From bd5d4c61c681eb6259991e41c2128dc971b7d7af Mon Sep 17 00:00:00 2001
From: Wilson Snyder <wsnyder@wsnyder.org>
Date: Wed, 1 Apr 2020 19:23:52 -0400
Subject: [PATCH] Suppress REALCVT for small whole real numbers.

---
 src/V3Number.h  | 9 +++++++++
 src/V3Width.cpp | 7 +++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/src/V3Number.h b/src/V3Number.h
index b565f2662..5c1645842 100644
--- a/src/V3Number.h
+++ b/src/V3Number.h
@@ -22,10 +22,19 @@
 
 #include "V3Error.h"
 
+#include <cmath>
+#include <limits>
 #include <vector>
 
 //============================================================================
 
+// Return if two numbers within Epsilon of each other
+inline bool v3EpsilonEqual(double a, double b) {
+    return fabs(a - b) <= (std::numeric_limits<double>::epsilon() * std::max(1.0, std::max(a, b)));
+}
+
+//============================================================================
+
 class AstNode;
 
 class V3Number {
diff --git a/src/V3Width.cpp b/src/V3Width.cpp
index df700b182..3b54e14cf 100644
--- a/src/V3Width.cpp
+++ b/src/V3Width.cpp
@@ -4342,9 +4342,12 @@ private:
             AstNRelinker linker;
             nodep->unlinkFrBack(&linker);
             if (AstConst* constp = VN_CAST(nodep, Const)) {
-                // Ignore obvious conversions of whole real numbers, e.g. 1.0 -> 1
+                // We convert to/from vlsint32 rather than use floor() as want to make sure is
+                // representable in integer's number of bits
                 if (constp->isDouble()
-                    && constp->num().toDouble() == floor(constp->num().toDouble())) {
+                    && v3EpsilonEqual(constp->num().toDouble(),
+                                      static_cast<double>(
+                                          static_cast<vlsint32_t>(constp->num().toDouble())))) {
                     warnOn = false;
                 }
             }