synth-vhdl_expr: add an hook for signal attributes

2 files changed, 11 insertions, 0 deletions

diff --git a/src/synth/synth-vhdl_expr.adb b/src/synth/synth-vhdl_expr.adb
index ff44a926d..5b5034986 100644
--- a/src/synth/synth-vhdl_expr.adb
+++ b/src/synth/synth-vhdl_expr.adb
@@ -2208,6 +2208,12 @@ package body Synth.Vhdl_Expr is
          when Iir_Kind_Overflow_Literal =>
             Error_Msg_Synth (+Expr, "out of bound expression");
             return No_Valtyp;
+         when Iir_Kind_Event_Attribute =>
+            if Hook_Signal_Attribute /= null then
+               return Hook_Signal_Attribute (Syn_Inst, Expr);
+            end if;
+            Error_Msg_Synth (+Expr, "signal attributes not allowed");
+            return No_Valtyp;
          when others =>
             Error_Kind ("synth_expression_with_type", Expr);
       end case;
diff --git a/src/synth/synth-vhdl_expr.ads b/src/synth/synth-vhdl_expr.ads
index 8f1edd5f3..5c81701c1 100644
--- a/src/synth/synth-vhdl_expr.ads
+++ b/src/synth/synth-vhdl_expr.ads
@@ -90,6 +90,11 @@ package Synth.Vhdl_Expr is
                                         Expr : Node;
                                         Expr_Type : Type_Acc) return Valtyp;
 
+   --  For value signal attribute (like 'Event).
+   type Hook_Signal_Attribute_Acc is access
+     function (Syn_Inst : Synth_Instance_Acc; Expr : Node) return Valtyp;
+   Hook_Signal_Attribute : Hook_Signal_Attribute_Acc;
+
    --  Use base type of EXPR to synthesize EXPR.  Useful when the type of
    --  EXPR is defined by itself or a range.
    function Synth_Expression_With_Basetype (Syn_Inst : Synth_Instance_Acc;