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binutils-gdb/gdb/dwarf2expr.c

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Based on a patch from Daniel Berlin (dberlin@dberlin.org). * symtab.h: Add opaque declarations of struct axs_value and struct agent_expr. (enum address_class): Add LOC_COMPUTED and LOC_COMPUTED_ARG. (struct location_funcs): New type. (struct symbol): Add "loc" to aux_value. (SYMBOL_LOCATION_BATON, SYMBOL_LOCATION_FUNCS): New macros. * dwarf2read.c: Include "dwarf2expr.h". (dwarf2_symbol_mark_computed): New function. (read_func_scope): Use it. (var_decode_location): New function. (new_symbol): Use it. * dwarf2expr.c, dwarf2expr.h, dwarf2loc.c, dwarf2loc.h: New files. * Makefile.in (SFILES): Add dwarf2loc.c and dwarf2expr.c. (dwarf2expr_h, dwarf2loc_h): New variables. (COMMON_OBS): Add dwarf2expr.o and dwarf2loc.o. (dwarf2expr.o, dwarf2loc.o): New rules. (dwarf2read.o): Add $(dwarf2expr_h) and $(dwarf2loc_h). * buildsym.c (finish_block): Handle LOC_COMPUTED and LOC_COMPUTED_ARG. * findvar.c (symbol_read_needs_frame, read_var_value): Likewise. * m2-exp.y (yylex): Likewise. * printcmd.c (address_info, print_frame_args): Likewise. * stack.c (print_block_frame_locals, print_frame_arg_vars): Likewise. * symmisc.c (print_symbol, print_partial_symbols): Likewise. * ada-lang.c (ada_resolve_subexp, symtab_for_sym) (ada_add_block_symbols, fill_in_ada_prototype): Likewise. * symtab.c (lookup_block_symbol): Likewise.
2003-02-21 16:24:18 +01:00
/* Dwarf2 Expression Evaluator
Copyright 2001, 2002, 2003 Free Software Foundation, Inc.
Contributed by Daniel Berlin (dan@dberlin.org)
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
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. */
#include "defs.h"
#include "symtab.h"
#include "gdbtypes.h"
#include "value.h"
#include "gdbcore.h"
#include "elf/dwarf2.h"
#include "dwarf2expr.h"
/* Local prototypes. */
static void execute_stack_op (struct dwarf_expr_context *,
unsigned char *, unsigned char *);
/* Create a new context for the expression evaluator. */
struct dwarf_expr_context *
new_dwarf_expr_context ()
{
struct dwarf_expr_context *retval;
retval = xcalloc (1, sizeof (struct dwarf_expr_context));
retval->stack_len = 10;
retval->stack = xmalloc (10 * sizeof (CORE_ADDR));
return retval;
}
/* Release the memory allocated to CTX. */
void
free_dwarf_expr_context (struct dwarf_expr_context *ctx)
{
xfree (ctx->stack);
xfree (ctx);
}
/* Expand the memory allocated to CTX's stack to contain at least
NEED more elements than are currently used. */
static void
dwarf_expr_grow_stack (struct dwarf_expr_context *ctx, size_t need)
{
if (ctx->stack_len + need > ctx->stack_allocated)
{
size_t templen = ctx->stack_len * 2;
while (templen < (ctx->stack_len + need))
templen *= 2;
ctx->stack = xrealloc (ctx->stack,
templen * sizeof (CORE_ADDR));
ctx->stack_allocated = templen;
}
}
/* Push VALUE onto CTX's stack. */
void
dwarf_expr_push (struct dwarf_expr_context *ctx, CORE_ADDR value)
{
dwarf_expr_grow_stack (ctx, 1);
ctx->stack[ctx->stack_len++] = value;
}
/* Pop the top item off of CTX's stack. */
void
dwarf_expr_pop (struct dwarf_expr_context *ctx)
{
if (ctx->stack_len <= 0)
error ("dwarf expression stack underflow");
ctx->stack_len--;
}
/* Retrieve the N'th item on CTX's stack. */
CORE_ADDR
dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n)
{
if (ctx->stack_len < n)
error ("Asked for position %d of stack, stack only has %d elements on it\n",
n, ctx->stack_len);
return ctx->stack[ctx->stack_len - (1 + n)];
}
/* Evaluate the expression at ADDR (LEN bytes long) using the context
CTX. */
void
dwarf_expr_eval (struct dwarf_expr_context *ctx, unsigned char *addr,
size_t len)
{
execute_stack_op (ctx, addr, addr + len);
}
/* Decode the unsigned LEB128 constant at BUF into the variable pointed to
by R, and return the new value of BUF. Verify that it doesn't extend
past BUF_END. */
static unsigned char *
read_uleb128 (unsigned char *buf, unsigned char *buf_end, ULONGEST * r)
{
unsigned shift = 0;
ULONGEST result = 0;
unsigned char byte;
while (1)
{
if (buf >= buf_end)
error ("read_uleb128: Corrupted DWARF expression.");
byte = *buf++;
result |= (byte & 0x7f) << shift;
if ((byte & 0x80) == 0)
break;
shift += 7;
}
*r = result;
return buf;
}
/* Decode the signed LEB128 constant at BUF into the variable pointed to
by R, and return the new value of BUF. Verify that it doesn't extend
past BUF_END. */
static unsigned char *
read_sleb128 (unsigned char *buf, unsigned char *buf_end, LONGEST * r)
{
unsigned shift = 0;
LONGEST result = 0;
unsigned char byte;
while (1)
{
if (buf >= buf_end)
error ("read_sleb128: Corrupted DWARF expression.");
byte = *buf++;
result |= (byte & 0x7f) << shift;
shift += 7;
if ((byte & 0x80) == 0)
break;
}
if (shift < (sizeof (*r) * 8) && (byte & 0x40) != 0)
result |= -(1 << shift);
*r = result;
return buf;
}
/* Read an address from BUF, and verify that it doesn't extend past
BUF_END. The address is returned, and *BYTES_READ is set to the
number of bytes read from BUF. */
static CORE_ADDR
read_address (unsigned char *buf, unsigned char *buf_end, int *bytes_read)
{
CORE_ADDR result;
if (buf_end - buf < TARGET_ADDR_BIT / TARGET_CHAR_BIT)
error ("read_address: Corrupted DWARF expression.");
*bytes_read = TARGET_ADDR_BIT / TARGET_CHAR_BIT;
result = extract_address (buf, TARGET_ADDR_BIT / TARGET_CHAR_BIT);
return result;
}
/* Return the type of an address, for unsigned arithmetic. */
static struct type *
unsigned_address_type (void)
{
switch (TARGET_ADDR_BIT / TARGET_CHAR_BIT)
{
case 2:
return builtin_type_uint16;
case 4:
return builtin_type_uint32;
case 8:
return builtin_type_uint64;
default:
internal_error (__FILE__, __LINE__,
"Unsupported address size.\n");
}
}
/* Return the type of an address, for signed arithmetic. */
static struct type *
signed_address_type (void)
{
switch (TARGET_ADDR_BIT / TARGET_CHAR_BIT)
{
case 2:
return builtin_type_int16;
case 4:
return builtin_type_int32;
case 8:
return builtin_type_int64;
default:
internal_error (__FILE__, __LINE__,
"Unsupported address size.\n");
}
}
/* The engine for the expression evaluator. Using the context in CTX,
evaluate the expression between OP_PTR and OP_END. */
static void
execute_stack_op (struct dwarf_expr_context *ctx, unsigned char *op_ptr,
unsigned char *op_end)
{
while (op_ptr < op_end)
{
enum dwarf_location_atom op = *op_ptr++;
CORE_ADDR result, memaddr;
ULONGEST uoffset, reg;
LONGEST offset;
int bytes_read;
enum lval_type expr_lval;
ctx->in_reg = 0;
switch (op)
{
case DW_OP_lit0:
case DW_OP_lit1:
case DW_OP_lit2:
case DW_OP_lit3:
case DW_OP_lit4:
case DW_OP_lit5:
case DW_OP_lit6:
case DW_OP_lit7:
case DW_OP_lit8:
case DW_OP_lit9:
case DW_OP_lit10:
case DW_OP_lit11:
case DW_OP_lit12:
case DW_OP_lit13:
case DW_OP_lit14:
case DW_OP_lit15:
case DW_OP_lit16:
case DW_OP_lit17:
case DW_OP_lit18:
case DW_OP_lit19:
case DW_OP_lit20:
case DW_OP_lit21:
case DW_OP_lit22:
case DW_OP_lit23:
case DW_OP_lit24:
case DW_OP_lit25:
case DW_OP_lit26:
case DW_OP_lit27:
case DW_OP_lit28:
case DW_OP_lit29:
case DW_OP_lit30:
case DW_OP_lit31:
result = op - DW_OP_lit0;
break;
case DW_OP_addr:
result = read_address (op_ptr, op_end, &bytes_read);
op_ptr += bytes_read;
break;
case DW_OP_const1u:
result = extract_unsigned_integer (op_ptr, 1);
op_ptr += 1;
break;
case DW_OP_const1s:
result = extract_signed_integer (op_ptr, 1);
op_ptr += 1;
break;
case DW_OP_const2u:
result = extract_unsigned_integer (op_ptr, 2);
op_ptr += 2;
break;
case DW_OP_const2s:
result = extract_signed_integer (op_ptr, 2);
op_ptr += 2;
break;
case DW_OP_const4u:
result = extract_unsigned_integer (op_ptr, 4);
op_ptr += 4;
break;
case DW_OP_const4s:
result = extract_signed_integer (op_ptr, 4);
op_ptr += 4;
break;
case DW_OP_const8u:
result = extract_unsigned_integer (op_ptr, 8);
op_ptr += 8;
break;
case DW_OP_const8s:
result = extract_signed_integer (op_ptr, 8);
op_ptr += 8;
break;
case DW_OP_constu:
op_ptr = read_uleb128 (op_ptr, op_end, &uoffset);
result = uoffset;
break;
case DW_OP_consts:
op_ptr = read_sleb128 (op_ptr, op_end, &offset);
result = offset;
break;
/* The DW_OP_reg operations are required to occur alone in
location expressions. */
case DW_OP_reg0:
case DW_OP_reg1:
case DW_OP_reg2:
case DW_OP_reg3:
case DW_OP_reg4:
case DW_OP_reg5:
case DW_OP_reg6:
case DW_OP_reg7:
case DW_OP_reg8:
case DW_OP_reg9:
case DW_OP_reg10:
case DW_OP_reg11:
case DW_OP_reg12:
case DW_OP_reg13:
case DW_OP_reg14:
case DW_OP_reg15:
case DW_OP_reg16:
case DW_OP_reg17:
case DW_OP_reg18:
case DW_OP_reg19:
case DW_OP_reg20:
case DW_OP_reg21:
case DW_OP_reg22:
case DW_OP_reg23:
case DW_OP_reg24:
case DW_OP_reg25:
case DW_OP_reg26:
case DW_OP_reg27:
case DW_OP_reg28:
case DW_OP_reg29:
case DW_OP_reg30:
case DW_OP_reg31:
/* NOTE: in the presence of DW_OP_piece this check is incorrect. */
if (op_ptr != op_end)
error ("DWARF-2 expression error: DW_OP_reg operations must be "
"used alone.");
/* FIXME drow/2003-02-21: This call to read_reg could be pushed
into the evaluator's caller by changing the semantics for in_reg.
Then we wouldn't need to return an lval_type and a memaddr. */
result = (ctx->read_reg) (ctx->baton, op - DW_OP_reg0, &expr_lval,
&memaddr);
if (expr_lval == lval_register)
{
ctx->regnum = op - DW_OP_reg0;
ctx->in_reg = 1;
}
else
result = memaddr;
break;
case DW_OP_regx:
op_ptr = read_uleb128 (op_ptr, op_end, &reg);
if (op_ptr != op_end)
error ("DWARF-2 expression error: DW_OP_reg operations must be "
"used alone.");
result = (ctx->read_reg) (ctx->baton, reg, &expr_lval, &memaddr);
if (expr_lval == lval_register)
{
ctx->regnum = reg;
ctx->in_reg = 1;
}
else
result = memaddr;
break;
case DW_OP_breg0:
case DW_OP_breg1:
case DW_OP_breg2:
case DW_OP_breg3:
case DW_OP_breg4:
case DW_OP_breg5:
case DW_OP_breg6:
case DW_OP_breg7:
case DW_OP_breg8:
case DW_OP_breg9:
case DW_OP_breg10:
case DW_OP_breg11:
case DW_OP_breg12:
case DW_OP_breg13:
case DW_OP_breg14:
case DW_OP_breg15:
case DW_OP_breg16:
case DW_OP_breg17:
case DW_OP_breg18:
case DW_OP_breg19:
case DW_OP_breg20:
case DW_OP_breg21:
case DW_OP_breg22:
case DW_OP_breg23:
case DW_OP_breg24:
case DW_OP_breg25:
case DW_OP_breg26:
case DW_OP_breg27:
case DW_OP_breg28:
case DW_OP_breg29:
case DW_OP_breg30:
case DW_OP_breg31:
{
op_ptr = read_sleb128 (op_ptr, op_end, &offset);
result = (ctx->read_reg) (ctx->baton, op - DW_OP_breg0,
&expr_lval, &memaddr);
result += offset;
}
break;
case DW_OP_bregx:
{
op_ptr = read_uleb128 (op_ptr, op_end, &reg);
op_ptr = read_sleb128 (op_ptr, op_end, &offset);
result = (ctx->read_reg) (ctx->baton, reg, &expr_lval, &memaddr);
result += offset;
}
break;
case DW_OP_fbreg:
{
unsigned char *datastart;
size_t datalen;
unsigned int before_stack_len;
op_ptr = read_sleb128 (op_ptr, op_end, &offset);
/* Rather than create a whole new context, we simply
record the stack length before execution, then reset it
afterwards, effectively erasing whatever the recursive
call put there. */
before_stack_len = ctx->stack_len;
(ctx->get_frame_base) (ctx->baton, &datastart, &datalen);
dwarf_expr_eval (ctx, datastart, datalen);
result = dwarf_expr_fetch (ctx, 0);
if (! ctx->in_reg)
{
char *buf = alloca (TARGET_ADDR_BIT / TARGET_CHAR_BIT);
int bytes_read;
(ctx->read_mem) (ctx->baton, buf, result,
TARGET_ADDR_BIT / TARGET_CHAR_BIT);
result = read_address (buf,
buf + TARGET_ADDR_BIT / TARGET_CHAR_BIT,
&bytes_read);
}
result = result + offset;
ctx->stack_len = before_stack_len;
ctx->in_reg = 0;
}
break;
case DW_OP_dup:
result = dwarf_expr_fetch (ctx, 0);
break;
case DW_OP_drop:
dwarf_expr_pop (ctx);
goto no_push;
case DW_OP_pick:
offset = *op_ptr++;
result = dwarf_expr_fetch (ctx, offset);
break;
case DW_OP_over:
result = dwarf_expr_fetch (ctx, 1);
break;
case DW_OP_rot:
{
CORE_ADDR t1, t2, t3;
if (ctx->stack_len < 3)
error ("Not enough elements for DW_OP_rot. Need 3, have %d\n",
ctx->stack_len);
t1 = ctx->stack[ctx->stack_len - 1];
t2 = ctx->stack[ctx->stack_len - 2];
t3 = ctx->stack[ctx->stack_len - 3];
ctx->stack[ctx->stack_len - 1] = t2;
ctx->stack[ctx->stack_len - 2] = t3;
ctx->stack[ctx->stack_len - 3] = t1;
goto no_push;
}
case DW_OP_deref:
case DW_OP_deref_size:
case DW_OP_abs:
case DW_OP_neg:
case DW_OP_not:
case DW_OP_plus_uconst:
/* Unary operations. */
result = dwarf_expr_fetch (ctx, 0);
dwarf_expr_pop (ctx);
switch (op)
{
case DW_OP_deref:
{
char *buf = alloca (TARGET_ADDR_BIT / TARGET_CHAR_BIT);
int bytes_read;
(ctx->read_mem) (ctx->baton, buf, result,
TARGET_ADDR_BIT / TARGET_CHAR_BIT);
result = read_address (buf,
buf + TARGET_ADDR_BIT / TARGET_CHAR_BIT,
&bytes_read);
}
break;
case DW_OP_deref_size:
{
char *buf = alloca (TARGET_ADDR_BIT / TARGET_CHAR_BIT);
int bytes_read;
(ctx->read_mem) (ctx->baton, buf, result, *op_ptr++);
result = read_address (buf,
buf + TARGET_ADDR_BIT / TARGET_CHAR_BIT,
&bytes_read);
}
break;
case DW_OP_abs:
if ((signed int) result < 0)
result = -result;
break;
case DW_OP_neg:
result = -result;
break;
case DW_OP_not:
result = ~result;
break;
case DW_OP_plus_uconst:
op_ptr = read_uleb128 (op_ptr, op_end, &reg);
result += reg;
break;
}
break;
case DW_OP_and:
case DW_OP_div:
case DW_OP_minus:
case DW_OP_mod:
case DW_OP_mul:
case DW_OP_or:
case DW_OP_plus:
case DW_OP_shl:
case DW_OP_shr:
case DW_OP_shra:
case DW_OP_xor:
case DW_OP_le:
case DW_OP_ge:
case DW_OP_eq:
case DW_OP_lt:
case DW_OP_gt:
case DW_OP_ne:
{
/* Binary operations. Use the value engine to do computations in
the right width. */
CORE_ADDR first, second;
enum exp_opcode binop;
struct value *val1, *val2;
second = dwarf_expr_fetch (ctx, 0);
dwarf_expr_pop (ctx);
first = dwarf_expr_fetch (ctx, 1);
dwarf_expr_pop (ctx);
val1 = value_from_longest (unsigned_address_type (), first);
val2 = value_from_longest (unsigned_address_type (), second);
switch (op)
{
case DW_OP_and:
binop = BINOP_BITWISE_AND;
break;
case DW_OP_div:
binop = BINOP_DIV;
case DW_OP_minus:
binop = BINOP_SUB;
break;
case DW_OP_mod:
binop = BINOP_MOD;
break;
case DW_OP_mul:
binop = BINOP_MUL;
break;
case DW_OP_or:
binop = BINOP_BITWISE_IOR;
break;
case DW_OP_plus:
binop = BINOP_ADD;
break;
case DW_OP_shl:
binop = BINOP_LSH;
break;
case DW_OP_shr:
binop = BINOP_RSH;
case DW_OP_shra:
binop = BINOP_RSH;
val1 = value_from_longest (signed_address_type (), first);
break;
case DW_OP_xor:
binop = BINOP_BITWISE_XOR;
break;
case DW_OP_le:
binop = BINOP_LEQ;
break;
case DW_OP_ge:
binop = BINOP_GEQ;
break;
case DW_OP_eq:
binop = BINOP_EQUAL;
break;
case DW_OP_lt:
binop = BINOP_LESS;
break;
case DW_OP_gt:
binop = BINOP_GTR;
break;
case DW_OP_ne:
binop = BINOP_NOTEQUAL;
break;
default:
internal_error (__FILE__, __LINE__,
"Can't be reached.");
}
result = value_as_long (value_binop (val1, val2, binop));
}
break;
case DW_OP_GNU_push_tls_address:
result = dwarf_expr_fetch (ctx, 0);
dwarf_expr_pop (ctx);
result = (ctx->get_tls_address) (ctx->baton, result);
break;
case DW_OP_skip:
offset = extract_signed_integer (op_ptr, 2);
op_ptr += 2;
op_ptr += offset;
goto no_push;
case DW_OP_bra:
offset = extract_signed_integer (op_ptr, 2);
op_ptr += 2;
if (dwarf_expr_fetch (ctx, 0) != 0)
op_ptr += offset;
dwarf_expr_pop (ctx);
goto no_push;
case DW_OP_nop:
goto no_push;
default:
error ("Unhandled dwarf expression opcode");
}
/* Most things push a result value. */
dwarf_expr_push (ctx, result);
no_push:;
}
}
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