From e55c00fe09a795adae15b6383a75300d6cfa9e7a Mon Sep 17 00:00:00 2001
From: Jim Lawson
Date: Wed, 8 Apr 2020 08:44:48 -0700
Subject: Use thread local storage for ChiselContext. (#1404)

---
 core/src/main/scala/chisel3/internal/Builder.scala | 37 ++++++++++++----------
 1 file changed, 20 insertions(+), 17 deletions(-)

(limited to 'core/src')

diff --git a/core/src/main/scala/chisel3/internal/Builder.scala b/core/src/main/scala/chisel3/internal/Builder.scala
index 773a9ad1..7e521812 100644
--- a/core/src/main/scala/chisel3/internal/Builder.scala
+++ b/core/src/main/scala/chisel3/internal/Builder.scala
@@ -231,7 +231,12 @@ private[chisel3] object Builder {
     dynamicContextVar.value.get
   }
 
-  private val chiselContext = new DynamicVariable[ChiselContext](new ChiselContext)
+  // Ensure we have a thread-specific ChiselContext
+  private val chiselContext = new ThreadLocal[ChiselContext]{
+    override def initialValue: ChiselContext = {
+      new ChiselContext
+    }
+  }
 
   // Initialize any singleton objects before user code inadvertently inherits them.
   private def initializeSingletons(): Unit = {
@@ -247,7 +252,7 @@ private[chisel3] object Builder {
 
   def namingStackOption: Option[NamingStack] = dynamicContextVar.value.map(_.namingStack)
 
-  def idGen: IdGen = chiselContext.value.idGen
+  def idGen: IdGen = chiselContext.get.idGen
 
   def globalNamespace: Namespace = dynamicContext.globalNamespace
   def components: ArrayBuffer[Component] = dynamicContext.components
@@ -348,18 +353,18 @@ private[chisel3] object Builder {
     // Prune the existing Bundle stack of closed Bundles
     // If we know where we are in the stack, discard frames above that
     val stackEltsTop = if (eltStackPos >= 0) eltStackPos else stackElts.size
-    val pruneLength = chiselContext.value.bundleStack.reverse.prefixLength { case (_, cname, mname, pos) =>
+    val pruneLength = chiselContext.get.bundleStack.reverse.prefixLength { case (_, cname, mname, pos) =>
       pos >= stackEltsTop || stackElts(pos).getClassName != cname || stackElts(pos).getMethodName != mname
     }
-    chiselContext.value.bundleStack.trimEnd(pruneLength)
+    chiselContext.get.bundleStack.trimEnd(pruneLength)
 
     // Return the stack state before adding the most recent bundle
-    val lastStack = chiselContext.value.bundleStack.map(_._1).toSeq
+    val lastStack = chiselContext.get.bundleStack.map(_._1).toSeq
 
     // Append the current Bundle to the stack, if it's on the stack trace
     if (eltStackPos >= 0) {
       val stackElt = stackElts(eltStackPos)
-      chiselContext.value.bundleStack.append((elt, eltClassName, stackElt.getMethodName, eltStackPos))
+      chiselContext.get.bundleStack.append((elt, eltClassName, stackElt.getMethodName, eltStackPos))
     }
     // Otherwise discard the stack frame, this shouldn't fail noisily
 
@@ -398,17 +403,15 @@ private[chisel3] object Builder {
   }
 
   def build[T <: RawModule](f: => T): (Circuit, T) = {
-    chiselContext.withValue(new ChiselContext) {
-      dynamicContextVar.withValue(Some(new DynamicContext())) {
-        errors.info("Elaborating design...")
-        val mod = f
-        mod.forceName(mod.name, globalNamespace)
-        errors.checkpoint()
-        errors.info("Done elaborating.")
-
-        (Circuit(components.last.name, components, annotations), mod)
-      }
-   }
+    dynamicContextVar.withValue(Some(new DynamicContext())) {
+      errors.info("Elaborating design...")
+      val mod = f
+      mod.forceName(mod.name, globalNamespace)
+      errors.checkpoint()
+      errors.info("Done elaborating.")
+
+      (Circuit(components.last.name, components, annotations), mod)
+    }
   }
   initializeSingletons()
 }
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