251 lines
8.4 KiB
C
251 lines
8.4 KiB
C
/* DWARF 2 Expression Evaluator.
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Copyright (C) 2001, 2002, 2003, 2005, 2007, 2008, 2009, 2010, 2011
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Free Software Foundation, Inc.
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Contributed by Daniel Berlin <dan@dberlin.org>.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#if !defined (DWARF2EXPR_H)
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#define DWARF2EXPR_H
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/* The location of a value. */
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enum dwarf_value_location
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{
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/* The piece is in memory.
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The value on the dwarf stack is its address. */
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DWARF_VALUE_MEMORY,
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/* The piece is in a register.
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The value on the dwarf stack is the register number. */
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DWARF_VALUE_REGISTER,
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/* The piece is on the dwarf stack. */
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DWARF_VALUE_STACK,
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/* The piece is a literal. */
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DWARF_VALUE_LITERAL,
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/* The piece was optimized out. */
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DWARF_VALUE_OPTIMIZED_OUT,
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/* The piece is an implicit pointer. */
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DWARF_VALUE_IMPLICIT_POINTER
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};
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/* The dwarf expression stack. */
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struct dwarf_stack_value
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{
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struct value *value;
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/* Non-zero if the piece is in memory and is known to be
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on the program's stack. It is always ok to set this to zero.
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This is used, for example, to optimize memory access from the target.
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It can vastly speed up backtraces on long latency connections when
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"set stack-cache on". */
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int in_stack_memory;
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};
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/* The expression evaluator works with a dwarf_expr_context, describing
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its current state and its callbacks. */
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struct dwarf_expr_context
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{
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/* The stack of values, allocated with xmalloc. */
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struct dwarf_stack_value *stack;
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/* The number of values currently pushed on the stack, and the
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number of elements allocated to the stack. */
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int stack_len, stack_allocated;
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/* Target architecture to use for address operations. */
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struct gdbarch *gdbarch;
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/* Target address size in bytes. */
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int addr_size;
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/* Offset used to relocate DW_OP_addr argument. */
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CORE_ADDR offset;
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/* The evaluator is value-based, and frees values up to this point
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when the expression context is destroyed. */
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struct value *mark;
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/* An opaque argument provided by the caller, which will be passed
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to all of the callback functions. */
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void *baton;
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/* Return the value of register number REGNUM. */
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CORE_ADDR (*read_reg) (void *baton, int regnum);
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/* Read LENGTH bytes at ADDR into BUF. */
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void (*read_mem) (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t length);
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/* Return the location expression for the frame base attribute, in
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START and LENGTH. The result must be live until the current
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expression evaluation is complete. */
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void (*get_frame_base) (void *baton, const gdb_byte **start, size_t *length);
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/* Return the CFA for the frame. */
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CORE_ADDR (*get_frame_cfa) (void *baton);
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/* Return the PC for the frame. */
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CORE_ADDR (*get_frame_pc) (void *baton);
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/* Return the thread-local storage address for
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DW_OP_GNU_push_tls_address. */
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CORE_ADDR (*get_tls_address) (void *baton, CORE_ADDR offset);
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/* Execute DW_AT_location expression for the DWARF expression subroutine in
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the DIE at DIE_OFFSET in the CU from CTX. Do not touch STACK while it
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being passed to and returned from the called DWARF subroutine. */
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void (*dwarf_call) (struct dwarf_expr_context *ctx, size_t die_offset);
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/* Return the base type given by the indicated DIE. This can throw
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an exception if the DIE is invalid or does not represent a base
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type. If can also be NULL in the special case where the
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callbacks are not performing evaluation, and thus it is
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meaningful to substitute a stub type of the correct size. */
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struct type *(*get_base_type) (struct dwarf_expr_context *ctx, size_t die);
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#if 0
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/* Not yet implemented. */
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/* Return the `object address' for DW_OP_push_object_address. */
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CORE_ADDR (*get_object_address) (void *baton);
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#endif
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/* The current depth of dwarf expression recursion, via DW_OP_call*,
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DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum
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depth we'll tolerate before raising an error. */
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int recursion_depth, max_recursion_depth;
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/* Location of the value. */
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enum dwarf_value_location location;
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/* For DWARF_VALUE_LITERAL, the current literal value's length and
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data. For DWARF_VALUE_IMPLICIT_POINTER, LEN is the offset of the
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target DIE. */
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ULONGEST len;
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const gdb_byte *data;
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/* Initialization status of variable: Non-zero if variable has been
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initialized; zero otherwise. */
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int initialized;
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/* An array of pieces. PIECES points to its first element;
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NUM_PIECES is its length.
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Each time DW_OP_piece is executed, we add a new element to the
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end of this array, recording the current top of the stack, the
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current location, and the size given as the operand to
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DW_OP_piece. We then pop the top value from the stack, reset the
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location, and resume evaluation.
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The Dwarf spec doesn't say whether DW_OP_piece pops the top value
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from the stack. We do, ensuring that clients of this interface
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expecting to see a value left on the top of the stack (say, code
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evaluating frame base expressions or CFA's specified with
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DW_CFA_def_cfa_expression) will get an error if the expression
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actually marks all the values it computes as pieces.
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If an expression never uses DW_OP_piece, num_pieces will be zero.
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(It would be nice to present these cases as expressions yielding
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a single piece, so that callers need not distinguish between the
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no-DW_OP_piece and one-DW_OP_piece cases. But expressions with
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no DW_OP_piece operations have no value to place in a piece's
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'size' field; the size comes from the surrounding data. So the
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two cases need to be handled separately.) */
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int num_pieces;
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struct dwarf_expr_piece *pieces;
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};
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/* A piece of an object, as recorded by DW_OP_piece or DW_OP_bit_piece. */
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struct dwarf_expr_piece
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{
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enum dwarf_value_location location;
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union
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{
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struct
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{
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/* This piece's address, for DWARF_VALUE_MEMORY pieces. */
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CORE_ADDR addr;
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/* Non-zero if the piece is known to be in memory and on
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the program's stack. */
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int in_stack_memory;
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} mem;
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/* The piece's register number, for DWARF_VALUE_REGISTER pieces. */
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int regno;
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/* The piece's literal value, for DWARF_VALUE_STACK pieces. */
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struct value *value;
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struct
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{
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/* A pointer to the data making up this piece,
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for DWARF_VALUE_LITERAL pieces. */
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const gdb_byte *data;
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/* The length of the available data. */
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ULONGEST length;
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} literal;
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/* Used for DWARF_VALUE_IMPLICIT_POINTER. */
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struct
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{
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/* The referent DIE from DW_OP_GNU_implicit_pointer. */
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ULONGEST die;
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/* The byte offset into the resulting data. */
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LONGEST offset;
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} ptr;
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} v;
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/* The length of the piece, in bits. */
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ULONGEST size;
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/* The piece offset, in bits. */
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ULONGEST offset;
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};
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struct dwarf_expr_context *new_dwarf_expr_context (void);
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void free_dwarf_expr_context (struct dwarf_expr_context *ctx);
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struct cleanup *
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make_cleanup_free_dwarf_expr_context (struct dwarf_expr_context *ctx);
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void dwarf_expr_push_address (struct dwarf_expr_context *ctx,
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CORE_ADDR value,
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int in_stack_memory);
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void dwarf_expr_eval (struct dwarf_expr_context *ctx, const gdb_byte *addr,
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size_t len);
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struct value *dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n);
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CORE_ADDR dwarf_expr_fetch_address (struct dwarf_expr_context *ctx, int n);
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int dwarf_expr_fetch_in_stack_memory (struct dwarf_expr_context *ctx, int n);
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const gdb_byte *read_uleb128 (const gdb_byte *buf, const gdb_byte *buf_end,
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ULONGEST * r);
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const gdb_byte *read_sleb128 (const gdb_byte *buf, const gdb_byte *buf_end,
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LONGEST * r);
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const char *dwarf_stack_op_name (unsigned int);
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void dwarf_expr_require_composition (const gdb_byte *, const gdb_byte *,
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const char *);
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#endif /* dwarf2expr.h */
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