Fix dwarf_expr_context method regressions

This fixes some regressions found in the patch to convert
dwarf_expr_context to use methods.  Specifically:

* get_base_type could erroneously throw; this was rewritten to move
  the size checks into the only spot needing them.
* Previously the "symbol needs frame" implementation reused th
  "cfa" function for the get_frame_pc slot; this reimplements
  it under the correct name.
* Not enough members were saved and restored in one implementation
  of push_dwarf_reg_entry_value; this patch fixes this oversight
  and also takes the opportunity to remove an extraneous structure
  definition.

2016-11-02  Tom Tromey  <tom@tromey.com>

	* dwarf2loc.c (dwarf_evaluate_loc_desc::get_base_type): Rename
	from impl_get_base_type.  Rewrite.
	(struct dwarf_expr_baton): Remove.
	(dwarf_evaluate_loc_desc::push_dwarf_reg_entry_value): Save and
	restore more fields.
	(symbol_needs_eval_context::get_frame_pc): New method.
	* dwarf2expr.h (dwarf_expr_context::get_base_type): Now public,
	virtual.
	(dwarf_expr_context::impl_get_base_type): Remove.
	* dwarf2expr.c (dwarf_expr_context::get_base_type): Remove.

4 files changed, 38 insertions, 31 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index b4dce194261..8ce613213cf 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,16 @@
+2016-11-02  Tom Tromey  <tom@tromey.com>
+
+	* dwarf2loc.c (dwarf_evaluate_loc_desc::get_base_type): Rename
+	from impl_get_base_type.  Rewrite.
+	(struct dwarf_expr_baton): Remove.
+	(dwarf_evaluate_loc_desc::push_dwarf_reg_entry_value): Save and
+	restore more fields.
+	(symbol_needs_eval_context::get_frame_pc): New method.
+	* dwarf2expr.h (dwarf_expr_context::get_base_type): Now public,
+	virtual.
+	(dwarf_expr_context::impl_get_base_type): Remove.
+	* dwarf2expr.c (dwarf_expr_context::get_base_type): Remove.
+
 2016-10-31  Maciej W. Rozycki  <macro@imgtec.com>
 
 	* configure.ac <mips-sgi-irix5*>: Remove <sys/proc.h> _KMEMUSER
diff --git a/gdb/dwarf2expr.c b/gdb/dwarf2expr.c
index a01d6d8e3a3..398ca0eac6a 100644
--- a/gdb/dwarf2expr.c
+++ b/gdb/dwarf2expr.c
@@ -406,22 +406,6 @@ base_types_equal_p (struct type *t1, struct type *t2)
   return TYPE_LENGTH (t1) == TYPE_LENGTH (t2);
 }
 
-/* A convenience function to call get_base_type and return the result.
-   DIE is the DIE whose type we need.  SIZE is non-zero if this
-   function should verify that the resulting type has the correct
-   size.  */
-
-struct type *
-dwarf_expr_context::get_base_type (cu_offset die, int size)
-{
-  struct type *result = this->impl_get_base_type (die);
-  if (result == NULL)
-    error (_("Could not find type for DW_OP_GNU_const_type"));
-  if (size != 0 && TYPE_LENGTH (result) != size)
-    error (_("DW_OP_GNU_const_type has different sizes for type and data"));
-  return result;
-}
-
 /* If <BUF..BUF_END] contains DW_FORM_block* with single DW_OP_reg* return the
    DWARF register number.  Otherwise return -1.  */
 
diff --git a/gdb/dwarf2expr.h b/gdb/dwarf2expr.h
index 3d081202dbd..883c54c3043 100644
--- a/gdb/dwarf2expr.h
+++ b/gdb/dwarf2expr.h
@@ -179,10 +179,9 @@ struct dwarf_expr_context
 
   /* Return the base type given by the indicated DIE.  This can throw
      an exception if the DIE is invalid or does not represent a base
-     type.  If can also be NULL in the special case where the
-     callbacks are not performing evaluation, and thus it is
-     meaningful to substitute a stub type of the correct size.  */
-  virtual struct type *impl_get_base_type (cu_offset die)
+     type.  SIZE is non-zero if this function should verify that the
+     resulting type has the correct size.  */
+  virtual struct type *get_base_type (cu_offset die, int size)
   {
     /* Anything will do.  */
     return builtin_type (this->gdbarch)->builtin_int;
@@ -210,7 +209,6 @@ private:
   void push (struct value *value, int in_stack_memory);
   int stack_empty_p () const;
   void add_piece (ULONGEST size, ULONGEST offset);
-  struct type *get_base_type (cu_offset die, int size);
   void execute_stack_op (const gdb_byte *op_ptr, const gdb_byte *op_end);
   void pop ();
 };
diff --git a/gdb/dwarf2loc.c b/gdb/dwarf2loc.c
index 6f253145e32..93aec1fbfcf 100644
--- a/gdb/dwarf2loc.c
+++ b/gdb/dwarf2loc.c
@@ -515,10 +515,14 @@ class dwarf_evaluate_loc_desc : public dwarf_expr_context
     per_cu_dwarf_call (this, die_offset, per_cu);
   }
 
-  /* Callback function for dwarf2_evaluate_loc_desc.  */
-  struct type *impl_get_base_type (cu_offset die_offset) OVERRIDE
+  struct type *get_base_type (cu_offset die_offset, int size) OVERRIDE
   {
-    return dwarf2_get_die_type (die_offset, per_cu);
+    struct type *result = dwarf2_get_die_type (die_offset, per_cu);
+    if (result == NULL)
+      error (_("Could not find type for DW_OP_GNU_const_type"));
+    if (size != 0 && TYPE_LENGTH (result) != size)
+      error (_("DW_OP_GNU_const_type has different sizes for type and data"));
+    return result;
   }
 
   /* Callback function for dwarf2_evaluate_loc_desc.
@@ -553,7 +557,6 @@ class dwarf_evaluate_loc_desc : public dwarf_expr_context
   {
     struct frame_info *caller_frame;
     struct dwarf2_per_cu_data *caller_per_cu;
-    struct dwarf_expr_baton baton_local;
     struct call_site_parameter *parameter;
     const gdb_byte *data_src;
     size_t size;
@@ -570,17 +573,20 @@ class dwarf_evaluate_loc_desc : public dwarf_expr_context
       throw_error (NO_ENTRY_VALUE_ERROR,
 		   _("Cannot resolve DW_AT_GNU_call_site_data_value"));
 
-    baton_local.frame = caller_frame;
-    baton_local.per_cu = caller_per_cu;
-    baton_local.obj_address = 0;
+    scoped_restore save_frame = make_scoped_restore (&this->frame,
+						     caller_frame);
+    scoped_restore save_per_cu = make_scoped_restore (&this->per_cu,
+						      caller_per_cu);
+    scoped_restore save_obj_addr = make_scoped_restore (&this->obj_address,
+							(CORE_ADDR) 0);
 
     scoped_restore save_arch = make_scoped_restore (&this->gdbarch);
     this->gdbarch
-      = get_objfile_arch (dwarf2_per_cu_objfile (baton_local.per_cu));
+      = get_objfile_arch (dwarf2_per_cu_objfile (per_cu));
     scoped_restore save_addr_size = make_scoped_restore (&this->addr_size);
-    this->addr_size = dwarf2_per_cu_addr_size (baton_local.per_cu);
+    this->addr_size = dwarf2_per_cu_addr_size (per_cu);
     scoped_restore save_offset = make_scoped_restore (&this->offset);
-    this->offset = dwarf2_per_cu_text_offset (baton_local.per_cu);
+    this->offset = dwarf2_per_cu_text_offset (per_cu);
 
     this->eval (data_src, size);
   }
@@ -2707,6 +2713,12 @@ class symbol_needs_eval_context : public dwarf_expr_context
     return 1;
   }
 
+  CORE_ADDR get_frame_pc () OVERRIDE
+  {
+    needs = SYMBOL_NEEDS_FRAME;
+    return 1;
+  }
+
   /* Thread-local accesses require registers, but not a frame.  */
   CORE_ADDR get_tls_address (CORE_ADDR offset) OVERRIDE
   {