142 lines
5.3 KiB
C
142 lines
5.3 KiB
C
/* DWARF 2 Expression Evaluator.
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Copyright (C) 2001, 2002, 2003, 2005, 2007, 2008
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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 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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CORE_ADDR *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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/* 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, gdb_byte **start, size_t *length);
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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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#if 0
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/* Not yet implemented. */
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/* Return the location expression for the dwarf expression
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subroutine in the die at OFFSET in the current compilation unit.
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The result must be live until the current expression evaluation
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is complete. */
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unsigned char *(*get_subr) (void *baton, off_t offset, size_t *length);
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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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/* Non-zero if the result is in a register. The register number
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will be on the expression stack. */
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int in_reg;
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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 in_reg flag, and the size given as the operand to
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DW_OP_piece. We then pop the top value from the stack, clear the
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in_reg flag, 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, with in_reg clear, so that callers need not
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distinguish between the no-DW_OP_piece and one-DW_OP_piece cases.
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But expressions with no DW_OP_piece operations have no value to
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place in a piece's 'size' field; the size comes from the
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surrounding data. So the two cases need to be handled
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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. */
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struct dwarf_expr_piece
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{
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/* If IN_REG is zero, then the piece is in memory, and VALUE is its address.
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If IN_REG is non-zero, then the piece is in a register, and VALUE
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is the register number. */
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int in_reg;
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/* This piece's address or register number. */
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CORE_ADDR value;
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/* The length of the piece, in bytes. */
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ULONGEST size;
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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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void dwarf_expr_push (struct dwarf_expr_context *ctx, CORE_ADDR value);
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void dwarf_expr_pop (struct dwarf_expr_context *ctx);
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void dwarf_expr_eval (struct dwarf_expr_context *ctx, unsigned char *addr,
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size_t len);
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CORE_ADDR dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n);
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gdb_byte *read_uleb128 (gdb_byte *buf, gdb_byte *buf_end, ULONGEST * r);
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gdb_byte *read_sleb128 (gdb_byte *buf, gdb_byte *buf_end, LONGEST * r);
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CORE_ADDR dwarf2_read_address (gdb_byte *buf, gdb_byte *buf_end,
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int *bytes_read);
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#endif /* dwarf2expr.h */
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