gdb

* dwarf2loc.c (struct piece_closure) <arch>: New field.
	(dwarf2_evaluate_loc_desc): Update.
	(dwarf2_loc_desc_needs_frame): Likewise.
	(allocate_piece_closure): Initialize new field.
	(read_pieced_value): Update.
	(write_pieced_value): Update.
	(copy_pieced_value_closure): Update.
	* dwarf2expr.h (enum dwarf_value_location): New.
	(struct dwarf_expr_context) <in_reg>: Remove.
	<location, len, data>: New fields.
	(struct dwarf_expr_piece) <in_reg, value>: Remove.
	<location, v>: New fields.
	* dwarf2expr.c (add_piece): Remove in_reg, value arguments.
	Update.
	(require_composition): New function.
	(execute_stack_op): Update.
	<DW_OP_implicit_value, DW_OP_stack_value>: New cases.
	<DW_OP_reg0>: Set location, not in_reg.
	<DW_OP_regx>: Likewise.  Use require_composition.
	<DW_OP_fbreg>: Update.
	<DW_OP_piece>: Likewise.
	* dwarf2-frame.c (execute_stack_op): Update.
gdb/testsuite
	* gdb.dwarf2/valop.S: New file.
	* gdb.dwarf2/valop.exp: New file.

gdb/dwarf2expr.h

@@ -23,6 +23,19 @@
 #if !defined (DWARF2EXPR_H)
 #define DWARF2EXPR_H
 
+/* The location of a value.  */
+enum dwarf_value_location
+{
+  /* The piece is in memory.  */
+  DWARF_VALUE_MEMORY,
+  /* The piece is in a register.  */
+  DWARF_VALUE_REGISTER,
+  /* The piece is on the stack.  */
+  DWARF_VALUE_STACK,
+  /* The piece is a literal.  */
+  DWARF_VALUE_LITERAL
+};
+
 /* The expression evaluator works with a dwarf_expr_context, describing
    its current state and its callbacks.  */
 struct dwarf_expr_context
@@ -80,9 +93,13 @@ struct dwarf_expr_context
      depth we'll tolerate before raising an error.  */
   int recursion_depth, max_recursion_depth;
 
-  /* Non-zero if the result is in a register.  The register number
-     will be on the expression stack.  */
-  int in_reg;
+  /* Location of the value.  */
+  enum dwarf_value_location location;
+
+  /* For VALUE_LITERAL, a the current literal value's length and
+     data.  */
+  ULONGEST len;
+  gdb_byte *data;
 
   /* Initialization status of variable: Non-zero if variable has been
      initialized; zero otherwise.  */
@@ -93,9 +110,9 @@ struct dwarf_expr_context
 
      Each time DW_OP_piece is executed, we add a new element to the
      end of this array, recording the current top of the stack, the
-     current in_reg flag, and the size given as the operand to
-     DW_OP_piece.  We then pop the top value from the stack, clear the
-     in_reg flag, and resume evaluation.
+     current location, and the size given as the operand to
+     DW_OP_piece.  We then pop the top value from the stack, rest the
+     location, and resume evaluation.
 
      The Dwarf spec doesn't say whether DW_OP_piece pops the top value
      from the stack.  We do, ensuring that clients of this interface
@@ -106,12 +123,11 @@ struct dwarf_expr_context
 
      If an expression never uses DW_OP_piece, num_pieces will be zero.
      (It would be nice to present these cases as expressions yielding
-     a single piece, with in_reg clear, so that callers need not
-     distinguish between the no-DW_OP_piece and one-DW_OP_piece cases.
-     But expressions with no DW_OP_piece operations have no value to
-     place in a piece's 'size' field; the size comes from the
-     surrounding data.  So the two cases need to be handled
-     separately.)  */
+     a single piece, so that callers need not distinguish between the
+     no-DW_OP_piece and one-DW_OP_piece cases.  But expressions with
+     no DW_OP_piece operations have no value to place in a piece's
+     'size' field; the size comes from the surrounding data.  So the
+     two cases need to be handled separately.)  */
   int num_pieces;
   struct dwarf_expr_piece *pieces;
 };
@@ -120,13 +136,22 @@ struct dwarf_expr_context
 /* A piece of an object, as recorded by DW_OP_piece.  */
 struct dwarf_expr_piece
 {
-  /* If IN_REG is zero, then the piece is in memory, and VALUE is its address.
-     If IN_REG is non-zero, then the piece is in a register, and VALUE
-     is the register number.  */
-  int in_reg;
+  enum dwarf_value_location location;
 
-  /* This piece's address or register number.  */
-  CORE_ADDR value;
+  union
+  {
+    /* This piece's address or register number.  */
+    CORE_ADDR value;
+
+    struct
+    {
+      /* A pointer to the data making up this piece, for literal
+	 pieces.  */
+      gdb_byte *data;
+      /* The length of the available data.  */
+      ULONGEST length;
+    } literal;
+  } v;
 
   /* The length of the piece, in bytes.  */
   ULONGEST size;