1 files changed, 287 insertions, 0 deletions

diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c
new file mode 100644
index 0000000..330765d
--- /dev/null
+++ b/gdb/dwarf2loc.c
@@ -0,0 +1,287 @@
+/* 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 "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;
+}
+
+/* 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,
+  NULL
+};