From d3049d9c89eb55c9b88ca250c47e4fa4eb1a933a Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Thu, 15 May 2014 21:49:43 -0400
Subject: [PATCH] Fix huge shifts to zero with -Wno-WIDTH, bug766.

---
 Changes                         |  2 +-
 src/V3Number.cpp                | 16 ++++++++++++----
 src/V3Number.h                  |  9 ++++++++-
 test_regress/t/t_math_signed5.v |  7 +++++++
 4 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/Changes b/Changes
index c65dd7ae9..de6a843b5 100644
--- a/Changes
+++ b/Changes
@@ -9,7 +9,7 @@ indicates the contributor was also the author of the fix; Thanks!
 
 ***   Support SV 2012 package import before port list.
 
-****  Fix huge shifts to zero with -Wno-WIDTH, bug765. [Clifford Wolf]
+****  Fix huge shifts to zero with -Wno-WIDTH, bug765, bug766. [Clifford Wolf]
 
 ****  Fix gate primitives with arrays and non-arrayed pins.
 
diff --git a/src/V3Number.cpp b/src/V3Number.cpp
index c8ca9717d..857181875 100644
--- a/src/V3Number.cpp
+++ b/src/V3Number.cpp
@@ -1125,8 +1125,10 @@ V3Number& V3Number::opShiftR (const V3Number& lhs, const V3Number& rhs) {
     if (rhs.isFourState()) return setAllBitsX();
     setZero();
     uint32_t rhsval = rhs.toUInt();
-    for (int bit=0; bit<this->width(); bit++) {
-	setBit(bit,lhs.bitIs(bit + rhsval));
+    if (rhsval < (uint32_t)lhs.width()) {
+	for (int bit=0; bit<this->width(); bit++) {
+	    setBit(bit,lhs.bitIs(bit + rhsval));
+	}
     }
     return *this;
 }
@@ -1138,8 +1140,14 @@ V3Number& V3Number::opShiftRS (const V3Number& lhs, const V3Number& rhs) {
     if (rhs.isFourState()) return setAllBitsX();
     setZero();
     uint32_t rhsval = rhs.toUInt();
-    for (int bit=0; bit<this->width(); bit++) {
-	setBit(bit,lhs.bitIsExtend(bit + rhsval));
+    if (rhsval < (uint32_t)lhs.width()) {
+	for (int bit=0; bit<this->width(); bit++) {
+	    setBit(bit,lhs.bitIsExtend(bit + rhsval));
+	}
+    } else {
+	for (int bit=0; bit<this->width(); bit++) {
+	    setBit(bit,lhs.bitIsExtend(lhs.width()-1));
+	}
     }
     return *this;
 }
diff --git a/src/V3Number.h b/src/V3Number.h
index 2caba3e20..c0940cf23 100644
--- a/src/V3Number.h
+++ b/src/V3Number.h
@@ -60,13 +60,14 @@ public:
     }
 private:
     char bitIs	(int bit) const {
-	if (bit>=m_width) {
+	if (bit>=m_width || bit<0) {
 	    // We never sign extend
 	    return '0';
 	}
 	return ( "01zx"[(((m_value[bit/32] & (1UL<<(bit&31)))?1:0)
 			 | ((m_valueX[bit/32] & (1UL<<(bit&31)))?2:0))] ); }
     char bitIsExtend (int bit) const {
+	if (bit<0) return '0';
 	if (bit>=m_width) {
 	    bit = m_width-1;
 	    // We do sign extend
@@ -76,22 +77,28 @@ private:
 	return ( "01zx"[(((m_value[bit/32] & (1UL<<(bit&31)))?1:0)
 			 | ((m_valueX[bit/32] & (1UL<<(bit&31)))?2:0))] ); }
     bool bitIs0	(int bit) const {
+	if (bit<0) return false;
 	if (bit>=m_width) return !bitIsXZ(m_width-1);
 	return ( (m_value[bit/32] & (1UL<<(bit&31)))==0 && !(m_valueX[bit/32] & (1UL<<(bit&31))) ); }
     bool bitIs1	(int bit) const {
+	if (bit<0) return false;
 	if (bit>=m_width) return false;
 	return ( (m_value[bit/32] & (1UL<<(bit&31))) && !(m_valueX[bit/32] & (1UL<<(bit&31))) ); }
     bool bitIs1Extend (int bit) const {
+	if (bit<0) return false;
 	if (bit>=m_width) return bitIs1Extend(m_width-1);
 	return ( (m_value[bit/32] & (1UL<<(bit&31))) && !(m_valueX[bit/32] & (1UL<<(bit&31))) ); }
     bool bitIsX (int bit) const {
+	if (bit<0) return false;
 	if (bit>=m_width) return bitIsZ(m_width-1);
 	return ( (m_value[bit/32] & (1UL<<(bit&31))) && (m_valueX[bit/32] & (1UL<<(bit&31))) ); }
     bool bitIsXZ(int bit) const {
+	if (bit<0) return false;
 	if (bit>=m_width) return bitIsXZ(m_width-1);
 	return ( (m_valueX[bit/32] & (1UL<<(bit&31))) && 1);
     }
     bool bitIsZ (int bit) const {
+	if (bit<0) return false;
 	if (bit>=m_width) return bitIsZ(m_width-1);
 	return ( (~m_value[bit/32] & (1UL<<(bit&31))) && (m_valueX[bit/32] & (1UL<<(bit&31))) ); }
     uint32_t bitsValue(int lsb, int nbits) const {
diff --git a/test_regress/t/t_math_signed5.v b/test_regress/t/t_math_signed5.v
index ec90fd8ac..a93c74307 100644
--- a/test_regress/t/t_math_signed5.v
+++ b/test_regress/t/t_math_signed5.v
@@ -15,6 +15,8 @@
    reg [2:0] 	    w3_u;
    reg [3:0] 	    w4_u;
    reg [4:0] 	    w5_u;
+   reg [15:0] 	    w16a_u;
+   reg [15:0] 	    w16_u;
    real 	    r;
 
    reg signed [4:0] bug754_a;
@@ -116,6 +118,11 @@
       w4_u = (w3_u >> 2'b11) >> 1;
       `checkh(w4_u, 4'b0000);
 
+      // bug766
+      w16a_u = 16'h1234;
+      w16_u = (w16a_u >> 16) >>> 32'h7ffffff1;
+      `checkh(w16_u, 16'h0000);
+
       if (fail) $stop;
       $write("*-* All Finished *-*\n");
       $finish;