[PATCH 04/30] Move compilation unit info to dwarf_expr_context

[Zoran Zaric via Gdb-patches <gdb-patches@sourceware.org>]

From: Zoran Zaric <zoran.zaric@amd.com>

This patch moves the compilation unit context information and support
from dwarf_expr_executor and dwarf_evaluate_loc_desc to
dwarf_expr_context evaluator. The idea is to report an error when a
given operation requires a compilation unit information to be resolved,
which is not available.

gdb/ChangeLog:

	* dwarf2/expr.c (ensure_have_per_cu): New function.
	(dwarf_expr_context::dwarf_expr_context): Add compilation unit
	context information.
	(dwarf_expr_context::get_base_type): Move from
	dwarf_evaluate_loc_desc.
	(dwarf_expr_context::get_addr_index): Remove method.
	(dwarf_expr_context::dwarf_variable_value): Remove method.
	(dwarf_expr_context::execute_stack_op): Call compilation unit
	context info check. Inline get_addr_index and
	dwarf_variable_value methods.
	* dwarf2/expr.h (struct dwarf_expr_context): Add compilation
	context info. Remove get_addr_index and dwarf_variable_value.
	* dwarf2/frame.c (dwarf_expr_executor::get_addr_index): Remove
	method.
	(dwarf_expr_executor::dwarf_variable_value): Remove method.
	* dwarf2/loc.c (sect_variable_value): Expose function.
	(dwarf_evaluate_loc_desc::get_addr_index): Remove method.
	(dwarf_evaluate_loc_desc::dwarf_variable_value): Remove method.
	(class dwarf_evaluate_loc_desc): Move compilation unit context
	information to dwarf_expr_context class.
	* dwarf2/loc.h (sect_variable_value): Expose function.
---
 gdb/dwarf2/expr.c  | 54 ++++++++++++++++++++++++++++++++++++++--------
 gdb/dwarf2/expr.h  | 26 ++++++++--------------
 gdb/dwarf2/frame.c | 10 ---------
 gdb/dwarf2/loc.c   | 35 +++---------------------------
 gdb/dwarf2/loc.h   |  8 +++++++
 5 files changed, 65 insertions(+), 68 deletions(-)

diff --git a/gdb/dwarf2/expr.c b/gdb/dwarf2/expr.c
index 6ba8b90c58..29f5f977ac 100644
--- a/gdb/dwarf2/expr.c
+++ b/gdb/dwarf2/expr.c
@@ -68,6 +68,16 @@ ensure_have_frame (struct frame_info *frame, const char *op_name)
 		 _("%s evaluation requires a frame."), op_name);
 }
 
+/* Ensure that a PER_CU is defined and throw an exception otherwise.  */
+
+static void
+ensure_have_per_cu (struct dwarf2_per_cu_data *per_cu, const char* op_name)
+{
+  if (per_cu == nullptr)
+    throw_error (GENERIC_ERROR,
+		 _("%s evaluation requires a compilation unit."), op_name);
+}
+
 /* See expr.h.  */
 
 CORE_ADDR
@@ -123,7 +133,8 @@ dwarf_expr_context::dwarf_expr_context (dwarf2_per_objfile *per_objfile)
   data (NULL),
   initialized (0),
   per_objfile (per_objfile),
-  frame (nullptr)
+  frame (nullptr),
+  per_cu (nullptr)
 {
 }
 
@@ -207,6 +218,25 @@ dwarf_expr_context::get_frame_base (const gdb_byte **start,
 				   start, length);
 }
 
+/* See expr.h.  */
+
+struct type *
+dwarf_expr_context::get_base_type (cu_offset die_cu_off, int size)
+{
+  if (per_cu == nullptr)
+    return builtin_type (this->gdbarch)->builtin_int;
+
+  struct type *result = dwarf2_get_die_type (die_cu_off, per_cu, per_objfile);
+
+  if (result == NULL)
+    error (_("Could not find type for DW_OP_const_type"));
+
+  if (size != 0 && TYPE_LENGTH (result) != size)
+    error (_("DW_OP_const_type has different sizes for type and data"));
+
+  return result;
+}
+
 /* Require that TYPE be an integral type; throw an exception if not.  */
 
 static void
@@ -703,14 +733,20 @@ dwarf_expr_context::execute_stack_op (const gdb_byte *op_ptr,
 
 	case DW_OP_addrx:
 	case DW_OP_GNU_addr_index:
+	  ensure_have_per_cu (this->per_cu, "DW_OP_addrx");
+
 	  op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
-	  result = this->get_addr_index (uoffset);
+	  result = dwarf2_read_addr_index (this->per_cu, this->per_objfile,
+					   uoffset);
 	  result += this->per_objfile->objfile->text_section_offset ();
 	  result_val = value_from_ulongest (address_type, result);
 	  break;
 	case DW_OP_GNU_const_index:
+	  ensure_have_per_cu (per_cu, "DW_OP_GNU_const_index");
+
 	  op_ptr = safe_read_uleb128 (op_ptr, op_end, &uoffset);
-	  result = this->get_addr_index (uoffset);
+	  result = dwarf2_read_addr_index (this->per_cu, this->per_objfile,
+					   uoffset);
 	  result_val = value_from_ulongest (address_type, result);
 	  break;
 
@@ -840,10 +876,7 @@ dwarf_expr_context::execute_stack_op (const gdb_byte *op_ptr,
 	case DW_OP_GNU_implicit_pointer:
 	  {
 	    int64_t len;
-
-	    if (this->ref_addr_size == -1)
-	      error (_("DWARF-2 expression error: DW_OP_implicit_pointer "
-		       "is not allowed in frame context"));
+	    ensure_have_per_cu (per_cu, "DW_OP_implicit_pointer");
 
 	    /* The referred-to DIE of sect_offset kind.  */
 	    this->len = extract_unsigned_integer (op_ptr, this->ref_addr_size,
@@ -1336,13 +1369,16 @@ dwarf_expr_context::execute_stack_op (const gdb_byte *op_ptr,
 
 	case DW_OP_GNU_variable_value:
 	  {
+	    ensure_have_per_cu (per_cu, "DW_OP_GNU_variable_value");
+
 	    sect_offset sect_off
 	      = (sect_offset) extract_unsigned_integer (op_ptr,
 							this->ref_addr_size,
 							byte_order);
 	    op_ptr += this->ref_addr_size;
-	    result_val = value_cast (address_type,
-				     this->dwarf_variable_value (sect_off));
+	    result_val = sect_variable_value (sect_off, this->per_cu,
+					      this->per_objfile);
+	    result_val = value_cast (address_type, result_val);
 	  }
 	  break;
 	
diff --git a/gdb/dwarf2/expr.h b/gdb/dwarf2/expr.h
index 5abb870f88..e17cd99c25 100644
--- a/gdb/dwarf2/expr.h
+++ b/gdb/dwarf2/expr.h
@@ -189,6 +189,9 @@ struct dwarf_expr_context
   /* Frame information used for the evaluation.  */
   struct frame_info *frame;
 
+  /* Compilation unit used for the evaluation.  */
+  struct dwarf2_per_cu_data *per_cu;
+
   /* Read LENGTH bytes at ADDR into BUF.  */
   virtual void read_mem (gdb_byte *buf, CORE_ADDR addr, size_t length) = 0;
 
@@ -208,19 +211,6 @@ struct dwarf_expr_context
      subroutine.  */
   virtual void dwarf_call (cu_offset die_cu_off) = 0;
 
-  /* Execute "variable value" operation on the DIE at SECT_OFF.  */
-  virtual struct value *dwarf_variable_value (sect_offset sect_off) = 0;
-
-  /* Return the base type given by the indicated DIE at DIE_CU_OFF.
-     This can throw an exception if the DIE is invalid or does not
-     represent a base 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_cu_off, int size)
-  {
-    /* Anything will do.  */
-    return builtin_type (this->gdbarch)->builtin_int;
-  }
-
   /* Push on DWARF stack an entry evaluated for DW_TAG_call_site's
      parameter matching KIND and KIND_U at the caller of specified BATON.
      If DEREF_SIZE is not -1 then use DW_AT_call_data_value instead of
@@ -229,10 +219,6 @@ struct dwarf_expr_context
 					   union call_site_parameter_u kind_u,
 					   int deref_size) = 0;
 
-  /* Return the address indexed by DW_OP_addrx or DW_OP_GNU_addr_index.
-     This can throw an exception if the index is out of range.  */
-  virtual CORE_ADDR get_addr_index (unsigned int index) = 0;
-
   /* Return the `object address' for DW_OP_push_object_address.  */
   virtual CORE_ADDR get_object_address () = 0;
 
@@ -255,6 +241,12 @@ struct dwarf_expr_context
      START and LENGTH.  The result must be live until the current
      expression evaluation is complete.  */
   void get_frame_base (const gdb_byte **start, size_t *length);
+
+  /* Return the base type given by the indicated DIE at DIE_CU_OFF.
+     This can throw an exception if the DIE is invalid or does not
+     represent a base type.  SIZE is non-zero if this function should
+     verify that the resulting type has the correct size.  */
+  struct type *get_base_type (cu_offset die_cu_off, int size);
 };
 
 /* Return the value of register number REG (a DWARF register number),
diff --git a/gdb/dwarf2/frame.c b/gdb/dwarf2/frame.c
index 4cc0ffe3c5..c93ec5d5a6 100644
--- a/gdb/dwarf2/frame.c
+++ b/gdb/dwarf2/frame.c
@@ -258,16 +258,6 @@ class dwarf_expr_executor : public dwarf_expr_context
     invalid ("DW_OP_call*");
   }
 
-  struct value *dwarf_variable_value (sect_offset sect_off) override
-  {
-    invalid ("DW_OP_GNU_variable_value");
-  }
-
-  CORE_ADDR get_addr_index (unsigned int index) override
-  {
-    invalid ("DW_OP_addrx or DW_OP_GNU_addr_index");
-  }
-
  private:
 
   void invalid (const char *op) ATTRIBUTE_NORETURN
diff --git a/gdb/dwarf2/loc.c b/gdb/dwarf2/loc.c
index ecf1020b3b..21e43e399c 100644
--- a/gdb/dwarf2/loc.c
+++ b/gdb/dwarf2/loc.c
@@ -620,12 +620,10 @@ per_cu_dwarf_call (struct dwarf_expr_context *ctx, cu_offset die_offset,
   ctx->eval (block.data, block.size);
 }
 
-/* Given context CTX, section offset SECT_OFF, and compilation unit
-   data PER_CU, execute the "variable value" operation on the DIE
-   found at SECT_OFF.  */
+/* See loc.h.  */
 
-static struct value *
-sect_variable_value (struct dwarf_expr_context *ctx, sect_offset sect_off,
+struct value *
+sect_variable_value (sect_offset sect_off,
 		     dwarf2_per_cu_data *per_cu,
 		     dwarf2_per_objfile *per_objfile)
 {
@@ -654,7 +652,6 @@ class dwarf_evaluate_loc_desc : public dwarf_expr_context
     : dwarf_expr_context (per_objfile)
   {}
 
-  struct dwarf2_per_cu_data *per_cu;
   CORE_ADDR obj_address;
 
   /* Helper function for dwarf2_evaluate_loc_desc.  Computes the PC for
@@ -680,32 +677,6 @@ class dwarf_evaluate_loc_desc : public dwarf_expr_context
     per_cu_dwarf_call (this, die_offset, per_cu, per_objfile);
   }
 
-  /* Helper interface of sect_variable_value for
-     dwarf2_evaluate_loc_desc.  */
-
-  struct value *dwarf_variable_value (sect_offset sect_off) override
-  {
-    return sect_variable_value (this, sect_off, per_cu, per_objfile);
-  }
-
-  struct type *get_base_type (cu_offset die_offset, int size) override
-  {
-    struct type *result = dwarf2_get_die_type (die_offset, per_cu, per_objfile);
-    if (result == NULL)
-      error (_("Could not find type for DW_OP_const_type"));
-    if (size != 0 && TYPE_LENGTH (result) != size)
-      error (_("DW_OP_const_type has different sizes for type and data"));
-    return result;
-  }
-
-  /* Callback function for dwarf2_evaluate_loc_desc.
-     Fetch the address indexed by DW_OP_addrx or DW_OP_GNU_addr_index.  */
-
-  CORE_ADDR get_addr_index (unsigned int index) override
-  {
-    return dwarf2_read_addr_index (per_cu, per_objfile, index);
-  }
-
   /* Callback function for get_object_address. Return the address of the VLA
      object.  */
 
diff --git a/gdb/dwarf2/loc.h b/gdb/dwarf2/loc.h
index 907455b72c..85700ea99d 100644
--- a/gdb/dwarf2/loc.h
+++ b/gdb/dwarf2/loc.h
@@ -53,6 +53,14 @@ extern void func_get_frame_base_dwarf_block (struct symbol *framefunc,
 					     const gdb_byte **start,
 					     size_t *length);
 
+/* Given section offset SECT_OFF, and compilation unit data
+   PER_CU, execute the "variable value" operation on the DIE
+   found at SECT_OFF.  */
+
+struct value *sect_variable_value (sect_offset sect_off,
+				   dwarf2_per_cu_data *per_cu,
+				   dwarf2_per_objfile *per_objfile);
+
 /* Evaluate a location description, starting at DATA and with length
    SIZE, to find the current location of variable of TYPE in the context
    of FRAME.  */
-- 
2.17.1