From a4a29e29c3f1eed18f851dcf10bdc845571dfcb6 Mon Sep 17 00:00:00 2001
From: Andrew Waterman
Date: Fri, 12 Apr 2019 17:51:04 -0700
Subject: Avoid silently truncating BigInt to Int

- Introduce internal helper `castToInt`, which issues an error when the input
BigInt can't be represented as Int.

- Use `castToInt` wherever we were using `toInt` in a potentially unsafe way.
---
 chiselFrontend/src/main/scala/chisel3/internal/Builder.scala | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'chiselFrontend/src/main/scala/chisel3/internal')

diff --git a/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala b/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
index 4105a699..1163171c 100644
--- a/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
+++ b/chiselFrontend/src/main/scala/chisel3/internal/Builder.scala
@@ -378,3 +378,12 @@ object DynamicNamingStack {
     prefixRef
   }
 }
+
+/** Casts BigInt to Int, issuing an error when the input isn't representable. */
+private[chisel3] object castToInt {
+  def apply(x: BigInt, msg: String): Int = {
+    val res = x.toInt
+    require(x == res, s"$msg $x is too large to be represented as Int")
+    res
+  }
+}
-- 
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