Re: Regression: Re: RFC: implement typed DWARF stack

[Tom Tromey <tromey@redhat.com>]

Jan> This is 15MB .sum diff of regressions, nothing works now.

Yeah, I apologize for that.  I didn't run the final version through the
tester, neglecting that I had made a major change.

Here is the fix I am checking in.  The bug was that we were calling
value_free_to_mark but then using values from the value list.  The fix
is to be more careful about ordering cleanups.

Built and regtested on the buildbot.

Jan> +# This test can only be run on x86 targets.
Jan> +if { ![istarget i?86-*] } {
Jan> +    return 0
Jan> +}

Jan> It will not run on x86_64 box with -m32 while it could, I would
Jan> prefer there also x86_64 target with is_ilp32_target conditional.

I will make this change separately.

Tom

2011-05-13  Tom Tromey  <tromey@redhat.com>

	* utils.c (do_value_free): New function.
	(make_cleanup_value_free): Likewise.
	* dwarf2loc.c (dwarf2_evaluate_loc_desc_full): Handle value
	freeing correctly.
	(dwarf2_loc_desc_needs_frame): Call
	make_cleanup_value_free_to_mark.
	* dwarf2expr.h (struct dwarf_expr_context) <mark>: Remove field.
	* dwarf2expr.c (free_dwarf_expr_context): Don't call
	value_free_to_mark.
	(new_dwarf_expr_context): Don't call value_mark.
	* dwarf2-frame.c (execute_stack_op): Call
	make_cleanup_value_free_to_mark.
	* defs.h (make_cleanup_value_free): Declare.

diff --git a/gdb/defs.h b/gdb/defs.h
index 771d3ad..38a2fcf 100644
--- a/gdb/defs.h
+++ b/gdb/defs.h
@@ -362,6 +362,7 @@ extern struct cleanup *
   make_cleanup_restore_ui_file (struct ui_file **variable);
 
 extern struct cleanup *make_cleanup_value_free_to_mark (struct value *);
+extern struct cleanup *make_cleanup_value_free (struct value *);
 
 extern struct cleanup *make_final_cleanup (make_cleanup_ftype *, void *);
 
diff --git a/gdb/dwarf2-frame.c b/gdb/dwarf2-frame.c
index 4e4e6d9..fe48713 100644
--- a/gdb/dwarf2-frame.c
+++ b/gdb/dwarf2-frame.c
@@ -402,6 +402,7 @@ execute_stack_op (const gdb_byte *exp, ULONGEST len, int addr_size,
 
   ctx = new_dwarf_expr_context ();
   old_chain = make_cleanup_free_dwarf_expr_context (ctx);
+  make_cleanup_value_free_to_mark (value_mark ());
 
   ctx->gdbarch = get_frame_arch (this_frame);
   ctx->addr_size = addr_size;
diff --git a/gdb/dwarf2expr.c b/gdb/dwarf2expr.c
index 0c0760b..b42f289 100644
--- a/gdb/dwarf2expr.c
+++ b/gdb/dwarf2expr.c
@@ -104,7 +104,6 @@ new_dwarf_expr_context (void)
   retval->num_pieces = 0;
   retval->pieces = 0;
   retval->max_recursion_depth = 0x100;
-  retval->mark = value_mark ();
   return retval;
 }
 
@@ -113,7 +112,6 @@ new_dwarf_expr_context (void)
 void
 free_dwarf_expr_context (struct dwarf_expr_context *ctx)
 {
-  value_free_to_mark (ctx->mark);
   xfree (ctx->stack);
   xfree (ctx->pieces);
   xfree (ctx);
diff --git a/gdb/dwarf2expr.h b/gdb/dwarf2expr.h
index 281c65b..676b54b 100644
--- a/gdb/dwarf2expr.h
+++ b/gdb/dwarf2expr.h
@@ -81,10 +81,6 @@ struct dwarf_expr_context
   /* Offset used to relocate DW_OP_addr argument.  */
   CORE_ADDR offset;
 
-  /* The evaluator is value-based, and frees values up to this point
-     when the expression context is destroyed.  */
-  struct value *mark;
-
   /* An opaque argument provided by the caller, which will be passed
      to all of the callback functions.  */
   void *baton;
diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c
index 04f16e9..64cc5e5 100644
--- a/gdb/dwarf2loc.c
+++ b/gdb/dwarf2loc.c
@@ -1086,7 +1086,7 @@ dwarf2_evaluate_loc_desc_full (struct type *type, struct frame_info *frame,
   struct value *retval;
   struct dwarf_expr_baton baton;
   struct dwarf_expr_context *ctx;
-  struct cleanup *old_chain;
+  struct cleanup *old_chain, *value_chain;
   struct objfile *objfile = dwarf2_per_cu_objfile (per_cu);
   volatile struct gdb_exception ex;
 
@@ -1106,6 +1106,7 @@ dwarf2_evaluate_loc_desc_full (struct type *type, struct frame_info *frame,
 
   ctx = new_dwarf_expr_context ();
   old_chain = make_cleanup_free_dwarf_expr_context (ctx);
+  value_chain = make_cleanup_value_free_to_mark (value_mark ());
 
   ctx->gdbarch = get_objfile_arch (objfile);
   ctx->addr_size = dwarf2_per_cu_addr_size (per_cu);
@@ -1128,6 +1129,7 @@ dwarf2_evaluate_loc_desc_full (struct type *type, struct frame_info *frame,
     {
       if (ex.error == NOT_AVAILABLE_ERROR)
 	{
+	  do_cleanups (old_chain);
 	  retval = allocate_value (type);
 	  mark_value_bytes_unavailable (retval, 0, TYPE_LENGTH (type));
 	  return retval;
@@ -1150,6 +1152,9 @@ dwarf2_evaluate_loc_desc_full (struct type *type, struct frame_info *frame,
 
       c = allocate_piece_closure (per_cu, ctx->num_pieces, ctx->pieces,
 				  ctx->addr_size);
+      /* We must clean up the value chain after creating the piece
+	 closure but before allocating the result.  */
+      do_cleanups (value_chain);
       retval = allocate_computed_value (type, &pieced_value_funcs, c);
       VALUE_FRAME_ID (retval) = frame_id;
       set_value_offset (retval, byte_offset);
@@ -1166,6 +1171,7 @@ dwarf2_evaluate_loc_desc_full (struct type *type, struct frame_info *frame,
 
 	    if (byte_offset != 0)
 	      error (_("cannot use offset on synthetic pointer to register"));
+	    do_cleanups (value_chain);
 	    if (gdb_regnum != -1)
 	      retval = value_from_register (type, gdb_regnum, frame);
 	    else
@@ -1179,6 +1185,7 @@ dwarf2_evaluate_loc_desc_full (struct type *type, struct frame_info *frame,
 	    CORE_ADDR address = dwarf_expr_fetch_address (ctx, 0);
 	    int in_stack_memory = dwarf_expr_fetch_in_stack_memory (ctx, 0);
 
+	    do_cleanups (value_chain);
 	    retval = allocate_value_lazy (type);
 	    VALUE_LVAL (retval) = lval_memory;
 	    if (in_stack_memory)
@@ -1201,6 +1208,13 @@ dwarf2_evaluate_loc_desc_full (struct type *type, struct frame_info *frame,
 	    val_bytes += byte_offset;
 	    n -= byte_offset;
 
+	    /* Preserve VALUE because we are going to free values back
+	       to the mark, but we still need the value contents
+	       below.  */
+	    value_incref (value);
+	    do_cleanups (value_chain);
+	    make_cleanup_value_free (value);
+
 	    retval = allocate_value (type);
 	    contents = value_contents_raw (retval);
 	    if (n > TYPE_LENGTH (type))
@@ -1218,6 +1232,7 @@ dwarf2_evaluate_loc_desc_full (struct type *type, struct frame_info *frame,
 	    if (byte_offset + TYPE_LENGTH (type) > n)
 	      invalid_synthetic_pointer ();
 
+	    do_cleanups (value_chain);
 	    retval = allocate_value (type);
 	    contents = value_contents_raw (retval);
 
@@ -1231,6 +1246,7 @@ dwarf2_evaluate_loc_desc_full (struct type *type, struct frame_info *frame,
 	  break;
 
 	case DWARF_VALUE_OPTIMIZED_OUT:
+	  do_cleanups (value_chain);
 	  retval = allocate_value (type);
 	  VALUE_LVAL (retval) = not_lval;
 	  set_value_optimized_out (retval, 1);
@@ -1353,6 +1369,7 @@ dwarf2_loc_desc_needs_frame (const gdb_byte *data, unsigned short size,
 
   ctx = new_dwarf_expr_context ();
   old_chain = make_cleanup_free_dwarf_expr_context (ctx);
+  make_cleanup_value_free_to_mark (value_mark ());
 
   ctx->gdbarch = get_objfile_arch (objfile);
   ctx->addr_size = dwarf2_per_cu_addr_size (per_cu);
diff --git a/gdb/utils.c b/gdb/utils.c
index 3e4a54d..6fd220a 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -448,6 +448,22 @@ make_cleanup_value_free_to_mark (struct value *mark)
   return make_my_cleanup (&cleanup_chain, do_value_free_to_mark, mark);
 }
 
+/* Helper for make_cleanup_value_free.  */
+
+static void
+do_value_free (void *value)
+{
+  value_free (value);
+}
+
+/* Free VALUE.  */
+
+struct cleanup *
+make_cleanup_value_free (struct value *value)
+{
+  return make_my_cleanup (&cleanup_chain, do_value_free, value);
+}
+
 struct cleanup *
 make_my_cleanup2 (struct cleanup **pmy_chain, make_cleanup_ftype *function,
 		  void *arg,  void (*free_arg) (void *))