| /* 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 "regcache.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 dwarf_regnum, enum lval_type *lvalp, |
| CORE_ADDR *addrp) |
| { |
| struct dwarf_expr_baton *debaton = (struct dwarf_expr_baton *) baton; |
| CORE_ADDR result; |
| char *buf; |
| int optimized, regnum, realnum, regsize; |
| |
| regnum = DWARF2_REG_TO_REGNUM (dwarf_regnum); |
| regsize = register_size (current_gdbarch, regnum); |
| buf = (char *) alloca (regsize); |
| |
| frame_register (debaton->frame, regnum, &optimized, lvalp, addrp, &realnum, |
| buf); |
| result = extract_address (buf, regsize); |
| |
| 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 |
| }; |