[PATCH 117/203] Introduce assign_operation

Tom Tromey
2021-01-01T21:48:52Z

This adds class assign_operation, which implements BINOP_ASSIGN.

gdb/ChangeLog
2021-01-01 Tom Tromey <tom@tromey.com>

* expop.h (class assign_operation): New.
* ax-gdb.c (assign_operation::do_generate_ax): New method.
---
gdb/ChangeLog | 5 +++++
gdb/ax-gdb.c | 30 ++++++++++++++++++++++++++++++
gdb/expop.h | 43 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 78 insertions(+)

diff --git a/gdb/ax-gdb.c b/gdb/ax-gdb.c
index 98edc6c0727..d8b5ed78a40 100644
--- 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 e172e11a828..5acbca3db61 100644
--- a/gdb/expop.h
+++ b/gdb/expop.h
@@ -1746,6 +1746,49 @@ class type_instance_operation
{ 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 */
--
2.26.2