/* DWARF 2 location expression support for GDB.
- Copyright 2003 Free Software Foundation, Inc.
+
+ Copyright (C) 2003, 2005, 2007 Free Software Foundation, Inc.
+
Contributed by Daniel Jacobowitz, MontaVista Software, Inc.
This file is part of GDB.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
- Foundation, Inc., 59 Temple Place - Suite 330,
- Boston, MA 02111-1307, USA. */
+ Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ Boston, MA 02110-1301, USA. */
#include "defs.h"
#include "ui-out.h"
#include "gdbcore.h"
#include "target.h"
#include "inferior.h"
+#include "ax.h"
+#include "ax-gdb.h"
+#include "regcache.h"
+#include "objfiles.h"
+#include "exceptions.h"
#include "elf/dwarf2.h"
#include "dwarf2expr.h"
#define DWARF2_REG_TO_REGNUM(REG) (REG)
#endif
+/* A helper function for dealing with location lists. Given a
+ symbol baton (BATON) and a pc value (PC), find the appropriate
+ location expression, set *LOCEXPR_LENGTH, and return a pointer
+ to the beginning of the expression. Returns NULL on failure.
+
+ For now, only return the first matching location expression; there
+ can be more than one in the list. */
+
+static gdb_byte *
+find_location_expression (struct dwarf2_loclist_baton *baton,
+ size_t *locexpr_length, CORE_ADDR pc)
+{
+ CORE_ADDR low, high;
+ gdb_byte *loc_ptr, *buf_end;
+ int length;
+ unsigned int addr_size = TARGET_ADDR_BIT / TARGET_CHAR_BIT;
+ CORE_ADDR base_mask = ~(~(CORE_ADDR)1 << (addr_size * 8 - 1));
+ /* Adjust base_address for relocatable objects. */
+ CORE_ADDR base_offset = ANOFFSET (baton->objfile->section_offsets,
+ SECT_OFF_TEXT (baton->objfile));
+ CORE_ADDR base_address = baton->base_address + base_offset;
+
+ loc_ptr = baton->data;
+ buf_end = baton->data + baton->size;
+
+ while (1)
+ {
+ low = dwarf2_read_address (loc_ptr, buf_end, &length);
+ loc_ptr += length;
+ high = dwarf2_read_address (loc_ptr, buf_end, &length);
+ loc_ptr += length;
+
+ /* An end-of-list entry. */
+ if (low == 0 && high == 0)
+ return NULL;
+
+ /* A base-address-selection entry. */
+ if ((low & base_mask) == base_mask)
+ {
+ base_address = high;
+ continue;
+ }
+
+ /* Otherwise, a location expression entry. */
+ low += base_address;
+ high += base_address;
+
+ length = extract_unsigned_integer (loc_ptr, 2);
+ loc_ptr += 2;
+
+ if (pc >= low && pc < high)
+ {
+ *locexpr_length = length;
+ return loc_ptr;
+ }
+
+ loc_ptr += length;
+ }
+}
+
/* This is the baton used when performing dwarf2 expression
evaluation. */
struct dwarf_expr_baton
/* Helper functions for dwarf2_evaluate_loc_desc. */
-/* Using the frame specified in BATON, read register REGNUM. The lval
- type will be returned in LVALP, and for lval_memory the register
- save address will be returned in ADDRP. */
+/* Using the frame specified in BATON, return the value of register
+ REGNUM, treated as a pointer. */
static CORE_ADDR
-dwarf_expr_read_reg (void *baton, int regnum, enum lval_type *lvalp,
- CORE_ADDR *addrp)
+dwarf_expr_read_reg (void *baton, int dwarf_regnum)
{
- CORE_ADDR result;
struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton;
- char *buf = (char *) alloca (MAX_REGISTER_RAW_SIZE);
- int optimized, realnum;
-
- frame_register (debaton->frame, DWARF2_REG_TO_REGNUM (regnum),
- &optimized, lvalp, addrp, &realnum, buf);
- result = extract_address (buf, REGISTER_RAW_SIZE (regnum));
+ CORE_ADDR result;
+ int regnum;
+ regnum = DWARF2_REG_TO_REGNUM (dwarf_regnum);
+ result = address_from_register (builtin_type_void_data_ptr,
+ regnum, debaton->frame);
return result;
}
/* Read memory at ADDR (length LEN) into BUF. */
static void
-dwarf_expr_read_mem (void *baton, char *buf, CORE_ADDR addr, size_t len)
+dwarf_expr_read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len)
{
read_memory (addr, buf, len);
}
describing the frame base. Return a pointer to it in START and
its length in LENGTH. */
static void
-dwarf_expr_frame_base (void *baton, unsigned char **start, size_t * length)
+dwarf_expr_frame_base (void *baton, gdb_byte **start, size_t * length)
{
+ /* FIXME: cagney/2003-03-26: This code should be using
+ get_frame_base_address(), and then implement a dwarf2 specific
+ this_base method. */
struct symbol *framefunc;
- struct dwarf2_locexpr_baton *symbaton;
struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton;
+
framefunc = get_frame_function (debaton->frame);
- symbaton = SYMBOL_LOCATION_BATON (framefunc);
- *start = symbaton->data;
- *length = symbaton->size;
+
+ if (SYMBOL_OPS (framefunc) == &dwarf2_loclist_funcs)
+ {
+ struct dwarf2_loclist_baton *symbaton;
+ struct frame_info *frame = debaton->frame;
+
+ symbaton = SYMBOL_LOCATION_BATON (framefunc);
+ *start = find_location_expression (symbaton, length,
+ get_frame_address_in_block (frame));
+ }
+ else
+ {
+ struct dwarf2_locexpr_baton *symbaton;
+ symbaton = SYMBOL_LOCATION_BATON (framefunc);
+ *length = symbaton->size;
+ *start = symbaton->data;
+ }
+
+ if (*start == NULL)
+ error (_("Could not find the frame base for \"%s\"."),
+ SYMBOL_NATURAL_NAME (framefunc));
}
/* Using the objfile specified in BATON, find the address for the
dwarf_expr_tls_address (void *baton, CORE_ADDR offset)
{
struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton;
- CORE_ADDR addr;
-
- if (target_get_thread_local_address_p ())
- addr = target_get_thread_local_address (inferior_ptid,
- debaton->objfile,
- offset);
- else
- error ("Cannot find thread-local variables on this target");
- return addr;
+ return target_translate_tls_address (debaton->objfile, offset);
}
/* Evaluate a location description, starting at DATA and with length
of FRAME. */
static struct value *
dwarf2_evaluate_loc_desc (struct symbol *var, struct frame_info *frame,
- unsigned char *data, unsigned short size,
+ gdb_byte *data, unsigned short size,
struct objfile *objfile)
{
- CORE_ADDR result;
+ struct gdbarch *arch = get_frame_arch (frame);
struct value *retval;
struct dwarf_expr_baton baton;
struct dwarf_expr_context *ctx;
+ if (size == 0)
+ {
+ retval = allocate_value (SYMBOL_TYPE (var));
+ VALUE_LVAL (retval) = not_lval;
+ set_value_optimized_out (retval, 1);
+ return retval;
+ }
+
baton.frame = frame;
baton.objfile = objfile;
ctx->get_tls_address = dwarf_expr_tls_address;
dwarf_expr_eval (ctx, data, size);
-
- retval = allocate_value (SYMBOL_TYPE (var));
- VALUE_BFD_SECTION (retval) = SYMBOL_BFD_SECTION (var);
-
- if (ctx->in_reg)
+ if (ctx->num_pieces > 0)
+ {
+ int i;
+ long offset = 0;
+ bfd_byte *contents;
+
+ retval = allocate_value (SYMBOL_TYPE (var));
+ contents = value_contents_raw (retval);
+ for (i = 0; i < ctx->num_pieces; i++)
+ {
+ struct dwarf_expr_piece *p = &ctx->pieces[i];
+ if (p->in_reg)
+ {
+ bfd_byte regval[MAX_REGISTER_SIZE];
+ int gdb_regnum = DWARF2_REG_TO_REGNUM (p->value);
+ get_frame_register (frame, gdb_regnum, regval);
+ memcpy (contents + offset, regval, p->size);
+ }
+ else /* In memory? */
+ {
+ read_memory (p->value, contents + offset, p->size);
+ }
+ offset += p->size;
+ }
+ }
+ else if (ctx->in_reg)
{
- store_unsigned_integer (VALUE_CONTENTS_RAW (retval),
- TYPE_LENGTH (SYMBOL_TYPE (var)),
- dwarf_expr_fetch (ctx, 0));
- VALUE_LVAL (retval) = lval_register;
- VALUE_REGNO (retval) = ctx->regnum;
+ CORE_ADDR dwarf_regnum = dwarf_expr_fetch (ctx, 0);
+ int gdb_regnum = DWARF2_REG_TO_REGNUM (dwarf_regnum);
+ retval = value_from_register (SYMBOL_TYPE (var), gdb_regnum, frame);
}
else
{
- result = dwarf_expr_fetch (ctx, 0);
+ CORE_ADDR address = dwarf_expr_fetch (ctx, 0);
+
+ retval = allocate_value (SYMBOL_TYPE (var));
VALUE_LVAL (retval) = lval_memory;
- VALUE_LAZY (retval) = 1;
- VALUE_ADDRESS (retval) = result;
+ set_value_lazy (retval, 1);
+ VALUE_ADDRESS (retval) = address;
}
free_dwarf_expr_context (ctx);
/* Reads from registers do require a frame. */
static CORE_ADDR
-needs_frame_read_reg (void *baton, int regnum, enum lval_type *lvalp,
- CORE_ADDR *addrp)
+needs_frame_read_reg (void *baton, int regnum)
{
struct needs_frame_baton *nf_baton = baton;
nf_baton->needs_frame = 1;
/* Reads from memory do not require a frame. */
static void
-needs_frame_read_mem (void *baton, char *buf, CORE_ADDR addr, size_t len)
+needs_frame_read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len)
{
memset (buf, 0, len);
}
/* Frame-relative accesses do require a frame. */
static void
-needs_frame_frame_base (void *baton, unsigned char **start, size_t * length)
+needs_frame_frame_base (void *baton, gdb_byte **start, size_t * length)
{
- static char lit0 = DW_OP_lit0;
+ static gdb_byte lit0 = DW_OP_lit0;
struct needs_frame_baton *nf_baton = baton;
*start = &lit0;
requires a frame to evaluate. */
static int
-dwarf2_loc_desc_needs_frame (unsigned char *data, unsigned short size)
+dwarf2_loc_desc_needs_frame (gdb_byte *data, unsigned short size)
{
struct needs_frame_baton baton;
struct dwarf_expr_context *ctx;
+ int in_reg;
baton.needs_frame = 0;
dwarf_expr_eval (ctx, data, size);
+ in_reg = ctx->in_reg;
+
+ if (ctx->num_pieces > 0)
+ {
+ int i;
+
+ /* If the location has several pieces, and any of them are in
+ registers, then we will need a frame to fetch them from. */
+ for (i = 0; i < ctx->num_pieces; i++)
+ if (ctx->pieces[i].in_reg)
+ in_reg = 1;
+ }
+
free_dwarf_expr_context (ctx);
- return baton.needs_frame;
+ return baton.needs_frame || in_reg;
}
+static void
+dwarf2_tracepoint_var_ref (struct symbol *symbol, struct agent_expr *ax,
+ struct axs_value *value, gdb_byte *data,
+ int size)
+{
+ if (size == 0)
+ error (_("Symbol \"%s\" has been optimized out."),
+ SYMBOL_PRINT_NAME (symbol));
+
+ if (size == 1
+ && data[0] >= DW_OP_reg0
+ && data[0] <= DW_OP_reg31)
+ {
+ value->kind = axs_lvalue_register;
+ value->u.reg = data[0] - DW_OP_reg0;
+ }
+ else if (data[0] == DW_OP_regx)
+ {
+ ULONGEST reg;
+ read_uleb128 (data + 1, data + size, ®);
+ value->kind = axs_lvalue_register;
+ value->u.reg = reg;
+ }
+ else if (data[0] == DW_OP_fbreg)
+ {
+ /* And this is worse than just minimal; we should honor the frame base
+ as above. */
+ int frame_reg;
+ LONGEST frame_offset;
+ gdb_byte *buf_end;
+
+ buf_end = read_sleb128 (data + 1, data + size, &frame_offset);
+ if (buf_end != data + size)
+ error (_("Unexpected opcode after DW_OP_fbreg for symbol \"%s\"."),
+ SYMBOL_PRINT_NAME (symbol));
+
+ TARGET_VIRTUAL_FRAME_POINTER (ax->scope, &frame_reg, &frame_offset);
+ ax_reg (ax, frame_reg);
+ ax_const_l (ax, frame_offset);
+ ax_simple (ax, aop_add);
+
+ value->kind = axs_lvalue_memory;
+ }
+ else if (data[0] >= DW_OP_breg0
+ && data[0] <= DW_OP_breg31)
+ {
+ unsigned int reg;
+ LONGEST offset;
+ gdb_byte *buf_end;
+
+ reg = data[0] - DW_OP_breg0;
+ buf_end = read_sleb128 (data + 1, data + size, &offset);
+ if (buf_end != data + size)
+ error (_("Unexpected opcode after DW_OP_breg%u for symbol \"%s\"."),
+ reg, SYMBOL_PRINT_NAME (symbol));
+ ax_reg (ax, reg);
+ ax_const_l (ax, offset);
+ ax_simple (ax, aop_add);
+ value->kind = axs_lvalue_memory;
+ }
+ else
+ error (_("Unsupported DWARF opcode 0x%x in the location of \"%s\"."),
+ data[0], SYMBOL_PRINT_NAME (symbol));
+}
\f
/* Return the value of SYMBOL in FRAME using the DWARF-2 expression
evaluator to calculate the location. */
return 1;
}
+ /* The location expression for a TLS variable looks like this (on a
+ 64-bit LE machine):
+
+ DW_AT_location : 10 byte block: 3 4 0 0 0 0 0 0 0 e0
+ (DW_OP_addr: 4; DW_OP_GNU_push_tls_address)
+
+ 0x3 is the encoding for DW_OP_addr, which has an operand as long
+ as the size of an address on the target machine (here is 8
+ bytes). 0xe0 is the encoding for DW_OP_GNU_push_tls_address.
+ The operand represents the offset at which the variable is within
+ the thread local storage. */
+
+ if (dlbaton->size > 1
+ && dlbaton->data[dlbaton->size - 1] == DW_OP_GNU_push_tls_address)
+ if (dlbaton->data[0] == DW_OP_addr)
+ {
+ int bytes_read;
+ CORE_ADDR offset = dwarf2_read_address (&dlbaton->data[1],
+ &dlbaton->data[dlbaton->size - 1],
+ &bytes_read);
+ fprintf_filtered (stream,
+ "a thread-local variable at offset %s in the "
+ "thread-local storage for `%s'",
+ paddr_nz (offset), dlbaton->objfile->name);
+ return 1;
+ }
+
+
fprintf_filtered (stream,
"a variable with complex or multiple locations (DWARF2)");
return 1;
}
+
+/* Describe the location of SYMBOL as an agent value in VALUE, generating
+ any necessary bytecode in AX.
+
+ NOTE drow/2003-02-26: This function is extremely minimal, because
+ doing it correctly is extremely complicated and there is no
+ publicly available stub with tracepoint support for me to test
+ against. When there is one this function should be revisited. */
+
+static void
+locexpr_tracepoint_var_ref (struct symbol * symbol, struct agent_expr * ax,
+ struct axs_value * value)
+{
+ struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol);
+
+ dwarf2_tracepoint_var_ref (symbol, ax, value, dlbaton->data, dlbaton->size);
+}
+
/* The set of location functions used with the DWARF-2 expression
evaluator. */
-struct location_funcs dwarf2_locexpr_funcs = {
+const struct symbol_ops dwarf2_locexpr_funcs = {
locexpr_read_variable,
locexpr_read_needs_frame,
locexpr_describe_location,
- NULL
+ locexpr_tracepoint_var_ref
+};
+
+
+/* Wrapper functions for location lists. These generally find
+ the appropriate location expression and call something above. */
+
+/* Return the value of SYMBOL in FRAME using the DWARF-2 expression
+ evaluator to calculate the location. */
+static struct value *
+loclist_read_variable (struct symbol *symbol, struct frame_info *frame)
+{
+ struct dwarf2_loclist_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol);
+ struct value *val;
+ gdb_byte *data;
+ size_t size;
+
+ data = find_location_expression (dlbaton, &size,
+ frame ? get_frame_address_in_block (frame)
+ : 0);
+ if (data == NULL)
+ {
+ val = allocate_value (SYMBOL_TYPE (symbol));
+ VALUE_LVAL (val) = not_lval;
+ set_value_optimized_out (val, 1);
+ }
+ else
+ val = dwarf2_evaluate_loc_desc (symbol, frame, data, size,
+ dlbaton->objfile);
+
+ return val;
+}
+
+/* Return non-zero iff we need a frame to evaluate SYMBOL. */
+static int
+loclist_read_needs_frame (struct symbol *symbol)
+{
+ /* If there's a location list, then assume we need to have a frame
+ to choose the appropriate location expression. With tracking of
+ global variables this is not necessarily true, but such tracking
+ is disabled in GCC at the moment until we figure out how to
+ represent it. */
+
+ return 1;
+}
+
+/* Print a natural-language description of SYMBOL to STREAM. */
+static int
+loclist_describe_location (struct symbol *symbol, struct ui_file *stream)
+{
+ /* FIXME: Could print the entire list of locations. */
+ fprintf_filtered (stream, "a variable with multiple locations");
+ return 1;
+}
+
+/* Describe the location of SYMBOL as an agent value in VALUE, generating
+ any necessary bytecode in AX. */
+static void
+loclist_tracepoint_var_ref (struct symbol * symbol, struct agent_expr * ax,
+ struct axs_value * value)
+{
+ struct dwarf2_loclist_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol);
+ gdb_byte *data;
+ size_t size;
+
+ data = find_location_expression (dlbaton, &size, ax->scope);
+ if (data == NULL)
+ error (_("Variable \"%s\" is not available."), SYMBOL_NATURAL_NAME (symbol));
+
+ dwarf2_tracepoint_var_ref (symbol, ax, value, data, size);
+}
+
+/* The set of location functions used with the DWARF-2 expression
+ evaluator and location lists. */
+const struct symbol_ops dwarf2_loclist_funcs = {
+ loclist_read_variable,
+ loclist_read_needs_frame,
+ loclist_describe_location,
+ loclist_tracepoint_var_ref
};
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