From 4c8a7b221c531d53c25c1c454846356d64e45089 Mon Sep 17 00:00:00 2001
From: Stephen Williams <steve@icarus.com>
Date: Mon, 17 Dec 2007 21:00:18 -0800
Subject: [PATCH] Proper padding of constant bitwise operands

When evaluating bitwise binary expressions at compile time, get the
signed/unsigned padding correct. Pay special attention to the case
of $signed/$unsigned  changing the signedness of the operand.
---
 eval_tree.cc | 11 +++++++++++
 netlist.cc   |  2 +-
 netlist.h    |  5 +++--
 set_width.cc |  6 ++++++
 4 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/eval_tree.cc b/eval_tree.cc
index 2f2e877cc..19558bbdc 100644
--- a/eval_tree.cc
+++ b/eval_tree.cc
@@ -248,6 +248,17 @@ NetEConst* NetEBBits::eval_tree(int prune_to_width)
       if (rwid > wid)
 	    rwid = wid;
 
+	// Sub-expressions of bitwise operators need to be the same
+	// width. Pad them out if necessary.
+      if (lwid < wid) {
+	    lval = pad_to_width(lval, wid);
+	    lwid = wid;
+      }
+      if (rwid < wid) {
+	    rval = pad_to_width(rval, wid);
+	    rwid = wid;
+      }
+
       switch (op()) {
 
 	  case '|': {
diff --git a/netlist.cc b/netlist.cc
index 97e328b80..9321eaeae 100644
--- a/netlist.cc
+++ b/netlist.cc
@@ -2002,7 +2002,7 @@ NetEBLogic* NetEBLogic::dup_expr() const
 NetEConst::NetEConst(const verinum&val)
 : NetExpr(val.len()), value_(val)
 {
-      cast_signed(value_.has_sign());
+      cast_signed_base_(value_.has_sign());
 }
 
 NetEConst::~NetEConst()
diff --git a/netlist.h b/netlist.h
index 9f1ec6d98..022187df3 100644
--- a/netlist.h
+++ b/netlist.h
@@ -1103,7 +1103,7 @@ class NetExpr  : public LineInfo {
 	// This method returns true if the expression is
 	// signed. Unsigned expressions return false.
       bool has_sign() const;
-      void cast_signed(bool flag);
+      virtual void cast_signed(bool flag);
 
 	// This returns true if the expression has a definite
 	// width. This is generally true, but in some cases the
@@ -1145,6 +1145,7 @@ class NetExpr  : public LineInfo {
 
     protected:
       void expr_width(unsigned w) { width_ = w; }
+      void cast_signed_base_(bool flag) {signed_flag_ = flag; }
 
     private:
       unsigned width_;
@@ -1169,7 +1170,7 @@ class NetEConst  : public NetExpr {
       const verinum&value() const;
 
       virtual bool set_width(unsigned w, bool last_chance =false);
-
+      virtual void cast_signed(bool sign_flag);
       virtual bool has_width() const;
       virtual ivl_variable_type_t expr_type() const;
 
diff --git a/set_width.cc b/set_width.cc
index e293ca192..c15b9521b 100644
--- a/set_width.cc
+++ b/set_width.cc
@@ -326,6 +326,12 @@ bool NetEConst::set_width(unsigned w, bool last_chance)
       }
 }
 
+void NetEConst::cast_signed(bool sign_flag)
+{
+      value_.has_sign(sign_flag);
+      cast_signed_base_(sign_flag);
+}
+
 /*
  * Parameter vectors cannot be resized because they refer to a common
  * value.