarf_expr_context
: dwarf_expr_context (per_objfile)
{}

- struct dwarf2_per_cu_data *per_cu;
CORE_ADDR obj_address;

/* Helper function for dwarf2_evaluate_loc_desc. Computes the PC for
@@ -680,32 +677,6 @@ class dwarf_evaluate_loc_desc : public dwarf_expr_context
per_cu_dwarf_call (this, die_offset, per_cu, per_objfile);
}

- /* Helper interface of sect_variable_value for
- dwarf2_evaluate_loc_desc. */
-
- struct value *dwarf_variable_value (sect_offset sect_off) override
- {
- return sect_variable_value (this, sect_off, per_cu, per_objfile);
- }
-
- struct type *get_base_type (cu_offset die_offset, int size) override
- {
- struct type *result = dwarf2_get_die_type (die_offset, per_cu, per_objfile);
- if (result == NULL)
- error (_("Could not find type for DW_OP_const_type"));
- if (size != 0 && TYPE_LENGTH (result) != size)
- error (_("DW_OP_const_type has different sizes for type and data"));
- return result;
- }
-
- /* Callback function for dwarf2_evaluate_loc_desc.
- Fetch the address indexed by DW_OP_addrx or DW_OP_GNU_addr_index. */
-
- CORE_ADDR get_addr_index (unsigned int index) override
- {
- return dwarf2_read_addr_index (per_cu, per_objfile, index);
- }
-
/* Callback function for get_object_address. Return the address of the VLA
object. */

diff --git a/gdb/dwarf2/loc.h b/gdb/dwarf2/loc.h
index 2943baf91d2..a729b370e2e 100644
--- a/gdb/dwarf2/loc.h
+++ b/gdb/dwarf2/loc.h
@@ -53,6 +53,14 @@ extern void func_get_frame_base_dwarf_block (struct symbol *framefunc,
const gdb_byte **start,
size_t *length);

+/* Given section offset SECT_OFF, and compilation unit data
+ PER_CU, execute the "variable value" operation on the DIE
+ found at SECT_OFF. */
+
+struct value *sect_variable_value (sect_offset sect_off,
+ dwarf2_per_cu_data *per_cu,
+ dwarf2_per_objfile *per_objfile);
+
/* Evaluate a location description, starting at DATA and with length
SIZE, to find the current location of variable of TYPE in the context
of FRAME. */
--
2.17.1