From 5a4e4b2dcda1c7e16ab6a583b25cc3055671a647 Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Wed, 10 Mar 2021 17:47:31 -0500
Subject: [PATCH] Add -Oo to disable const bit tree (#2830).

---
 src/V3Const.cpp   | 1 +
 src/V3Options.cpp | 4 +++-
 src/V3Options.h   | 2 ++
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/V3Const.cpp b/src/V3Const.cpp
index b6b528bc0..d12bb2a40 100644
--- a/src/V3Const.cpp
+++ b/src/V3Const.cpp
@@ -687,6 +687,7 @@ private:
         return true;
     }
     bool matchBitOpTree(AstNode* nodep) {
+        if (!v3Global.opt.oConstBitOpTree()) return false;
         AstNode* newp = nullptr;
         bool tried = false;
         if (AstAnd* andp = VN_CAST(nodep, And)) {  // 1 & BitOpTree
diff --git a/src/V3Options.cpp b/src/V3Options.cpp
index 1dbb7bd7d..c54149d81 100644
--- a/src/V3Options.cpp
+++ b/src/V3Options.cpp
@@ -1159,7 +1159,8 @@ void V3Options::parseOptsList(FileLine* fl, const string& optdir, int argc, char
                     case 'k': m_oSubstConst = flag; break;
                     case 'l': m_oLife = flag; break;
                     case 'm': m_oAssemble = flag; break;
-                    //    n o
+                    //    n
+                    case 'o': m_oConstBitOpTree = flag; break;  // Can remove ~2022-01 when stable
                     case 'p':
                         m_public = !flag;
                         break;  // With -Op so flag=0, we want public on so few optimizations done
@@ -1864,6 +1865,7 @@ void V3Options::optimize(int level) {
     m_oCase = flag;
     m_oCombine = flag;
     m_oConst = flag;
+    m_oConstBitOpTree = flag;
     m_oDedupe = flag;
     m_oExpand = flag;
     m_oGate = flag;
diff --git a/src/V3Options.h b/src/V3Options.h
index 00b9f156c..4db85011a 100644
--- a/src/V3Options.h
+++ b/src/V3Options.h
@@ -341,6 +341,7 @@ private:
     bool        m_oCase;        // main switch: -Oe: case tree conversion
     bool        m_oCombine;     // main switch: -Ob: common icode packing
     bool        m_oConst;       // main switch: -Oc: constant folding
+    bool        m_oConstBitOpTree;  // main switch: -Oo: constant bit op tree
     bool        m_oDedupe;      // main switch: -Od: logic deduplication
     bool        m_oExpand;      // main switch: -Ox: expansion of C macros
     bool        m_oGate;        // main switch: -Og: gate wire elimination
@@ -563,6 +564,7 @@ public:
     bool oCase() const { return m_oCase; }
     bool oCombine() const { return m_oCombine; }
     bool oConst() const { return m_oConst; }
+    bool oConstBitOpTree() const { return m_oConstBitOpTree; }
     bool oDedupe() const { return m_oDedupe; }
     bool oExpand() const { return m_oExpand; }
     bool oGate() const { return m_oGate; }