Version bump

git-svn-id: file://localhost/svn/verilator/trunk/verilator@753 77ca24e4-aefa-0310-84f0-b9a241c72d87

src/V3LifePost.cpp

@@ -0,0 +1,190 @@
+// $Id$
+//*************************************************************************
+// DESCRIPTION: Verilator: AssignPost Variable assignment elimination
+//
+// Code available from: http://www.veripool.com/verilator
+//
+// AUTHORS: Wilson Snyder with Paul Wasson, Duane Gabli
+//
+//*************************************************************************
+//
+// Copyright 2003-2006 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.
+//
+//*************************************************************************
+// LIFE TRANSFORMATIONS:
+//	Build control-flow graph with assignments and var usages
+//	All modules:
+//	    Delete these
+//		ASSIGN(Vdly, a)
+//	    	... {no reads or writes of a after the first write to Vdly}
+//	 	... {no reads of a after the first write to Vdly}
+//		ASSIGNPOST(Vdly,tmp)
+//	    
+//*************************************************************************
+
+#include "config.h"
+#include <stdio.h>
+#include <stdarg.h>
+#include <unistd.h>
+
+#include "V3Global.h"
+#include "V3LifePost.h"
+#include "V3Stats.h"
+#include "V3Ast.h"
+
+//######################################################################
+// LifePost state, as a visitor of each AstNode
+
+class LifePostBaseVisitor : public AstNVisitor {
+protected:
+//    static int debug() { return 9; }
+};
+
+//######################################################################
+// LifePost class functions
+
+class LifePostElimVisitor : public LifePostBaseVisitor {
+private:
+    // NODE STATE
+    // INPUT:
+    //  AstVarScope::user4p()	-> AstVarScope*, If set, replace this varscope with specified new one
+    // STATE
+    // VISITORS
+    virtual void visit(AstVarRef* nodep, AstNUser*) {
+	AstVarScope* vscp = nodep->varScopep();
+	if (!vscp) nodep->v3fatalSrc("Scope not assigned");
+	if (AstVarScope* newvscp = (AstVarScope*)vscp->user4p()) {
+	    UINFO(9, "  Replace "<<nodep<<" to "<<newvscp<<endl);
+	    AstVarRef* newrefp = new AstVarRef(nodep->fileline(), newvscp, nodep->lvalue());
+	    nodep->replaceWith(newrefp);
+	    nodep->deleteTree(); nodep=NULL;
+	}
+    }
+    virtual void visit(AstModule* nodep, AstNUser*) {
+	// Only track the top scopes, not lower level functions
+	if (nodep->isTop()) nodep->iterateChildren(*this);
+    }
+    virtual void visit(AstCCall* nodep, AstNUser*) {
+	nodep->iterateChildren(*this);
+	// Enter the function and trace it
+	nodep->funcp()->accept(*this);
+    }
+    virtual void visit(AstVar*, AstNUser*) {}	// Don't want varrefs under it
+    virtual void visit(AstNode* nodep, AstNUser*) {
+	nodep->iterateChildren(*this);
+    }
+public:
+    // CONSTRUCTORS
+    LifePostElimVisitor(AstTopScope* nodep) {
+	nodep->accept(*this);
+    }
+    virtual ~LifePostElimVisitor() {}
+};
+
+//######################################################################
+// LifePostlicate delay elimination
+
+class LifePostDlyVisitor : public LifePostBaseVisitor {
+private:
+    // NODE STATE
+    // Cleared on entire tree
+    //  AstVarScope::user()	-> Sequence # of first virtex setting this var.
+    //  AstVarScope::user2()	-> Sequence # of last consumption of this var
+    //  AstVarScope::user4()	-> AstVarScope*: Passed to LifePostElim to substitute this var
+
+    // STATE
+    uint32_t		m_sequence;	// Sequence number of assignments/varrefs
+    V3Double0		m_statAssnDel;	// Statistic tracking
+
+    // VISITORS
+    virtual void visit(AstTopScope* nodep, AstNUser*) {
+	AstNode::userClearTree();	// userp() used on entire tree
+	AstNode::user2ClearTree();	// userp() used on entire tree
+	AstNode::user3ClearTree();	// userp() used on entire tree
+	AstNode::user4ClearTree();	// userp() used on entire tree
+	m_sequence = 0;
+	nodep->iterateChildren(*this);
+
+	// Replace any node4p varscopes with the new scope
+	LifePostElimVisitor visitor (nodep);
+    }
+
+    virtual void visit(AstVarRef* nodep, AstNUser*) {
+	// Consumption/generation of a variable, 
+	AstVarScope* vscp = nodep->varScopep();
+	if (!vscp) nodep->v3fatalSrc("Scope not assigned");
+	m_sequence++;
+	if (nodep->lvalue()) {
+	    // First generator
+	    if (!vscp->user()) vscp->user(m_sequence);
+	} else {
+	    // Last consumer
+	    vscp->user2(m_sequence);
+	}
+    }
+    virtual void visit(AstAssignPost* nodep, AstNUser*) {
+	if (AstVarRef* lhsp = nodep->lhsp()->castVarRef()) {
+	    if (AstVarRef* rhsp = nodep->rhsp()->castVarRef()) {
+		// Scrunch these:
+		//    __Vdly__q = __PVT__clk_clocks;
+		//    ... {no reads or writes of __PVT__q after the first write to __Vdly__q}
+		//    ... {no reads of __Vdly__q after the first write to __Vdly__q}
+		//    __PVT__q = __Vdly__q;
+		UINFO(9,"   POST "<<nodep<<endl);
+		UINFO(9,"     lhs "<<lhsp<<endl);
+		UINFO(9,"     rhs "<<rhsp<<endl);
+		uint32_t firstWrite = rhsp->varScopep()->user();
+		uint32_t lastRead   = rhsp->varScopep()->user2();
+		uint32_t lastRead2  = lhsp->varScopep()->user2();
+		UINFO(9,"     first "<<firstWrite<<" last "<<lastRead<<" "<<lastRead2<<endl);
+		if (lastRead < firstWrite
+		    && lastRead2 < firstWrite) {
+		    UINFO(4,"    DELETE "<<nodep<<endl);
+		    // Mark so LifePostElimVisitor will get it
+		    rhsp->varScopep()->user4p(lhsp->varScopep());
+		    nodep->unlinkFrBack()->deleteTree(); nodep=NULL;
+		    m_statAssnDel++;
+		}
+	    }
+	}
+    }
+    virtual void visit(AstModule* nodep, AstNUser*) {
+	// Only track the top scopes, not lower level functions
+	if (nodep->isTop()) nodep->iterateChildren(*this);
+    }
+    virtual void visit(AstCCall* nodep, AstNUser*) {
+	nodep->iterateChildren(*this);
+	// Enter the function and trace it
+	nodep->funcp()->accept(*this);
+    }
+
+    //-----
+    virtual void visit(AstVar*, AstNUser*) {}	// Don't want varrefs under it
+    virtual void visit(AstNode* nodep, AstNUser*) {
+	nodep->iterateChildren(*this);
+    }
+public:
+    // CONSTRUCTORS
+    LifePostDlyVisitor(AstNetlist* nodep) {
+	nodep->accept(*this);
+    }
+    virtual ~LifePostDlyVisitor() {
+	V3Stats::addStat("Optimizations, Lifetime postassign deletions", m_statAssnDel);
+    }
+};
+
+//######################################################################
+// LifePost class functions
+
+void V3LifePost::lifepostAll(AstNetlist* nodep) {
+    UINFO(2,__FUNCTION__<<": "<<endl);
+    // Mark redundant AssignPost
+    LifePostDlyVisitor visitor (nodep);
+}