From 930e04f6c77a8b2a7cbf656d2f900ee6a8645b55 Mon Sep 17 00:00:00 2001
From: Nick Gasson <nick@nickg.me.uk>
Date: Tue, 1 Jul 2008 11:28:02 +0100
Subject: [PATCH] Ensure port map expressions are globally static

---
 tgt-vhdl/scope.cc       | 32 ++++++++++++++++++++++++++++++--
 tgt-vhdl/vhdl_syntax.hh |  3 +++
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/tgt-vhdl/scope.cc b/tgt-vhdl/scope.cc
index b33f14c1f..0b7bce50d 100644
--- a/tgt-vhdl/scope.cc
+++ b/tgt-vhdl/scope.cc
@@ -313,9 +313,37 @@ static void map_signal(ivl_signal_t to, vhdl_entity *parent,
    ivl_nexus_t nexus = ivl_signal_nex(to, 0);
 
    vhdl_expr *to_e = nexus_to_expr(parent->get_arch()->get_scope(), nexus, to);
-   std::cout << "map " << ivl_signal_basename(to) << std::endl;
-   inst->map_port(ivl_signal_basename(to), to_e);
 
+   // The expressions in a VHDL port map must be 'globally static'
+   // i.e. they can't be arbitrary expressions
+   // To handle this, only vhdl_var_refs are mapped automatically
+   // Otherwise a temporary variable is created to store the
+   // result of the expression and that is mapped to the port
+   // This is actually a bit stricter than necessary: but turns out
+   // to be much easier to implement
+   const char *basename = ivl_signal_basename(to);
+   vhdl_var_ref *to_ref;
+   if ((to_ref = dynamic_cast<vhdl_var_ref*>(to_e))) {
+      inst->map_port(basename, to_ref);
+   }
+   else {
+      // Not a static expression
+      std::string tmpname(inst->get_inst_name().c_str());
+      tmpname += "_";
+      tmpname += basename;
+      tmpname += "_Expr";
+      
+      vhdl_type *tmptype = new vhdl_type(*to_e->get_type());
+      parent->get_arch()->get_scope()->add_decl
+         (new vhdl_signal_decl(tmpname.c_str(), tmptype));
+
+      vhdl_var_ref *tmp_ref1 = new vhdl_var_ref(tmpname.c_str(), NULL);
+      parent->get_arch()->add_stmt(new vhdl_cassign_stmt(tmp_ref1, to_e));
+
+      vhdl_var_ref *tmp_ref2 = new vhdl_var_ref(*tmp_ref1);
+      inst->map_port(basename, tmp_ref2);
+   }
+   
    return;
    
    /*   int nptrs = ivl_nexus_ptrs(nexus);
diff --git a/tgt-vhdl/vhdl_syntax.hh b/tgt-vhdl/vhdl_syntax.hh
index 2487840ed..c87eea284 100644
--- a/tgt-vhdl/vhdl_syntax.hh
+++ b/tgt-vhdl/vhdl_syntax.hh
@@ -522,6 +522,9 @@ public:
 
    void emit(std::ostream &of, int level) const;
    void map_port(const char *name, vhdl_expr *expr);
+
+   const std::string &get_comp_name() const { return comp_name_; }
+   const std::string &get_inst_name() const { return inst_name_; }
 private:
    std::string comp_name_, inst_name_;
    port_map_list_t mapping_;