From 6a6995187e8fb582911db60e71efdcaa71ba3b28 Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Thu, 19 Apr 2007 18:20:16 +0000
Subject: [PATCH] Add --compiler flags, and break up deep functions

git-svn-id: file://localhost/svn/verilator/trunk/verilator@913 77ca24e4-aefa-0310-84f0-b9a241c72d87
---
 Changes                       |   6 +-
 bin/verilator                 |  33 +++-
 src/Makefile_obj.in           |   1 +
 src/V3Depth.cpp               |  20 +-
 src/V3DepthBlock.cpp          | 139 ++++++++++++++
 src/V3DepthBlock.h            |  36 ++++
 src/V3Options.cpp             |  32 +++-
 src/V3Options.h               |   7 +
 src/Verilator.cpp             |   7 +
 test_regress/driver.pl        |   2 +
 test_regress/t/t_case_deep.pl |  19 ++
 test_regress/t/t_case_deep.v  | 342 ++++++++++++++++++++++++++++++++++
 test_regress/t/t_func_crc.pl  |   1 +
 test_regress/t/t_if_deep.pl   |  19 ++
 test_regress/t/t_if_deep.v    | 141 ++++++++++++++
 test_regress/t/t_math_imm.pl  |   1 +
 16 files changed, 777 insertions(+), 29 deletions(-)
 create mode 100644 src/V3DepthBlock.cpp
 create mode 100644 src/V3DepthBlock.h
 create mode 100755 test_regress/t/t_case_deep.pl
 create mode 100644 test_regress/t/t_case_deep.v
 create mode 100755 test_regress/t/t_if_deep.pl
 create mode 100644 test_regress/t/t_if_deep.v

diff --git a/Changes b/Changes
index ee9e21639..c2e473987 100644
--- a/Changes
+++ b/Changes
@@ -3,7 +3,11 @@ Revision history for Verilator
 The contributors that suggested a given feature are shown in [].  [by ...]
 indicates the contributor was also the author of the fix; Thanks!
 
-* Verilator 3.64**
+* Verilator 3.65**
+
+**   Add --compiler msvc option.  This is now required when Verilated code
+     is to be run through MSVC++.  This also enables fixing error C1061,
+     blocks nested too deeply.  [Ralf Karge]
 
 **   Add --lint-only option.
 
diff --git a/bin/verilator b/bin/verilator
index 57387e097..8977691a7 100755
--- a/bin/verilator
+++ b/bin/verilator
@@ -246,6 +246,27 @@ output files.
 
 Specifies C++ without SystemC output mode; see also --sc and --sp.
 
+=item --compiler I<compiler-name>
+
+Enables tunings and work-arounds for the specified C++ compiler.
+
+=over 4
+
+=item gcc
+
+Tune for Gnu C++, although generated code should work on almost any
+compliant C++ compiler.  Currently the default.
+
+=item msvc
+
+Tune for Microsoft Visual C++.  This may reduce execution speed as it
+enables several workarounds to avoid silly hardcoded limits in MSVC++.
+This includes breaking deeply nested parenthesized expressions into
+sub-expressions to avoid error C1009, and breaking deep blocks into
+functions to avoid error C1061.
+
+=back
+
 =item --coverage
 
 Enables all forms of coverage, alias for --coverage-line, --coverage-user
@@ -691,11 +712,13 @@ fast path, mostly code that is executed every cycle.  OPT_SLOW specifies
 optimizations for slow-path files (plus tracing), which execute only
 rarely, yet take a long time to compile with optimization on.  OPT
 specifies overall optimization and affects all compiles, including those
-OPT_FAST and OPT_SLOW affect.  For best results, use OPT="-O2".  Nearly the
-same results can be had with much better compile times with OPT_FAST="-O1
--fstrict-aliasing".  Unfortunately, using the optimizer with SystemC files
-can result in compiles taking several minutes.  (The SystemC libraries have
-many little inlined functions that drive the compiler nuts.)
+OPT_FAST and OPT_SLOW affect.  For best results, use OPT="-O2", and link
+with "-static".  Nearly the same results can be had with much better
+compile times with OPT_FAST="-O1 -fstrict-aliasing".
+
+Unfortunately, using the optimizer with SystemC files can result in
+compiles taking several minutes.  (The SystemC libraries have many little
+inlined functions that drive the compiler nuts.)
 
 For best results, use GCC 3.3 or newer.  GCC 3.2 and earlier have
 optimization bugs around pointer aliasing detection, which can result in 2x
diff --git a/src/Makefile_obj.in b/src/Makefile_obj.in
index 200c4a0fc..28a98c2c5 100644
--- a/src/Makefile_obj.in
+++ b/src/Makefile_obj.in
@@ -118,6 +118,7 @@ RAW_OBJS = \
 	V3Dead.o \
 	V3Delayed.o \
 	V3Depth.o \
+	V3DepthBlock.o \
 	V3Descope.o \
 	V3EmitC.o \
 	V3EmitCSyms.o \
diff --git a/src/V3Depth.cpp b/src/V3Depth.cpp
index 749a43459..3a9c884c3 100644
--- a/src/V3Depth.cpp
+++ b/src/V3Depth.cpp
@@ -40,7 +40,6 @@
 #include "V3Ast.h"
 
 //######################################################################
-// Depth state, as a visitor of each AstNode
 
 class DepthVisitor : public AstNVisitor {
 private:
@@ -55,11 +54,6 @@ private:
 
     //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);
@@ -114,13 +108,15 @@ private:
     virtual void visit(AstNodeTermop* nodep, AstNUser*) {
     }
     virtual void visit(AstNodeMath* nodep, AstNUser*) {
-	m_depth++;
+	// We have some operator defines that use 2 parens, so += 2.
+	m_depth += 2;
 	if (m_depth>m_maxdepth) m_maxdepth=m_depth;
 	nodep->iterateChildren(*this); 
-	m_depth--;
+	m_depth -= 2;
 
-	if ((m_maxdepth-m_depth) > MAX_EXPR_DEPTH
-	    && m_stmtp
+	if (m_stmtp
+	    && (v3Global.opt.compLimitParens() >= 1)	// Else compiler doesn't need it
+	    && (m_maxdepth-m_depth) > v3Global.opt.compLimitParens()
 	    && !nodep->backp()->castNodeStmt()  // Not much point if we're about to use it
 	    ) {
 	    m_maxdepth = m_depth;
@@ -173,14 +169,10 @@ public:
     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);
 }
diff --git a/src/V3DepthBlock.cpp b/src/V3DepthBlock.cpp
new file mode 100644
index 000000000..9d95b7ba7
--- /dev/null
+++ b/src/V3DepthBlock.cpp
@@ -0,0 +1,139 @@
+// $Id$
+//*************************************************************************
+// DESCRIPTION: Verilator: Prevent very deep expressions
+//
+// Code available from: http://www.veripool.com/verilator
+//
+// AUTHORS: Wilson Snyder with Paul Wasson, Duane Gabli
+//
+//*************************************************************************
+//
+// Copyright 2003-2007 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.
+//
+//*************************************************************************
+// V3DepthBlock's Transformations:
+//		
+// Each module:
+//	For each deep block, create cfunc including that block.
+//
+//*************************************************************************
+
+#include "config_build.h"
+#include "verilatedos.h"
+#include <stdio.h>
+#include <stdarg.h>
+#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
+    AstModule*		m_modp;		// Current module
+    AstCFunc*		m_funcp;	// Current function
+    int			m_depth;	// How deep in an expression
+    int			m_deepNum;	// How many functions made
+
+    //int debug() { return 9; }
+
+    // METHODS
+    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(AstModule* nodep, AstNUser*) {
+	UINFO(4," MOD   "<<nodep<<endl);
+	m_modp = nodep;
+	m_deepNum = 0;
+	nodep->iterateChildren(*this);
+    }
+    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(AstNode* 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);
+}
diff --git a/src/V3DepthBlock.h b/src/V3DepthBlock.h
new file mode 100644
index 000000000..7e441a9ff
--- /dev/null
+++ b/src/V3DepthBlock.h
@@ -0,0 +1,36 @@
+// $Id$ //-*- C++ -*-
+//*************************************************************************
+// DESCRIPTION: Verilator: Prevent very deep expressions
+//
+// 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.
+//
+//*************************************************************************
+
+#ifndef _V3DEPTHBLOCK_H_
+#define _V3DEPTHBLOCK_H_ 1
+#include "config_build.h"
+#include "verilatedos.h"
+#include "V3Error.h"
+#include "V3Ast.h"
+
+//============================================================================
+
+class V3DepthBlock {
+public:
+    static void depthBlockAll(AstNetlist* nodep);
+};
+
+#endif // Guard
diff --git a/src/V3Options.cpp b/src/V3Options.cpp
index 2f2cda186..13b3d9d98 100644
--- a/src/V3Options.cpp
+++ b/src/V3Options.cpp
@@ -454,18 +454,20 @@ void V3Options::parseOptsList(FileLine* fl, int argc, char** argv) {
 		    V3Error::pretendError(code, true);
 		}
 	    }
-	    else if ( !strcmp (sw, "-x-assign") && (i+1)<argc) {
-		shift;
-		if (!strcmp (argv[i], "0")) { m_xAssign="0"; }
-		else if (!strcmp (argv[i], "1")) { m_xAssign="1"; }
-		else if (!strcmp (argv[i], "unique")) { m_xAssign="unique"; }
-		else {
-		    fl->v3fatal("Unknown setting for -x-assign: "<<sw);
-		}
-	    }
 	    else if ( !strcmp (sw, "-bin") && (i+1)<argc ) {
 		shift; m_bin = argv[i];
 	    }
+	    else if ( !strcmp (sw, "-compiler") && (i+1)<argc) {
+		shift;
+		if (!strcmp (argv[i], "gcc")) {
+		    m_compLimitParens = 0;
+		} else if (!strcmp (argv[i], "msvc")) {
+		    m_compLimitParens = 80;   // 128, but allow some room
+		    m_compLimitBlocks = 80;   // 128, but allow some room
+		} else {
+		    fl->v3fatal("Unknown setting for --compiler: "<<argv[i]);
+		}
+	    }
 	    else if ( !strcmp (sw, "-f") && (i+1)<argc ) {
 		shift;
 		parseOptsFile(fl, argv[i]);
@@ -480,6 +482,15 @@ void V3Options::parseOptsList(FileLine* fl, int argc, char** argv) {
 		shift; m_prefix = argv[i];
 		if (m_modPrefix=="") m_modPrefix = m_prefix;
 	    }
+	    else if ( !strcmp (sw, "-x-assign") && (i+1)<argc) {
+		shift;
+		if (!strcmp (argv[i], "0")) { m_xAssign="0"; }
+		else if (!strcmp (argv[i], "1")) { m_xAssign="1"; }
+		else if (!strcmp (argv[i], "unique")) { m_xAssign="unique"; }
+		else {
+		    fl->v3fatal("Unknown setting for --x-assign: "<<argv[i]);
+		}
+	    }
 	    else if ( !strcmp (sw, "-y")) {
 		shift; addIncDir (string (argv[i]));
 	    }
@@ -599,6 +610,9 @@ V3Options::V3Options() {
     m_unrollCount = 64;
     m_unrollStmts = 20;
 
+    m_compLimitParens = 0;
+    m_compLimitBlocks = 0;
+
     m_makeDir = "obj_dir";
     m_bin = "";
     m_flags = "";
diff --git a/src/V3Options.h b/src/V3Options.h
index b3acb1fac..91029c2f8 100644
--- a/src/V3Options.h
+++ b/src/V3Options.h
@@ -77,6 +77,9 @@ class V3Options {
     int		m_unrollCount;	// main switch: --unroll-count
     int		m_unrollStmts;	// main switch: --unroll-stmts
 
+    int		m_compLimitBlocks;	// compiler selection options
+    int		m_compLimitParens;	// compiler selection options
+
     string	m_bin;		// main switch: --bin {binary}
     string	m_flags;	// main switch: -f {name}
     string	m_top;		// main switch: Top .v file name
@@ -162,6 +165,9 @@ class V3Options {
     int	   unrollCount() const { return m_unrollCount; }
     int	   unrollStmts() const { return m_unrollStmts; }
 
+    int    compLimitBlocks() const { return m_compLimitBlocks; }
+    int    compLimitParens() const { return m_compLimitParens; }
+
     string makeDir() const { return m_makeDir; }
     string prefix() const { return m_prefix; }
     string modPrefix() const { return m_modPrefix; }
@@ -169,6 +175,7 @@ class V3Options {
     const V3StringSet& cppFiles() const { return m_cppFiles; }
     const V3StringSet& libraryFiles() const { return m_libraryFiles; }
 
+
     // ACCESSORS (optimization options)
     bool oAcycSimp() const { return m_oAcycSimp; }
     bool oCase() const { return m_oCase; }
diff --git a/src/Verilator.cpp b/src/Verilator.cpp
index fddcc97d5..1a8387990 100644
--- a/src/Verilator.cpp
+++ b/src/Verilator.cpp
@@ -41,6 +41,7 @@
 #include "V3Dead.h"
 #include "V3Delayed.h"
 #include "V3Depth.h"
+#include "V3DepthBlock.h"
 #include "V3Descope.h"
 #include "V3EmitC.h"
 #include "V3EmitMk.h"
@@ -379,6 +380,12 @@ void process () {
 
     //--MODULE OPTIMIZATIONS--------------
 
+    // Split deep blocks to appease MSVC++.  Must be before Localize.
+    if (v3Global.opt.compLimitBlocks()) {
+	V3DepthBlock::depthBlockAll(v3Global.rootp());
+	v3Global.rootp()->dumpTreeFile(v3Global.debugFilename("deepblock.tree"));
+    }
+
     // Move BLOCKTEMPS from class to local variables
     if (v3Global.opt.oLocalize()) {
 	V3Localize::localizeAll(v3Global.rootp());
diff --git a/test_regress/driver.pl b/test_regress/driver.pl
index 8a5dd7149..2a5aa2222 100755
--- a/test_regress/driver.pl
+++ b/test_regress/driver.pl
@@ -205,6 +205,7 @@ sub new {
 	# Verilator
 	'v3' => 0,
 	verilator_flags => [split(/\s+/,"-cc")],
+	verilator_flags2 => [],
 	verilator_make_gcc => 1,
 	verilated_debug => $Opt_Verilated_Debug,
 	stdout_filename => undef,	# Redirect stdout
@@ -338,6 +339,7 @@ sub compile {
 	my @v3args = ("perl","../bin/verilator",
 		      "--prefix ".$self->{VM_PREFIX},
 		      @{$param{verilator_flags}},
+		      @{$param{verilator_flags2}},
 		      @{$param{v_flags}},
 		      @{$param{v_flags2}},
 		      $param{top_filename},
diff --git a/test_regress/t/t_case_deep.pl b/test_regress/t/t_case_deep.pl
new file mode 100755
index 000000000..c28ca5f05
--- /dev/null
+++ b/test_regress/t/t_case_deep.pl
@@ -0,0 +1,19 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("./driver.pl", @ARGV, $0); die; }
+# $Id$
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003 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.
+
+compile (
+	 verilator_flags2 => ["--compiler msvc"],  # We have deep expressions we want to test
+	 );
+
+execute (
+	 check_finished=>1,
+     );
+
+ok(1);
+1;
diff --git a/test_regress/t/t_case_deep.v b/test_regress/t/t_case_deep.v
new file mode 100644
index 000000000..8d1e25c53
--- /dev/null
+++ b/test_regress/t/t_case_deep.v
@@ -0,0 +1,342 @@
+// $Id$
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed into the Public Domain, for any use,
+// without warranty, 2007 by Wilson Snyder.
+
+module t (/*AUTOARG*/
+   // Inputs
+   clk
+   );
+   input clk;
+
+   integer 	cyc=0;
+   reg [63:0] 	crc;
+   reg [63:0] 	sum;
+
+   // Take CRC data and apply to testblock inputs
+   wire [33:0]  in = crc[33:0];
+
+   /*AUTOWIRE*/
+   // Beginning of automatic wires (for undeclared instantiated-module outputs)
+   wire [31:0]		code;			// From test of Test.v
+   wire [4:0]		len;			// From test of Test.v
+   wire			next;			// From test of Test.v
+   // End of automatics
+
+   Test test (/*AUTOINST*/
+	      // Outputs
+	      .next			(next),
+	      .code			(code[31:0]),
+	      .len			(len[4:0]),
+	      // Inputs
+	      .clk			(clk),
+	      .in			(in[33:0]));
+
+   // Aggregate outputs into a single result vector
+   wire [63:0] result = {26'h0, next, len, code};
+
+   // What checksum will we end up with
+`define EXPECTED_SUM 64'h5537fa30d49bf865
+
+   // Test loop
+   always @ (posedge clk) begin
+`ifdef TEST_VERBOSE
+      $write("[%0t] cyc==%0d crc=%x result=%x\n",$time, cyc, crc, result);
+`endif
+      cyc <= cyc + 1;
+      crc <= {crc[62:0], crc[63]^crc[2]^crc[0]};
+      sum <= result ^ {sum[62:0],sum[63]^sum[2]^sum[0]};
+      if (cyc==0) begin
+	 // Setup
+	 crc <= 64'h5aef0c8d_d70a4497;
+      end
+      else if (cyc<10) begin
+	 sum <= 64'h0;
+      end
+      else if (cyc<90) begin
+      end
+      else if (cyc==99) begin
+	 $write("[%0t] cyc==%0d crc=%x sum=%x\n",$time, cyc, crc, sum);
+	 if (crc !== 64'hc77bb9b3784ea091) $stop;
+	 if (sum !== `EXPECTED_SUM) $stop;
+	 $write("*-* All Finished *-*\n");
+	 $finish;
+      end
+   end
+
+endmodule
+
+module Test (/*AUTOARG*/
+   // Outputs
+   next, code, len,
+   // Inputs
+   clk, in
+   );
+
+   input clk;
+   input  [33:0] in;   
+   output 	 next;
+   output [31:0] code;
+   output [4:0]	 len;
+
+   /*AUTOREG*/
+   // Beginning of automatic regs (for this module's undeclared outputs)
+   reg [31:0]		code;
+   reg [4:0]		len;
+   reg			next;
+   // End of automatics
+
+/*
+#!/usr/bin/perl -w
+srand(5);
+my @used;
+pat:
+  for (my $pat=0; 1; ) {
+    last if $pat > 196;
+    my $len = int($pat / (6 + $pat/50)) + 4;  $len=20 if $len>20;
+    my ($try, $val, $mask);
+  try:
+    for ($try=0; ; $try++) {
+	next pat if $try>50;
+	$val = 0;
+	for (my $bit=23; $bit>(23-$len); $bit--) {
+	    my $b = int(rand()*2);
+	    $val |= (1<<$bit) if $b;
+	}
+	$mask = (1<<(23-$len+1))-1;
+	for (my $testval = $val; $testval <= ($val + $mask); $testval ++) {
+	    next try if $used[$testval];
+	}
+	last;
+    }
+    my $bits = "";
+    my $val2 = 0;
+    for (my $bit=23; $bit>(23-$len); $bit--) {
+	my $b = ($val & (1<<$bit));
+	$bits .= $b?'1':'0';
+    }
+    for (my $testval = $val; $testval <= ($val + $mask); $testval++) {
+	$used[$testval]= 1; #printf "U%08x\n", $testval;
+    }
+    if ($try<90) {
+	printf +("     24'b%s: {next, len, code} = {in[%02d], 5'd%02d, 32'd%03d};\n"
+		 ,$bits.("?"x(24-$len)), 31-$len, $len, $pat);
+	$pat++;
+    }
+}
+*/
+
+   always @* begin
+      next = 1'b0;
+      code = 32'd0;
+      len  = 5'b11111;
+      casez (in[31:8])
+	24'b1010????????????????????: {next, len, code} = {in[27], 5'd04, 32'd000};
+	24'b1100????????????????????: {next, len, code} = {in[27], 5'd04, 32'd001};
+	24'b0110????????????????????: {next, len, code} = {in[27], 5'd04, 32'd002};
+	24'b1001????????????????????: {next, len, code} = {in[27], 5'd04, 32'd003};
+	24'b1101????????????????????: {next, len, code} = {in[27], 5'd04, 32'd004};
+	24'b0011????????????????????: {next, len, code} = {in[27], 5'd04, 32'd005};
+	24'b0001????????????????????: {next, len, code} = {in[27], 5'd04, 32'd006};
+	24'b10001???????????????????: {next, len, code} = {in[26], 5'd05, 32'd007};
+	24'b01110???????????????????: {next, len, code} = {in[26], 5'd05, 32'd008};
+	24'b01000???????????????????: {next, len, code} = {in[26], 5'd05, 32'd009};
+	24'b00001???????????????????: {next, len, code} = {in[26], 5'd05, 32'd010};
+	24'b11100???????????????????: {next, len, code} = {in[26], 5'd05, 32'd011};
+	24'b01011???????????????????: {next, len, code} = {in[26], 5'd05, 32'd012};
+	24'b100001??????????????????: {next, len, code} = {in[25], 5'd06, 32'd013};
+	24'b111110??????????????????: {next, len, code} = {in[25], 5'd06, 32'd014};
+	24'b010010??????????????????: {next, len, code} = {in[25], 5'd06, 32'd015};
+	24'b001011??????????????????: {next, len, code} = {in[25], 5'd06, 32'd016};
+	24'b101110??????????????????: {next, len, code} = {in[25], 5'd06, 32'd017};
+	24'b111011??????????????????: {next, len, code} = {in[25], 5'd06, 32'd018};
+	24'b0111101?????????????????: {next, len, code} = {in[24], 5'd07, 32'd020};
+	24'b0010100?????????????????: {next, len, code} = {in[24], 5'd07, 32'd021};
+	24'b0111111?????????????????: {next, len, code} = {in[24], 5'd07, 32'd022};
+	24'b1011010?????????????????: {next, len, code} = {in[24], 5'd07, 32'd023};
+	24'b1000000?????????????????: {next, len, code} = {in[24], 5'd07, 32'd024};
+	24'b1011111?????????????????: {next, len, code} = {in[24], 5'd07, 32'd025};
+	24'b1110100?????????????????: {next, len, code} = {in[24], 5'd07, 32'd026};
+	24'b01111100????????????????: {next, len, code} = {in[23], 5'd08, 32'd027};
+	24'b00000110????????????????: {next, len, code} = {in[23], 5'd08, 32'd028};
+	24'b00000101????????????????: {next, len, code} = {in[23], 5'd08, 32'd029};
+	24'b01001100????????????????: {next, len, code} = {in[23], 5'd08, 32'd030};
+	24'b10110110????????????????: {next, len, code} = {in[23], 5'd08, 32'd031};
+	24'b00100110????????????????: {next, len, code} = {in[23], 5'd08, 32'd032};
+	24'b11110010????????????????: {next, len, code} = {in[23], 5'd08, 32'd033};
+	24'b010011101???????????????: {next, len, code} = {in[22], 5'd09, 32'd034};
+	24'b001000000???????????????: {next, len, code} = {in[22], 5'd09, 32'd035};
+	24'b010101111???????????????: {next, len, code} = {in[22], 5'd09, 32'd036};
+	24'b010101010???????????????: {next, len, code} = {in[22], 5'd09, 32'd037};
+	24'b010011011???????????????: {next, len, code} = {in[22], 5'd09, 32'd038};
+	24'b010100011???????????????: {next, len, code} = {in[22], 5'd09, 32'd039};
+	24'b010101000???????????????: {next, len, code} = {in[22], 5'd09, 32'd040};
+	24'b1111010101??????????????: {next, len, code} = {in[21], 5'd10, 32'd041};
+	24'b0010001000??????????????: {next, len, code} = {in[21], 5'd10, 32'd042};
+	24'b0101001101??????????????: {next, len, code} = {in[21], 5'd10, 32'd043};
+	24'b0010010100??????????????: {next, len, code} = {in[21], 5'd10, 32'd044};
+	24'b1011001110??????????????: {next, len, code} = {in[21], 5'd10, 32'd045};
+	24'b1111000011??????????????: {next, len, code} = {in[21], 5'd10, 32'd046};
+	24'b0101000000??????????????: {next, len, code} = {in[21], 5'd10, 32'd047};
+	24'b1111110000??????????????: {next, len, code} = {in[21], 5'd10, 32'd048};
+	24'b10110111010?????????????: {next, len, code} = {in[20], 5'd11, 32'd049};
+	24'b11110000011?????????????: {next, len, code} = {in[20], 5'd11, 32'd050};
+	24'b01001111011?????????????: {next, len, code} = {in[20], 5'd11, 32'd051};
+	24'b00101011011?????????????: {next, len, code} = {in[20], 5'd11, 32'd052};
+	24'b01010010100?????????????: {next, len, code} = {in[20], 5'd11, 32'd053};
+	24'b11110111100?????????????: {next, len, code} = {in[20], 5'd11, 32'd054};
+	24'b00100111001?????????????: {next, len, code} = {in[20], 5'd11, 32'd055};
+	24'b10110001010?????????????: {next, len, code} = {in[20], 5'd11, 32'd056};
+	24'b10000010000?????????????: {next, len, code} = {in[20], 5'd11, 32'd057};
+	24'b111111101100????????????: {next, len, code} = {in[19], 5'd12, 32'd058};
+	24'b100000111110????????????: {next, len, code} = {in[19], 5'd12, 32'd059};
+	24'b100000110010????????????: {next, len, code} = {in[19], 5'd12, 32'd060};
+	24'b100000111001????????????: {next, len, code} = {in[19], 5'd12, 32'd061};
+	24'b010100101111????????????: {next, len, code} = {in[19], 5'd12, 32'd062};
+	24'b001000001100????????????: {next, len, code} = {in[19], 5'd12, 32'd063};
+	24'b000001111111????????????: {next, len, code} = {in[19], 5'd12, 32'd064};
+	24'b011111010100????????????: {next, len, code} = {in[19], 5'd12, 32'd065};
+	24'b1110101111101???????????: {next, len, code} = {in[18], 5'd13, 32'd066};
+	24'b0100110101110???????????: {next, len, code} = {in[18], 5'd13, 32'd067};
+	24'b1111111011011???????????: {next, len, code} = {in[18], 5'd13, 32'd068};
+	24'b0101011011001???????????: {next, len, code} = {in[18], 5'd13, 32'd069};
+	24'b0010000101100???????????: {next, len, code} = {in[18], 5'd13, 32'd070};
+	24'b1111111101101???????????: {next, len, code} = {in[18], 5'd13, 32'd071};
+	24'b1011110010110???????????: {next, len, code} = {in[18], 5'd13, 32'd072};
+	24'b0101010111010???????????: {next, len, code} = {in[18], 5'd13, 32'd073};
+	24'b1111011010010???????????: {next, len, code} = {in[18], 5'd13, 32'd074};
+	24'b01010100100011??????????: {next, len, code} = {in[17], 5'd14, 32'd075};
+	24'b10110000110010??????????: {next, len, code} = {in[17], 5'd14, 32'd076};
+	24'b10111101001111??????????: {next, len, code} = {in[17], 5'd14, 32'd077};
+	24'b10110000010101??????????: {next, len, code} = {in[17], 5'd14, 32'd078};
+	24'b00101011001111??????????: {next, len, code} = {in[17], 5'd14, 32'd079};
+	24'b00100000101100??????????: {next, len, code} = {in[17], 5'd14, 32'd080};
+	24'b11111110010111??????????: {next, len, code} = {in[17], 5'd14, 32'd081};
+	24'b10110010100000??????????: {next, len, code} = {in[17], 5'd14, 32'd082};
+	24'b11101011101000??????????: {next, len, code} = {in[17], 5'd14, 32'd083};
+	24'b01010000011111??????????: {next, len, code} = {in[17], 5'd14, 32'd084};
+	24'b101111011001011?????????: {next, len, code} = {in[16], 5'd15, 32'd085};
+	24'b101111010001100?????????: {next, len, code} = {in[16], 5'd15, 32'd086};
+	24'b100000111100111?????????: {next, len, code} = {in[16], 5'd15, 32'd087};
+	24'b001010101011000?????????: {next, len, code} = {in[16], 5'd15, 32'd088};
+	24'b111111100100001?????????: {next, len, code} = {in[16], 5'd15, 32'd089};
+	24'b001001011000010?????????: {next, len, code} = {in[16], 5'd15, 32'd090};
+	24'b011110011001011?????????: {next, len, code} = {in[16], 5'd15, 32'd091};
+	24'b111111111111010?????????: {next, len, code} = {in[16], 5'd15, 32'd092};
+	24'b101111001010011?????????: {next, len, code} = {in[16], 5'd15, 32'd093};
+	24'b100000110000111?????????: {next, len, code} = {in[16], 5'd15, 32'd094};
+	24'b0010010000000101????????: {next, len, code} = {in[15], 5'd16, 32'd095};
+	24'b0010010010101001????????: {next, len, code} = {in[15], 5'd16, 32'd096};
+	24'b1111011010110010????????: {next, len, code} = {in[15], 5'd16, 32'd097};
+	24'b0010010001100100????????: {next, len, code} = {in[15], 5'd16, 32'd098};
+	24'b0101011101110100????????: {next, len, code} = {in[15], 5'd16, 32'd099};
+	24'b0101011010001111????????: {next, len, code} = {in[15], 5'd16, 32'd100};
+	24'b0010000110011111????????: {next, len, code} = {in[15], 5'd16, 32'd101};
+	24'b0101010010000101????????: {next, len, code} = {in[15], 5'd16, 32'd102};
+	24'b1110101011000000????????: {next, len, code} = {in[15], 5'd16, 32'd103};
+	24'b1111000000110010????????: {next, len, code} = {in[15], 5'd16, 32'd104};
+	24'b0111100010001101????????: {next, len, code} = {in[15], 5'd16, 32'd105};
+	24'b00100010110001100???????: {next, len, code} = {in[14], 5'd17, 32'd106};
+	24'b00100010101101010???????: {next, len, code} = {in[14], 5'd17, 32'd107};
+	24'b11111110111100000???????: {next, len, code} = {in[14], 5'd17, 32'd108};
+	24'b00100000111010000???????: {next, len, code} = {in[14], 5'd17, 32'd109};
+	24'b00100111011101001???????: {next, len, code} = {in[14], 5'd17, 32'd110};
+	24'b11111110111000011???????: {next, len, code} = {in[14], 5'd17, 32'd111};
+	24'b11110001101000100???????: {next, len, code} = {in[14], 5'd17, 32'd112};
+	24'b11101011101011101???????: {next, len, code} = {in[14], 5'd17, 32'd113};
+	24'b01010000100101011???????: {next, len, code} = {in[14], 5'd17, 32'd114};
+	24'b00100100110011001???????: {next, len, code} = {in[14], 5'd17, 32'd115};
+	24'b01001110010101000???????: {next, len, code} = {in[14], 5'd17, 32'd116};
+	24'b010011110101001000??????: {next, len, code} = {in[13], 5'd18, 32'd117};
+	24'b111010101110010010??????: {next, len, code} = {in[13], 5'd18, 32'd118};
+	24'b001001001001111000??????: {next, len, code} = {in[13], 5'd18, 32'd119};
+	24'b101111000110111101??????: {next, len, code} = {in[13], 5'd18, 32'd120};
+	24'b101101111010101001??????: {next, len, code} = {in[13], 5'd18, 32'd121};
+	24'b111101110010111110??????: {next, len, code} = {in[13], 5'd18, 32'd122};
+	24'b010100100011010000??????: {next, len, code} = {in[13], 5'd18, 32'd123};
+	24'b001001001111011001??????: {next, len, code} = {in[13], 5'd18, 32'd124};
+	24'b010100110010001001??????: {next, len, code} = {in[13], 5'd18, 32'd125};
+	24'b111010110000111000??????: {next, len, code} = {in[13], 5'd18, 32'd126};
+	24'b111010110011000101??????: {next, len, code} = {in[13], 5'd18, 32'd127};
+	24'b010100001000111001??????: {next, len, code} = {in[13], 5'd18, 32'd128};
+	24'b1000001011000110100?????: {next, len, code} = {in[12], 5'd19, 32'd129};
+	24'b0010010111001110110?????: {next, len, code} = {in[12], 5'd19, 32'd130};
+	24'b0101011001000001101?????: {next, len, code} = {in[12], 5'd19, 32'd131};
+	24'b0101000010010101011?????: {next, len, code} = {in[12], 5'd19, 32'd132};
+	24'b1111011111101001101?????: {next, len, code} = {in[12], 5'd19, 32'd133};
+	24'b1011001000101010110?????: {next, len, code} = {in[12], 5'd19, 32'd134};
+	24'b1011000001000100001?????: {next, len, code} = {in[12], 5'd19, 32'd135};
+	24'b1110101100010011001?????: {next, len, code} = {in[12], 5'd19, 32'd136};
+	24'b0010010111010111110?????: {next, len, code} = {in[12], 5'd19, 32'd137};
+	24'b0010010001100111100?????: {next, len, code} = {in[12], 5'd19, 32'd138};
+	24'b1011001011100000101?????: {next, len, code} = {in[12], 5'd19, 32'd139};
+	24'b1011000100010100101?????: {next, len, code} = {in[12], 5'd19, 32'd140};
+	24'b1111111001000111011?????: {next, len, code} = {in[12], 5'd19, 32'd141};
+	24'b00100010111101101101????: {next, len, code} = {in[11], 5'd20, 32'd142};
+	24'b10000010101010101101????: {next, len, code} = {in[11], 5'd20, 32'd143};
+	24'b10110010100101001101????: {next, len, code} = {in[11], 5'd20, 32'd144};
+	24'b01010110111100010000????: {next, len, code} = {in[11], 5'd20, 32'd145};
+	24'b10110111110011001001????: {next, len, code} = {in[11], 5'd20, 32'd146};
+	24'b11111101101100100101????: {next, len, code} = {in[11], 5'd20, 32'd147};
+	24'b10110000010100100001????: {next, len, code} = {in[11], 5'd20, 32'd148};
+	24'b10110010011010110110????: {next, len, code} = {in[11], 5'd20, 32'd149};
+	24'b01111001010000011000????: {next, len, code} = {in[11], 5'd20, 32'd150};
+	24'b11110110001011011011????: {next, len, code} = {in[11], 5'd20, 32'd151};
+	24'b01010000100100001011????: {next, len, code} = {in[11], 5'd20, 32'd152};
+	24'b10110001100101110111????: {next, len, code} = {in[11], 5'd20, 32'd153};
+	24'b10111100110111101000????: {next, len, code} = {in[11], 5'd20, 32'd154};
+	24'b01010001010111010000????: {next, len, code} = {in[11], 5'd20, 32'd155};
+	24'b01010100111110001110????: {next, len, code} = {in[11], 5'd20, 32'd156};
+	24'b11111110011001100111????: {next, len, code} = {in[11], 5'd20, 32'd157};
+	24'b11110111111101010001????: {next, len, code} = {in[11], 5'd20, 32'd158};
+	24'b10110000010111100000????: {next, len, code} = {in[11], 5'd20, 32'd159};
+	24'b01001111100001000101????: {next, len, code} = {in[11], 5'd20, 32'd160};
+	24'b01010010000111010110????: {next, len, code} = {in[11], 5'd20, 32'd161};
+	24'b11101010101011101111????: {next, len, code} = {in[11], 5'd20, 32'd162};
+	24'b11111110010011100011????: {next, len, code} = {in[11], 5'd20, 32'd163};
+	24'b01010111001111101111????: {next, len, code} = {in[11], 5'd20, 32'd164};
+	24'b10110001111111111101????: {next, len, code} = {in[11], 5'd20, 32'd165};
+	24'b10110001001100110000????: {next, len, code} = {in[11], 5'd20, 32'd166};
+	24'b11110100011000111101????: {next, len, code} = {in[11], 5'd20, 32'd167};
+	24'b00101011101110100011????: {next, len, code} = {in[11], 5'd20, 32'd168};
+	24'b01010000011011111110????: {next, len, code} = {in[11], 5'd20, 32'd169};
+	24'b00000111000010000010????: {next, len, code} = {in[11], 5'd20, 32'd170};
+	24'b00101010000011001000????: {next, len, code} = {in[11], 5'd20, 32'd171};
+	24'b01001110010100101110????: {next, len, code} = {in[11], 5'd20, 32'd172};
+	24'b11110000000010000000????: {next, len, code} = {in[11], 5'd20, 32'd173};
+	24'b01001101011001111001????: {next, len, code} = {in[11], 5'd20, 32'd174};
+	24'b11110111000111010101????: {next, len, code} = {in[11], 5'd20, 32'd175};
+	24'b01111001101001110110????: {next, len, code} = {in[11], 5'd20, 32'd176};
+	24'b11110000101011101111????: {next, len, code} = {in[11], 5'd20, 32'd177};
+	24'b00100100100110101010????: {next, len, code} = {in[11], 5'd20, 32'd178};
+	24'b11110001011011000011????: {next, len, code} = {in[11], 5'd20, 32'd179};
+	24'b01010111001000110011????: {next, len, code} = {in[11], 5'd20, 32'd180};
+	24'b01111000000100010101????: {next, len, code} = {in[11], 5'd20, 32'd181};
+	24'b00100101101011001101????: {next, len, code} = {in[11], 5'd20, 32'd182};
+	24'b10110010110000111001????: {next, len, code} = {in[11], 5'd20, 32'd183};
+	24'b10110000101010000011????: {next, len, code} = {in[11], 5'd20, 32'd184};
+	24'b00100100111110001101????: {next, len, code} = {in[11], 5'd20, 32'd185};
+	24'b01111001101001101011????: {next, len, code} = {in[11], 5'd20, 32'd186};
+	24'b01010001000000010001????: {next, len, code} = {in[11], 5'd20, 32'd187};
+	24'b11110101111111101110????: {next, len, code} = {in[11], 5'd20, 32'd188};
+	24'b10000010111110110011????: {next, len, code} = {in[11], 5'd20, 32'd189};
+	24'b00000100011110100111????: {next, len, code} = {in[11], 5'd20, 32'd190};
+	24'b11111101001111101100????: {next, len, code} = {in[11], 5'd20, 32'd191};
+	24'b00101011100011110000????: {next, len, code} = {in[11], 5'd20, 32'd192};
+	24'b00100100111001011001????: {next, len, code} = {in[11], 5'd20, 32'd193};
+	24'b10000010101000000100????: {next, len, code} = {in[11], 5'd20, 32'd194};
+	24'b11110001001000111100????: {next, len, code} = {in[11], 5'd20, 32'd195};
+	24'b10111100011010011001????: {next, len, code} = {in[11], 5'd20, 32'd196};
+	24'b000000??????????????????: begin
+	   casez (in[33:32])
+	     2'b1?:   {next, len, code} = {1'b0, 5'd18, 32'd197};
+	     2'b01:   {next, len, code} = {1'b0, 5'd19, 32'd198};
+	     2'b00:   {next, len, code} = {1'b0, 5'd19, 32'd199};
+	     default: ;
+	   endcase
+	end
+	default: ;
+      endcase
+   end
+endmodule
diff --git a/test_regress/t/t_func_crc.pl b/test_regress/t/t_func_crc.pl
index 7bfdbe852..c28ca5f05 100755
--- a/test_regress/t/t_func_crc.pl
+++ b/test_regress/t/t_func_crc.pl
@@ -8,6 +8,7 @@ if (!$::Driver) { use FindBin; exec("./driver.pl", @ARGV, $0); die; }
 # General Public License or the Perl Artistic License.
 
 compile (
+	 verilator_flags2 => ["--compiler msvc"],  # We have deep expressions we want to test
 	 );
 
 execute (
diff --git a/test_regress/t/t_if_deep.pl b/test_regress/t/t_if_deep.pl
new file mode 100755
index 000000000..c28ca5f05
--- /dev/null
+++ b/test_regress/t/t_if_deep.pl
@@ -0,0 +1,19 @@
+#!/usr/bin/perl
+if (!$::Driver) { use FindBin; exec("./driver.pl", @ARGV, $0); die; }
+# $Id$
+# DESCRIPTION: Verilator: Verilog Test driver/expect definition
+#
+# Copyright 2003 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.
+
+compile (
+	 verilator_flags2 => ["--compiler msvc"],  # We have deep expressions we want to test
+	 );
+
+execute (
+	 check_finished=>1,
+     );
+
+ok(1);
+1;
diff --git a/test_regress/t/t_if_deep.v b/test_regress/t/t_if_deep.v
new file mode 100644
index 000000000..e55aae8a6
--- /dev/null
+++ b/test_regress/t/t_if_deep.v
@@ -0,0 +1,141 @@
+// $Id$
+// DESCRIPTION: Verilator: Verilog Test module
+//
+// This file ONLY is placed into the Public Domain, for any use,
+// without warranty, 2007 by Wilson Snyder.
+
+module t (/*AUTOARG*/
+   // Inputs
+   clk
+   );
+   input clk;
+
+   integer 	cyc=0;
+   reg [63:0] 	crc;
+   reg [63:0] 	sum;
+
+   // Take CRC data and apply to testblock inputs
+   wire [31:0]  in = crc[31:0];
+
+   /*AUTOWIRE*/
+   // Beginning of automatic wires (for undeclared instantiated-module outputs)
+   wire [31:0]		out;			// From test of Test.v
+   // End of automatics
+
+   Test test (/*AUTOINST*/
+	      // Outputs
+	      .out			(out[31:0]),
+	      // Inputs
+	      .clk			(clk),
+	      .in			(in[31:0]));
+
+   // Aggregate outputs into a single result vector
+   wire [63:0] result = {32'h0, out};
+
+   // What checksum will we end up with
+`define EXPECTED_SUM 64'h966e272fd829e672
+
+   // Test loop
+   always @ (posedge clk) begin
+`ifdef TEST_VERBOSE
+      $write("[%0t] cyc==%0d crc=%x result=%x\n",$time, cyc, crc, result);
+`endif
+      cyc <= cyc + 1;
+      crc <= {crc[62:0], crc[63]^crc[2]^crc[0]};
+      sum <= result ^ {sum[62:0],sum[63]^sum[2]^sum[0]};
+      if (cyc==0) begin
+	 // Setup
+	 crc <= 64'h5aef0c8d_d70a4497;
+      end
+      else if (cyc<10) begin
+	 sum <= 64'h0;
+      end
+      else if (cyc<90) begin
+      end
+      else if (cyc==99) begin
+	 $write("[%0t] cyc==%0d crc=%x sum=%x\n",$time, cyc, crc, sum);
+	 if (crc !== 64'hc77bb9b3784ea091) $stop;
+	 if (sum !== `EXPECTED_SUM) $stop;
+	 $write("*-* All Finished *-*\n");
+	 $finish;
+      end
+   end
+
+endmodule
+
+module Test (/*AUTOARG*/
+   // Outputs
+   out,
+   // Inputs
+   clk, in
+   );
+
+   input clk;
+   input  [31:0] in;   
+   output [31:0] out;
+
+   /*AUTOREG*/
+   // Beginning of automatic regs (for this module's undeclared outputs)
+   reg [31:0]		out;
+   // End of automatics
+
+`ifdef verilator
+ `define dontOptimize $c1("1")
+`else
+ `define dontOptimize 1'b1
+`endif
+
+   always @(posedge clk) begin
+      out <= in;
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+      if (`dontOptimize) if (`dontOptimize) if (`dontOptimize) if (`dontOptimize)
+	if (in[0])
+	  out <= ~in;
+   end
+endmodule
diff --git a/test_regress/t/t_math_imm.pl b/test_regress/t/t_math_imm.pl
index 7bfdbe852..c28ca5f05 100755
--- a/test_regress/t/t_math_imm.pl
+++ b/test_regress/t/t_math_imm.pl
@@ -8,6 +8,7 @@ if (!$::Driver) { use FindBin; exec("./driver.pl", @ARGV, $0); die; }
 # General Public License or the Perl Artistic License.
 
 compile (
+	 verilator_flags2 => ["--compiler msvc"],  # We have deep expressions we want to test
 	 );
 
 execute (