From 621c51589a948ff31b6376b2262d742a5a82ba6c Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Sun, 4 May 2014 08:50:44 -0400
Subject: [PATCH] Fix shift by x, bug760.

---
 src/V3Const.cpp               | 3 +++
 test_regress/t/t_math_shift.v | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/src/V3Const.cpp b/src/V3Const.cpp
index 559094077..90a4e96c4 100644
--- a/src/V3Const.cpp
+++ b/src/V3Const.cpp
@@ -234,16 +234,19 @@ private:
     }
     bool operandHugeShiftL(AstNodeBiop* nodep) {
 	return (nodep->rhsp()->castConst()
+		&& !nodep->rhsp()->castConst()->num().isFourState()
 		&& nodep->rhsp()->castConst()->toUInt() >= (uint32_t)(nodep->width())
 		&& isTPure(nodep->lhsp()));
     }
     bool operandHugeShiftR(AstNodeBiop* nodep) {
 	return (nodep->rhsp()->castConst()
+		&& !nodep->rhsp()->castConst()->num().isFourState()
 		&& nodep->rhsp()->castConst()->toUInt() >= (uint32_t)(nodep->lhsp()->width())
 		&& isTPure(nodep->lhsp()));
     }
     bool operandIsTwo(AstNode* nodep) {
 	return (nodep->castConst()
+		&& !nodep->castConst()->num().isFourState()
 		&& nodep->width() <= VL_QUADSIZE
 		&& nodep->castConst()->toUQuad()==2);
     }
diff --git a/test_regress/t/t_math_shift.v b/test_regress/t/t_math_shift.v
index 796c7403b..0770fd431 100644
--- a/test_regress/t/t_math_shift.v
+++ b/test_regress/t/t_math_shift.v
@@ -4,11 +4,14 @@
 // without warranty, 2004 by Wilson Snyder.
 
 module t (/*AUTOARG*/
+   // Outputs
+   ign,
    // Inputs
    clk
    );
 
    input clk;
+   output [31:0] ign;
 
    reg [31:0] 		right;
    reg [31:0] 		left;
@@ -16,6 +19,8 @@ module t (/*AUTOARG*/
    reg [63:0] 		qleft;
    reg [31:0] 		amt;
 
+   assign ign = {31'h0, clk} >>> 4'bx;  // bug760
+
    always @* begin
       right = 32'h819b018a >> amt;
       left  = 32'h819b018a << amt;