Introduce assign_operation

This adds class assign_operation, which implements BINOP_ASSIGN.

gdb/ChangeLog
2021-03-08  Tom Tromey  <tom@tromey.com>

	* expop.h (class assign_operation): New.
	* ax-gdb.c (assign_operation::do_generate_ax): New method.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 58ada4e328222278a0b1b7e4647ffca20d36218a..6bf3cbf4594297c153f2e0785400d43af099ebdb 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2021-03-08  Tom Tromey  <tom@tromey.com>
+
+       * expop.h (class assign_operation): New.
+       * ax-gdb.c (assign_operation::do_generate_ax): New method.
+
 2021-03-08  Tom Tromey  <tom@tromey.com>
 
        * expop.h (class type_instance_operation): New.

diff --git a/gdb/ax-gdb.c b/gdb/ax-gdb.c
index 98edc6c0727a34e08c504696c640e8313a42a368..d8b5ed78a407a9755e40292bed85194257e76d08 100644 (file)
--- a/gdb/ax-gdb.c
+++ b/gdb/ax-gdb.c
@@ -2579,6 +2579,36 @@ op_this_operation::do_generate_ax (struct expression *exp,
           sym->print_name ());
 }
 
+void
+assign_operation::do_generate_ax (struct expression *exp,
+                                 struct agent_expr *ax,
+                                 struct axs_value *value,
+                                 struct type *cast_type)
+{
+  operation *subop = std::get<0> (m_storage).get ();
+  if (subop->opcode () != OP_INTERNALVAR)
+    error (_("May only assign to trace state variables"));
+
+  internalvar_operation *ivarop
+    = dynamic_cast<internalvar_operation *> (subop);
+  gdb_assert (ivarop != nullptr);
+
+  const char *name = internalvar_name (ivarop->get_internalvar ());
+  struct trace_state_variable *tsv;
+
+  std::get<1> (m_storage)->generate_ax (exp, ax, value);
+  tsv = find_trace_state_variable (name);
+  if (tsv)
+    {
+      ax_tsv (ax, aop_setv, tsv->number);
+      if (ax->tracing)
+       ax_tsv (ax, aop_tracev, tsv->number);
+    }
+  else
+    error (_("$%s is not a trace state variable, "
+            "may not assign to it"), name);
+}
+
 }
 
 /* This handles the middle-to-right-side of code generation for binary

diff --git a/gdb/expop.h b/gdb/expop.h
index b196de52d0b7047692499a16b7034b66db00d68b..0f223654052e651602e57836814760d7e4e575d7 100644 (file)
--- a/gdb/expop.h
+++ b/gdb/expop.h
@@ -1757,6 +1757,49 @@ public:
   { return TYPE_INSTANCE; }
 };
 
+/* The assignment operator.  */
+class assign_operation
+  : public tuple_holding_operation<operation_up, operation_up>
+{
+public:
+
+  using tuple_holding_operation::tuple_holding_operation;
+
+  value *evaluate (struct type *expect_type,
+                  struct expression *exp,
+                  enum noside noside) override
+  {
+    value *lhs = std::get<0> (m_storage)->evaluate (nullptr, exp, noside);
+    /* Special-case assignments where the left-hand-side is a
+       convenience variable -- in these, don't bother setting an
+       expected type.  This avoids a weird case where re-assigning a
+       string or array to an internal variable could error with "Too
+       many array elements".  */
+    struct type *xtype = (VALUE_LVAL (lhs) == lval_internalvar
+                         ? nullptr
+                         : value_type (lhs));
+    value *rhs = std::get<1> (m_storage)->evaluate (xtype, exp, noside);
+
+    if (noside == EVAL_SKIP || noside == EVAL_AVOID_SIDE_EFFECTS)
+      return lhs;
+    if (binop_user_defined_p (BINOP_ASSIGN, lhs, rhs))
+      return value_x_binop (lhs, rhs, BINOP_ASSIGN, OP_NULL, noside);
+    else
+      return value_assign (lhs, rhs);
+  }
+
+  enum exp_opcode opcode () const override
+  { return BINOP_ASSIGN; }
+
+protected:
+
+  void do_generate_ax (struct expression *exp,
+                      struct agent_expr *ax,
+                      struct axs_value *value,
+                      struct type *cast_type)
+    override;
+};
+
 } /* namespace expr */
 
 #endif /* EXPOP_H */