[binutils-gdb] Introduce subscript_operation

[Tom Tromey]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=224d6424bab021a0a8e16f07d52f8af5e153e91f

commit 224d6424bab021a0a8e16f07d52f8af5e153e91f
Author: Tom Tromey <tom@tromey.com>
Date:   Mon Mar 8 07:27:57 2021 -0700

    Introduce subscript_operation
    
    This adds class subscript_operation, which implements BINOP_SUBSCRIPT.
    
    gdb/ChangeLog
    2021-03-08  Tom Tromey  <tom@tromey.com>
    
            * expop.h (class subscript_operation): New.
            * eval.c (eval_op_subscript): No longer static.

Diff:
---
 gdb/ChangeLog |  5 +++++
 gdb/eval.c    | 35 ++++++++++++++++++++++++++++++++++-
 gdb/expop.h   | 16 ++++++++++++++++
 3 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 0ed474f176c..b84ebfb1ec7 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2021-03-08  Tom Tromey  <tom@tromey.com>
+
+	* expop.h (class subscript_operation): New.
+	* eval.c (eval_op_subscript): No longer static.
+
 2021-03-08  Tom Tromey  <tom@tromey.com>
 
 	* expop.h (class binop_operation, class usual_ax_binop_operation):
diff --git a/gdb/eval.c b/gdb/eval.c
index 6fde03d3522..056daa05160 100644
--- a/gdb/eval.c
+++ b/gdb/eval.c
@@ -1558,7 +1558,7 @@ eval_op_binary (struct type *expect_type, struct expression *exp,
 
 /* A helper function for BINOP_SUBSCRIPT.  */
 
-static struct value *
+struct value *
 eval_op_subscript (struct type *expect_type, struct expression *exp,
 		   enum noside noside, enum exp_opcode op,
 		   struct value *arg1, struct value *arg2)
@@ -3536,6 +3536,39 @@ var_msym_value_operation::evaluate_for_sizeof (struct expression *exp,
   return value_from_longest (size_type, TYPE_LENGTH (type));
 }
 
+value *
+subscript_operation::evaluate_for_sizeof (struct expression *exp,
+					  enum noside noside)
+{
+  if (noside == EVAL_NORMAL)
+    {
+      value *val = std::get<0> (m_storage)->evaluate (nullptr, exp,
+						      EVAL_AVOID_SIDE_EFFECTS);
+      struct type *type = check_typedef (value_type (val));
+      if (type->code () == TYPE_CODE_ARRAY)
+	{
+	  type = check_typedef (TYPE_TARGET_TYPE (type));
+	  if (type->code () == TYPE_CODE_ARRAY)
+	    {
+	      type = type->index_type ();
+	      /* Only re-evaluate the right hand side if the resulting type
+		 is a variable length type.  */
+	      if (type->bounds ()->flag_bound_evaluated)
+		{
+		  val = evaluate (nullptr, exp, EVAL_NORMAL);
+		  /* FIXME: This should be size_t.  */
+		  struct type *size_type
+		    = builtin_type (exp->gdbarch)->builtin_int;
+		  return value_from_longest
+		    (size_type, (LONGEST) TYPE_LENGTH (value_type (val)));
+		}
+	    }
+	}
+    }
+
+  return operation::evaluate_for_sizeof (exp, noside);
+}
+
 }
 
 /* Evaluate a subexpression of EXP, at index *POS, and return a value
diff --git a/gdb/expop.h b/gdb/expop.h
index 4624c2fdefe..5c3b0afee55 100644
--- a/gdb/expop.h
+++ b/gdb/expop.h
@@ -100,6 +100,11 @@ extern struct value *eval_op_binary (struct type *expect_type,
 				     struct expression *exp,
 				     enum noside noside, enum exp_opcode op,
 				     struct value *arg1, struct value *arg2);
+extern struct value *eval_op_subscript (struct type *expect_type,
+					struct expression *exp,
+					enum noside noside, enum exp_opcode op,
+					struct value *arg1,
+					struct value *arg2);
 
 namespace expr
 {
@@ -1112,6 +1117,17 @@ using bitwise_ior_operation
 using bitwise_xor_operation
      = usual_ax_binop_operation<BINOP_BITWISE_XOR, eval_op_binary>;
 
+class subscript_operation
+  : public usual_ax_binop_operation<BINOP_SUBSCRIPT, eval_op_subscript>
+{
+public:
+  using usual_ax_binop_operation<BINOP_SUBSCRIPT,
+				 eval_op_subscript>::usual_ax_binop_operation;
+
+  value *evaluate_for_sizeof (struct expression *exp,
+			      enum noside noside) override;
+};
+
 } /* namespace expr */
 
 #endif /* EXPOP_H */