Fix isolate_assignments when many signals per always.

git-svn-id: file://localhost/svn/verilator/trunk/verilator@877 77ca24e4-aefa-0310-84f0-b9a241c72d87

Changes

@@ -7,6 +7,8 @@ indicates the contributor was also the author of the fix; Thanks!
 
 ***  Add --trace-depth option for minimizing VCD file size. [Emerson Suguimoto]
 
+**** Fix isolate_assignments when many signals per always. [Mike Shinkarovsky]
+
 * Verilator 3.632 1/17/2007
 
 ***  Add /*verilator isolate_assignments*/ attribute.  [Mike Shinkarovsky]

bin/verilator

@@ -108,6 +108,7 @@ if ($Opt_Sp eq 'sp' || $Opt_Trace) {
 	$ENV{SYSTEMPERL} = $try if -d $try;
     }
     (defined $ENV{SYSTEMPERL}) or die "%Error: verilator: Need \$SYSTEMPERL in environment for --sp or --trace\nProbably System-Perl isn't installed, see http://www.veripool.com/systemperl.html\n";
+    (-d "$ENV{SYSTEMPERL}/src") or die "%Error: verilator: \$SYSTEMPERL environment var doesn't seem to point to System-Perl kit\n";
 }
 
 # Determine runtime flags
@@ -1082,7 +1083,7 @@ submodules will be named I<submodule>__DOT__I<subsignal> as C++ does not
 allow "." in signal names.  SystemPerl when tracing such signals will
 replace the __DOT__ with the period.
 
-=item /*verilator isolate_asignments*/
+=item /*verilator isolate_assignments*/
 
 Used after a signal declaration to indicate the assignments to this signal
 in any blocks should be isolated into new blocks.  When there is a large
@@ -1091,7 +1092,7 @@ this to the signal causing a false loop may clear up the problem.
 
 IE, with the following
 
-    reg splitme /* verilator isolate_asignments*/;
+    reg splitme /* verilator isolate_assignments*/;
     always @* begin
       if (....) begin
          splitme = ....;
@@ -1570,7 +1571,7 @@ clock_enable meta comment described above.
 
 The UNOPTFLAT warning may also occur where outputs from a block of logic
 are independent, but occur in the same always block.  To fix this, use the
-isolate_asignments meta comment described above.
+isolate_assignments meta comment described above.
 
 =item UNSIGNED
 

src/V3AstNodes.h

@@ -241,7 +241,7 @@ private:
     bool	m_funcLocal:1;	// Local variable for a function
     bool	m_funcReturn:1;	// Return variable for a function
     bool	m_attrClockEn:1;// User clock enable attribute
-    bool	m_attrIsolateAssign:1;// User isolate_asignments attribute
+    bool	m_attrIsolateAssign:1;// User isolate_assignments attribute
     bool	m_fileDescr:1;	// File descriptor
     bool	m_isConst:1;	// Table contains constant data
     bool	m_isStatic:1;	// Static variable

src/V3SplitAs.cpp

@@ -20,7 +20,7 @@
 //*************************************************************************
 // V3SplitAs's Transformations:
 //
-//	Search each ALWAYS for a VARREF lvalue with a /*isolate_asignments*/ attribute
+//	Search each ALWAYS for a VARREF lvalue with a /*isolate_assignments*/ attribute
 //	If found, color statements with both, assignment to that varref, or other assignments.
 //	Replicate the Always, and remove mis-colored duplicate code.
 //
@@ -166,12 +166,23 @@ private:
     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()) {
+	AstVarScope* lastSplitVscp = NULL;
+	while (!nodep->user()) {
+	    // Find any splittable variables
 	    SplitAsFindVisitor visitor (nodep);
 	    m_splitVscp = visitor.splitVscp();
+	    if (m_splitVscp && m_splitVscp == lastSplitVscp) {
+		// We did this last time!  Something's stuck!
+		nodep->v3fatalSrc("Infinite loop in isolate_assignments removal for: "<<m_splitVscp->prettyName())
+		m_splitVscp = NULL;
+	    }
+	    lastSplitVscp = m_splitVscp;
+	    // Now isolate the always
 	    if (m_splitVscp) {
 		splitAlways(nodep);
 		m_statSplits++;
+	    } else {
+		nodep->user(true);
 	    }
 	}
     }