From b6e8133a4df71bc4c751550e2b66651c2f33ad78 Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Sat, 19 May 2018 07:52:07 -0400
Subject: [PATCH] When tracing, use scalars on single bit arrays to appease
 vcddiff.

---
 Changes         |  2 ++
 src/V3EmitC.cpp | 11 ++++++++---
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/Changes b/Changes
index d4f9ad955..76461b227 100644
--- a/Changes
+++ b/Changes
@@ -6,6 +6,8 @@ The contributors that suggested a given feature are shown in []. Thanks!
 
 ****  Report interface ports connected to wrong interface, bug1294. [Todd Strader]
 
+****  When tracing, use scalars on single bit arrays to appease vcddiff.
+
 ****  Fix parsing "output signed" in V2K port list, msg2540. [James Jung]
 
 ****  Fix parsing error on bad missing #, bug1308. [Dan Kirkham]
diff --git a/src/V3EmitC.cpp b/src/V3EmitC.cpp
index e0586e991..2fe788869 100644
--- a/src/V3EmitC.cpp
+++ b/src/V3EmitC.cpp
@@ -2405,14 +2405,20 @@ class EmitCTrace : EmitCStmts {
 	string full = ((m_funcp->funcType() == AstCFuncType::TRACE_FULL
 			|| m_funcp->funcType() == AstCFuncType::TRACE_FULL_SUB)
 		       ? "full":"chg");
+        bool emitWidth = false;
 	if (nodep->dtypep()->basicp()->isDouble()) {
 	    puts("vcdp->"+full+"Double");
 	} else if (nodep->isWide() || emitTraceIsScBv(nodep) || emitTraceIsScBigUint(nodep)) {
 	    puts("vcdp->"+full+"Array");
+            emitWidth = true;
 	} else if (nodep->isQuad()) {
 	    puts("vcdp->"+full+"Quad ");
-	} else if (nodep->declp()->bitRange().ranged()) {
+            emitWidth = true;
+        } else if (nodep->declp()->bitRange().ranged()
+                   // 1 element smaller to use Bit dump
+                   && nodep->declp()->bitRange().elements() != 1) {
 	    puts("vcdp->"+full+"Bus  ");
+            emitWidth = true;
 	} else {
 	    puts("vcdp->"+full+"Bit  ");
 	}
@@ -2420,8 +2426,7 @@ class EmitCTrace : EmitCStmts {
 			    + ((arrayindex<0) ? 0 : (arrayindex*nodep->declp()->widthWords()))));
 	puts(",");
 	emitTraceValue(nodep, arrayindex);
-	if (!nodep->dtypep()->basicp()->isDouble()  // When float/double no longer have widths this can go
-	    && (nodep->declp()->bitRange().ranged() || emitTraceIsScBv(nodep) || emitTraceIsScBigUint(nodep))) {
+        if (emitWidth) {
 	    puts(","+cvtToStr(nodep->declp()->widthMin()));
 	}
 	puts(");\n");