From 4892e93a093726bf986ad2d261cf53593354c0c8 Mon Sep 17 00:00:00 2001
From: Stephen Williams <steve@icarus.com>
Date: Sat, 15 Nov 2008 21:42:02 -0800
Subject: [PATCH] Fix special case that one of the arguments of a compare is a
 real expression.

If one of the arguments of a comparison expression has a real value, then
the expression with is 1 no matter the width of the other argument. This
means that the arguments may have different widths in this special case.
Patch is from pr2251119, suggested by Martin Whitaker.
---
 elab_expr.cc | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/elab_expr.cc b/elab_expr.cc
index 5240f2b42..e4c998ff5 100644
--- a/elab_expr.cc
+++ b/elab_expr.cc
@@ -749,20 +749,26 @@ NetExpr* PEBComp::elaborate_expr(Design*des, NetScope*scope,
 	    left_width = left_->test_width(des, scope, 0, 0, left_type, unsized_flag);
 
 	/* Width of operands is self-determined. */
-      int use_wid = left_width;
-      if (right_width > left_width)
-	    use_wid = right_width;
+
+      int use_wid_l = left_width;
+      if (type_is_vectorable(left_type) && (right_width > left_width))
+	    use_wid_l = right_width;
+
+      int use_wid_r = right_width;
+      if (type_is_vectorable(right_type) && (left_width > right_width))
+	    use_wid_r = left_width;
 
       if (debug_elaborate) {
 	    cerr << get_fileline() << ": debug: "
 		 << "Comparison expression operands are "
 		 << left_width << " bits and "
 		 << right_width << " bits. Resorting to "
-		 << use_wid << " bits." << endl;
+		 << use_wid_l << " bits and "
+		 << use_wid_r << " bits." << endl;
       }
 
-      NetExpr*lp = left_->elaborate_expr(des, scope, use_wid, false);
-      NetExpr*rp = right_->elaborate_expr(des, scope, use_wid, false);
+      NetExpr*lp = left_->elaborate_expr(des, scope, use_wid_l, false);
+      NetExpr*rp = right_->elaborate_expr(des, scope, use_wid_r, false);
       if ((lp == 0) || (rp == 0)) {
 	    delete lp;
 	    delete rp;
@@ -775,12 +781,12 @@ NetExpr* PEBComp::elaborate_expr(Design*des, NetScope*scope,
 	// pad the width here. This matters because if the arguments
 	// are signed, then this padding will do sign extension.
       if (type_is_vectorable(lp->expr_type()))
-	    lp = pad_to_width(lp, use_wid);
+	    lp = pad_to_width(lp, use_wid_l);
       if (type_is_vectorable(rp->expr_type()))
-	    rp = pad_to_width(rp, use_wid);
+	    rp = pad_to_width(rp, use_wid_r);
 
-      eval_expr(lp, use_wid);
-      eval_expr(rp, use_wid);
+      eval_expr(lp, use_wid_l);
+      eval_expr(rp, use_wid_r);
 
 	// Handle some operand-specific special cases...
       switch (op_) {