Add isolate_assignments meta comment

git-svn-id: file://localhost/svn/verilator/trunk/verilator@871 77ca24e4-aefa-0310-84f0-b9a241c72d87

src/V3SplitAs.cpp

@@ -0,0 +1,204 @@
+// $Id$
+//*************************************************************************
+// DESCRIPTION: Verilator: Break always into separate statements to reduce temps
+//
+// Code available from: http://www.veripool.com/verilator
+//
+// AUTHORS: Wilson Snyder with Paul Wasson, Duane Gabli
+//
+//*************************************************************************
+//
+// Copyright 2003-2007 by Wilson Snyder.  This program is free software; you can
+// redistribute it and/or modify it under the terms of either the GNU
+// General Public License or the Perl Artistic License.
+//
+// Verilator is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+//*************************************************************************
+// V3SplitAs's Transformations:
+//
+//	Search each ALWAYS for a VARREF lvalue with a /*isolate_asignments*/ attribute
+//	If found, color statements with both, assignment to that varref, or other assignments.
+//	Replicate the Always, and remove mis-colored duplicate code.
+//
+//*************************************************************************
+
+#include "config_build.h"
+#include "verilatedos.h"
+#include <stdio.h>
+#include <stdarg.h>
+#include <unistd.h>
+#include <algorithm>
+#include <vector>
+#include <map>
+
+#include "V3Global.h"
+#include "V3SplitAs.h"
+#include "V3Stats.h"
+#include "V3Ast.h"
+
+//######################################################################
+
+class SplitAsBaseVisitor : public AstNVisitor {
+public:
+    // METHODS
+    //int debug() { return 9; }
+};
+
+//######################################################################
+// Find all split variables in a block
+
+class SplitAsFindVisitor : public SplitAsBaseVisitor {
+private:
+    // STATE
+    AstVarScope* m_splitVscp;	// Variable we want to split
+
+    // METHODS
+    virtual void visit(AstVarRef* nodep, AstNUser*) {
+	if (nodep->lvalue() && !m_splitVscp
+	    && nodep->varp()->attrIsolateAssign()) {
+	    m_splitVscp = nodep->varScopep();
+	}
+    }
+    virtual void visit(AstNode* nodep, AstNUser*) {
+	nodep->iterateChildren(*this);
+    }
+public:
+    // CONSTUCTORS
+    SplitAsFindVisitor(AstAlways* nodep) {
+	m_splitVscp = NULL;
+	nodep->accept(*this);
+    }
+    virtual ~SplitAsFindVisitor() {}
+    // METHODS
+    AstVarScope* splitVscp() const { return m_splitVscp; }
+};
+
+//######################################################################
+// Remove nodes not containing proper references
+
+class SplitAsCleanVisitor : public SplitAsBaseVisitor {
+private:
+    // STATE
+    AstVarScope* m_splitVscp;	// Variable we want to split
+    bool	 m_modeMatch;	// Remove matching Vscp, else non-matching
+    bool	 m_keepStmt;	// Current Statement must be preserved
+    bool	 m_matches;	// Statement below has matching lvalue reference
+
+    // METHODS
+    virtual void visit(AstVarRef* nodep, AstNUser*) {
+	if (nodep->lvalue()) {
+	    if (nodep->varScopep()==m_splitVscp) {
+		UINFO(6,"       CL VAR "<<nodep<<endl);
+		m_matches = true;
+	    }
+	}
+    }
+    virtual void visit(AstNodeStmt* nodep, AstNUser*) {
+	UINFO(6,"     CL STMT "<<nodep<<endl);
+	bool oldKeep = m_keepStmt;
+	{
+	    m_matches = false;
+	    m_keepStmt = false;
+
+	    nodep->iterateChildren(*this);
+
+	    if (m_keepStmt
+		|| (m_modeMatch ? m_matches : !m_matches)) {
+		UINFO(6,"     Keep   STMT "<<nodep<<endl);
+		m_keepStmt = true;
+	    } else {
+		UINFO(6,"     Delete STMT "<<nodep<<endl);
+		nodep->unlinkFrBack(); pushDeletep(nodep);
+	    }
+	}
+	// If something below matches, the upper statement remains too.
+	m_keepStmt = oldKeep || m_keepStmt;
+	UINFO(9,"     upKeep="<<m_keepStmt<<" STMT "<<nodep<<endl);
+    }
+    virtual void visit(AstNode* nodep, AstNUser*) {
+	nodep->iterateChildren(*this);
+    }
+public:
+    // CONSTUCTORS
+    SplitAsCleanVisitor(AstAlways* nodep, AstVarScope* vscp, bool modeMatch) {
+	m_splitVscp = vscp;
+	m_modeMatch = modeMatch;
+	nodep->accept(*this);
+    }
+    virtual ~SplitAsCleanVisitor() {}
+};
+
+//######################################################################
+// SplitAs class functions
+
+class SplitAsVisitor : public SplitAsBaseVisitor {
+private:
+    // NODE STATE
+    //  AstAlways::user()	-> bool.  True if already processed
+
+    // STATE
+    V3Double0	m_statSplits;	// Statistic tracking
+    AstVarScope* m_splitVscp;	// Variable we want to split
+
+    // METHODS
+    void splitAlways(AstAlways* nodep) {
+	UINFO(3,"Split  "<<nodep<<endl);
+	UINFO(3,"   For "<<m_splitVscp<<endl);
+	if (debug()>=9) nodep->dumpTree(cout,"-in  : ");
+	// Duplicate it and link in
+	AstAlways* newp = nodep->cloneTree(false)->castAlways();
+	newp->user(true);  // So we don't clone it again
+	nodep->addNextHere(newp);
+	{   // Delete stuff we don't want in old
+	    SplitAsCleanVisitor visitor (nodep, m_splitVscp, false);
+	    if (debug()>=9) nodep->dumpTree(cout,"-out0: ");
+	}
+	{   // Delete stuff we don't want in new
+	    SplitAsCleanVisitor visitor (newp, m_splitVscp, true);
+	    if (debug()>=9) newp->dumpTree(cout,"-out1: ");
+	}
+    }
+
+    virtual void visit(AstAlways* nodep, AstNUser*) {
+	// Are there any lvalue references below this?
+	// There could be more then one.  So, we process the first one found first.
+	if (!nodep->user()) {
+	    SplitAsFindVisitor visitor (nodep);
+	    m_splitVscp = visitor.splitVscp();
+	    if (m_splitVscp) {
+		splitAlways(nodep);
+		m_statSplits++;
+	    }
+	}
+    }
+
+    // Speedup; no always under math
+    virtual void visit(AstNodeMath* nodep, AstNUser*) {}
+
+    virtual void visit(AstNode* nodep, AstNUser*) {
+	nodep->iterateChildren(*this);
+    }
+
+public:
+    // CONSTUCTORS
+    SplitAsVisitor(AstNetlist* nodep) {
+	m_splitVscp = NULL;
+	AstNode::userClearTree();	// userp() used on entire tree
+	nodep->accept(*this);
+    }
+    virtual ~SplitAsVisitor() {
+	V3Stats::addStat("Optimizations, isolate_assignments blocks", m_statSplits);
+    }
+};
+
+//######################################################################
+// SplitAs class functions
+
+void V3SplitAs::splitAsAll(AstNetlist* nodep) {
+    UINFO(2,__FUNCTION__<<": "<<endl);
+    SplitAsVisitor visitor (nodep);
+}