diff options
Diffstat (limited to 'gdb/dwarf2loc.c')
| -rw-r--r-- | gdb/dwarf2loc.c | 351 |
1 files changed, 351 insertions, 0 deletions
diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c new file mode 100644 index 00000000000..55de8dae74e --- /dev/null +++ b/gdb/dwarf2loc.c @@ -0,0 +1,351 @@ +/* DWARF 2 location expression support for GDB. + Copyright 2003 Free Software Foundation, Inc. + Contributed by Daniel Jacobowitz, MontaVista Software, Inc. + + 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 "ui-out.h" +#include "value.h" +#include "frame.h" +#include "gdbcore.h" +#include "target.h" +#include "inferior.h" +#include "ax.h" +#include "ax-gdb.h" + +#include "elf/dwarf2.h" +#include "dwarf2expr.h" +#include "dwarf2loc.h" + +#include "gdb_string.h" + +#ifndef DWARF2_REG_TO_REGNUM +#define DWARF2_REG_TO_REGNUM(REG) (REG) +#endif + +/* This is the baton used when performing dwarf2 expression + evaluation. */ +struct dwarf_expr_baton +{ + struct frame_info *frame; + struct objfile *objfile; +}; + +/* 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. */ +static CORE_ADDR +dwarf_expr_read_reg (void *baton, int regnum, enum lval_type *lvalp, + CORE_ADDR *addrp) +{ + 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)); + + 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) +{ + read_memory (addr, buf, len); +} + +/* Using the frame specified in BATON, find the location expression + 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) +{ + 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; +} + +/* Using the objfile specified in BATON, find the address for the + current thread's thread-local storage with offset OFFSET. */ +static CORE_ADDR +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; +} + +/* Evaluate a location description, starting at DATA and with length + SIZE, to find the current location of variable VAR in the context + of FRAME. */ +static struct value * +dwarf2_evaluate_loc_desc (struct symbol *var, struct frame_info *frame, + unsigned char *data, unsigned short size, + struct objfile *objfile) +{ + CORE_ADDR result; + struct value *retval; + struct dwarf_expr_baton baton; + struct dwarf_expr_context *ctx; + + baton.frame = frame; + baton.objfile = objfile; + + ctx = new_dwarf_expr_context (); + ctx->baton = &baton; + ctx->read_reg = dwarf_expr_read_reg; + ctx->read_mem = dwarf_expr_read_mem; + ctx->get_frame_base = dwarf_expr_frame_base; + 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) + { + 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; + } + else + { + result = dwarf_expr_fetch (ctx, 0); + VALUE_LVAL (retval) = lval_memory; + VALUE_LAZY (retval) = 1; + VALUE_ADDRESS (retval) = result; + } + + free_dwarf_expr_context (ctx); + + return retval; +} + + + + + +/* Helper functions and baton for dwarf2_loc_desc_needs_frame. */ + +struct needs_frame_baton +{ + int needs_frame; +}; + +/* 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) +{ + struct needs_frame_baton *nf_baton = baton; + nf_baton->needs_frame = 1; + return 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) +{ + 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) +{ + static char lit0 = DW_OP_lit0; + struct needs_frame_baton *nf_baton = baton; + + *start = &lit0; + *length = 1; + + nf_baton->needs_frame = 1; +} + +/* Thread-local accesses do require a frame. */ +static CORE_ADDR +needs_frame_tls_address (void *baton, CORE_ADDR offset) +{ + struct needs_frame_baton *nf_baton = baton; + nf_baton->needs_frame = 1; + return 1; +} + +/* Return non-zero iff the location expression at DATA (length SIZE) + requires a frame to evaluate. */ + +static int +dwarf2_loc_desc_needs_frame (unsigned char *data, unsigned short size) +{ + struct needs_frame_baton baton; + struct dwarf_expr_context *ctx; + + baton.needs_frame = 0; + + ctx = new_dwarf_expr_context (); + ctx->baton = &baton; + ctx->read_reg = needs_frame_read_reg; + ctx->read_mem = needs_frame_read_mem; + ctx->get_frame_base = needs_frame_frame_base; + ctx->get_tls_address = needs_frame_tls_address; + + dwarf_expr_eval (ctx, data, size); + + free_dwarf_expr_context (ctx); + + return baton.needs_frame; +} + + + + +/* Return the value of SYMBOL in FRAME using the DWARF-2 expression + evaluator to calculate the location. */ +static struct value * +locexpr_read_variable (struct symbol *symbol, struct frame_info *frame) +{ + struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); + struct value *val; + val = dwarf2_evaluate_loc_desc (symbol, frame, dlbaton->data, dlbaton->size, + dlbaton->objfile); + + return val; +} + +/* Return non-zero iff we need a frame to evaluate SYMBOL. */ +static int +locexpr_read_needs_frame (struct symbol *symbol) +{ + struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); + return dwarf2_loc_desc_needs_frame (dlbaton->data, dlbaton->size); +} + +/* Print a natural-language description of SYMBOL to STREAM. */ +static int +locexpr_describe_location (struct symbol *symbol, struct ui_file *stream) +{ + /* FIXME: be more extensive. */ + struct dwarf2_locexpr_baton *dlbaton = SYMBOL_LOCATION_BATON (symbol); + + if (dlbaton->size == 1 + && dlbaton->data[0] >= DW_OP_reg0 + && dlbaton->data[0] <= DW_OP_reg31) + { + int regno = DWARF2_REG_TO_REGNUM (dlbaton->data[0] - DW_OP_reg0); + fprintf_filtered (stream, + "a variable in register %s", REGISTER_NAME (regno)); + 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. */ + +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); + + if (dlbaton->size == 0) + error ("Symbol \"%s\" has been optimized out.", + SYMBOL_PRINT_NAME (symbol)); + + if (dlbaton->size == 1 + && dlbaton->data[0] >= DW_OP_reg0 + && dlbaton->data[0] <= DW_OP_reg31) + { + value->kind = axs_lvalue_register; + value->u.reg = dlbaton->data[0] - DW_OP_reg0; + } + else if (dlbaton->data[0] == DW_OP_regx) + { + ULONGEST reg; + read_uleb128 (dlbaton->data + 1, dlbaton->data + dlbaton->size, + ®); + value->kind = axs_lvalue_register; + value->u.reg = reg; + } + else if (dlbaton->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; + unsigned char *buf_end; + + buf_end = read_sleb128 (dlbaton->data + 1, dlbaton->data + dlbaton->size, + &frame_offset); + if (buf_end != dlbaton->data + dlbaton->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); + + ax_const_l (ax, frame_offset); + ax_simple (ax, aop_add); + value->kind = axs_lvalue_memory; + } + else + error ("Unsupported DWARF opcode in the location of \"%s\".", + SYMBOL_PRINT_NAME (symbol)); +} + +/* The set of location functions used with the DWARF-2 expression + evaluator. */ +struct location_funcs dwarf2_locexpr_funcs = { + locexpr_read_variable, + locexpr_read_needs_frame, + locexpr_describe_location, + locexpr_tracepoint_var_ref +}; |