verilator/src/V3DepthBlock.cpp

// -*- mode: C++; c-file-style: "cc-mode" -*-
//*************************************************************************
// DESCRIPTION: Verilator: Prevent very deep expressions
//
// Code available from: http://www.veripool.org/verilator
//
//*************************************************************************
//
// Copyright 2003-2014 by Wilson Snyder.  This program is free software; you can
// redistribute it and/or modify it under the terms of either the GNU
// Lesser General Public License Version 3 or the Perl Artistic License
// Version 2.0.
//
// 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.
//
//*************************************************************************
// V3DepthBlock's Transformations:
//
// Each module:
//	For each deep block, create cfunc including that block.
//
//*************************************************************************

#include "config_build.h"
#include "verilatedos.h"
#include <cstdio>
#include <cstdarg>
#include <unistd.h>
#include <algorithm>

#include "V3Global.h"
#include "V3DepthBlock.h"
#include "V3Ast.h"
#include "V3EmitCBase.h"

//######################################################################

class DepthBlockVisitor : public AstNVisitor {
private:
    // NODE STATE

    // STATE
    AstNodeModule*	m_modp;		// Current module
    AstCFunc*		m_funcp;	// Current function
    int			m_depth;	// How deep in an expression
    int			m_deepNum;	// How many functions made

    // METHODS
    static int debug() {
	static int level = -1;
	if (VL_UNLIKELY(level < 0)) level = v3Global.opt.debugSrcLevel(__FILE__);
	return level;
    }

    AstCFunc* createDeepFunc(AstNode* nodep) {
	AstNRelinker relinkHandle;
	nodep->unlinkFrBack(&relinkHandle);
	// Create function
	string name = m_funcp->name()+"__deep"+cvtToStr(++m_deepNum);
	AstCFunc* funcp = new AstCFunc(nodep->fileline(), name, NULL);
	funcp->argTypes(EmitCBaseVisitor::symClassVar());
	funcp->symProlog(true);
	funcp->slow(m_funcp->slow());
	funcp->addStmtsp(nodep);
	m_modp->addStmtp(funcp);
	// Call it at the point where the body was removed from
	AstCCall* callp = new AstCCall(nodep->fileline(), funcp);
	callp->argTypes("vlSymsp");
	UINFO(6,"      New "<<callp<<endl);
	//
	relinkHandle.relink(callp);
	return funcp;
    }

    // VISITORS
    virtual void visit(AstNodeModule* nodep, AstNUser*) {
	UINFO(4," MOD   "<<nodep<<endl);
	m_modp = nodep;
	m_deepNum = 0;
	nodep->iterateChildren(*this);
	m_modp = NULL;
    }
    virtual void visit(AstCFunc* nodep, AstNUser*) {
	// We recurse into this.
	int lastDepth = m_depth;
	AstCFunc* lastFuncp = m_funcp;
	{
	    m_depth = 0;
	    m_funcp = nodep;
	    nodep->iterateChildren(*this);
	}
	m_depth = lastDepth;
	m_funcp = lastFuncp;
    }
    void visitStmt(AstNodeStmt* nodep) {
	m_depth++;
	if (m_depth > v3Global.opt.compLimitBlocks()
	    && !nodep->castCCall()) {   // Already done
	    UINFO(4, "DeepBlocks "<<m_depth<<" "<<nodep<<endl);
	    AstNode* backp = nodep->backp();  // Only for debug
	    if (debug()>=9) backp->dumpTree(cout,"-   pre : ");
	    AstCFunc* funcp = createDeepFunc(nodep);
	    funcp->accept(*this);
	    if (debug()>=9) backp->dumpTree(cout,"-   post: ");
	    if (debug()>=9) funcp->dumpTree(cout,"-   func: ");
	} else {
	    nodep->iterateChildren(*this);
	}
	m_depth--;
    }
    virtual void visit(AstNodeStmt* nodep, AstNUser*) {
	visitStmt(nodep);
    }

    virtual void visit(AstNodeMath* nodep, AstNUser*) {}  // Accelerate
    //--------------------
    // Default: Just iterate
    virtual void visit(AstVar* nodep, AstNUser*) {}	// Don't hit varrefs under vars
    virtual void visit(AstNode* nodep, AstNUser*) {
	nodep->iterateChildren(*this);
    }

public:
    // CONSTUCTORS
    DepthBlockVisitor(AstNetlist* nodep) {
	m_modp=NULL;
	m_depth=0;
	//
	nodep->accept(*this);
    }
    virtual ~DepthBlockVisitor() {}
};

//######################################################################
// DepthBlock class functions

void V3DepthBlock::depthBlockAll(AstNetlist* nodep) {
    UINFO(2,__FUNCTION__<<": "<<endl);
    DepthBlockVisitor visitor (nodep);
}