Version bump

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

src/V3Depth.cpp

@@ -0,0 +1,155 @@
+// $Id$
+//*************************************************************************
+// DESCRIPTION: Verilator: Prevent very deep expressions
+//
+// 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.
+//
+//*************************************************************************
+// V3Depth's Transformations:
+//		
+// Each module:
+//	For each wide OP, assign a temporary variable.
+//	For each deep expression, assign expression to temporary.
+//
+//*************************************************************************
+
+#include "config.h"
+#include <stdio.h>
+#include <stdarg.h>
+#include <unistd.h>
+#include <algorithm>
+
+#include "V3Global.h"
+#include "V3Depth.h"
+#include "V3Ast.h"
+
+//######################################################################
+// Depth state, as a visitor of each AstNode
+
+class DepthVisitor : public AstNVisitor {
+private:
+    // NODE STATE
+
+    // STATE
+    AstModule*		m_modp;		// Current module
+    AstCFunc*		m_funcp;	// Current block
+    AstNode*		m_stmtp;	// Current statement
+    int			m_depth;	// How deep in an expression
+    int			m_maxdepth;	// Maximum depth in an expression
+
+    //int debug() { return 9; }
+
+    // MSVC++ has a limit of 100 parenthesis.  We have some operator
+    // defines that use 2 parens.  Thus we can't have a expression deeper
+    // then 50 operators.  We'll add some margin though.
+    enum en { MAX_EXPR_DEPTH = 40 };	// Expressions deeper then this need temp
+
+    // METHODS
+    void createDeepTemp(AstNode* nodep) {
+	UINFO(6,"  Deep  "<<nodep<<endl);
+	//if (debug()>=9) nodep->dumpTree(cout,"deep:");
+
+	string newvarname = ((string)"__Vdeeptemp__"+cvtToStr(m_modp->varNumGetInc()));
+	AstVar* varp = new AstVar (nodep->fileline(), AstVarType::STMTTEMP, newvarname,
+				   // Width, not widthMin, as we may be in middle of BITSEL expression which
+				   // though it's one bit wide, needs the mask in the upper bits.
+				   // (Someday we'll have a valid bitmask instead of widths....)
+				   new AstRange(nodep->fileline(), nodep->width()-1, 0));
+	m_funcp->addInitsp(varp);
+	// Replace node tree with reference to var
+	AstVarRef* newp = new AstVarRef (nodep->fileline(), varp, false);
+	nodep->replaceWith(newp);
+	// Put assignment before the referencing statement
+	AstAssign* assp = new AstAssign (nodep->fileline(),
+					 new AstVarRef(nodep->fileline(), varp, true),
+					 nodep);
+	AstNRelinker linker2;
+	m_stmtp->unlinkFrBack(&linker2);
+	assp->addNext(m_stmtp);
+	linker2.relink(assp);
+    }
+
+    // VISITORS
+    virtual void visit(AstModule* nodep, AstNUser*) {
+	UINFO(4," MOD   "<<nodep<<endl);
+	m_modp = nodep;
+	m_funcp = NULL;
+	nodep->iterateChildren(*this);
+    }
+    virtual void visit(AstCFunc* nodep, AstNUser*) {
+	m_funcp = nodep;
+	m_depth = 0;
+	m_maxdepth = 0;
+	nodep->iterateChildren(*this);
+    }
+    virtual void visit(AstNodeStmt* nodep, AstNUser*) {
+	m_depth = 0;
+	m_maxdepth = 0;
+	m_stmtp = nodep;
+	nodep->iterateChildren(*this);
+	m_stmtp = NULL;
+    }
+    // Operators
+    virtual void visit(AstNodeTermop* nodep, AstNUser*) {
+    }
+    virtual void visit(AstNodeMath* nodep, AstNUser*) {
+	m_depth++;
+	if (m_depth>m_maxdepth) m_maxdepth=m_depth;
+	nodep->iterateChildren(*this); 
+	m_depth--;
+
+	if ((m_maxdepth-m_depth) > MAX_EXPR_DEPTH
+	    && m_stmtp
+	    && !nodep->backp()->castNodeStmt()  // Not much point if we're about to use it
+	    ) {
+	    m_maxdepth = m_depth;
+	    createDeepTemp(nodep);
+	}
+    }
+
+    //--------------------
+    // 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
+    DepthVisitor(AstNode* nodep) {
+	m_modp=NULL;
+	m_funcp=NULL;
+	m_stmtp=NULL;
+	m_depth=0;
+	m_maxdepth=0;
+	//
+	AstNode::userClearTree();	// userp() used on entire tree
+	nodep->accept(*this);
+    }
+    virtual ~DepthVisitor() {}
+};
+
+//----------------------------------------------------------------------
+// Top loop
+
+//######################################################################
+// Depth class functions
+
+void V3Depth::depthAll(AstNetlist* nodep) {
+    UINFO(2,__FUNCTION__<<": "<<endl);
+    // We must do it in bottom-up module
+    DepthVisitor visitor (nodep);
+}