---

yaml
---
r: 326591
b: refs/heads/tensorflow
c: 90a5ac2
h: refs/heads/master
i:
  326589: 8f4a2ad
  326587: 23b62ad
  326583: 623179c
  326575: 0b12ec8
  326559: 08d38cb
  326527: e67cc5e

Author: adrian-prantl

[refs]

@@ -816,7 +816,7 @@ refs/tags/swift-DEVELOPMENT-SNAPSHOT-2018-04-25-a: 22f738a831d43aff2b9c9773bcb65
 refs/tags/swift-DEVELOPMENT-SNAPSHOT-2018-05-08-a: 7d98cc16689baba5c8a3b90a9329bdcc1a12b4e9
 refs/heads/cherr42: a566ad54b073c2c56ac0a705d0a5bed9743135a5
 "refs/heads/codable_test_comment_fix": fc8f6824f7f347e1e8db55bff62db385c5728b5a
-refs/heads/tensorflow: eb740be819735d6ccdc3d76e3f32f3fc1d4ed6f9
+refs/heads/tensorflow: 90a5ac265d2ea3b98f013693e44c4686a23db220
 refs/tags/swift-4.1-DEVELOPMENT-SNAPSHOT-2018-05-11-a: 8126fd7a652e2f70ad6d76505239e34fb2ef3e1a
 refs/tags/swift-4.1-DEVELOPMENT-SNAPSHOT-2018-05-12-a: b3fd3dd84df6717f2e2e9df58c6d7e99fed57086
 refs/tags/swift-4.1-DEVELOPMENT-SNAPSHOT-2018-05-13-a: 71135119579039dc321c5f65d870050fe36efda2

branches/tensorflow/include/swift/Basic/Statistics.def

@@ -166,6 +166,11 @@ FRONTEND_STATISTIC(Sema, NumLeafScopes)
 /// This is a measure of complexity of the contraction algorithm.
 FRONTEND_STATISTIC(Sema, NumConstraintsConsideredForEdgeContraction)
 
+/// Number of constraint-solving scopes created in the typechecker, while
+/// solving expression type constraints. A rough proxy for "how much work the
+/// expression typechecker did".
+FRONTEND_STATISTIC(Sema, NumCyclicOneWayComponentsCollapsed)
+
 /// Number of declarations that were deserialized. A rough proxy for the amount
 /// of material loaded from other modules.
 FRONTEND_STATISTIC(Sema, NumDeclsDeserialized)

branches/tensorflow/lib/Sema/BuilderTransform.cpp

@@ -52,7 +52,8 @@ class BuilderClosureVisitor
   /// Produce a builder call to the given named function with the given arguments.
   Expr *buildCallIfWanted(SourceLoc loc,
                           Identifier fnName, ArrayRef<Expr *> args,
-                          ArrayRef<Identifier> argLabels = {}) {
+                          ArrayRef<Identifier> argLabels,
+                          bool allowOneWay) {
     if (!wantExpr)
       return nullptr;
 
@@ -86,7 +87,7 @@ class BuilderClosureVisitor
                                     /*trailing closure*/ nullptr,
                                     /*implicit*/true);
 
-    if (ctx.LangOpts.FunctionBuilderOneWayConstraints) {
+    if (ctx.LangOpts.FunctionBuilderOneWayConstraints && allowOneWay) {
       // Form a one-way constraint to prevent backward propagation.
       result = new (ctx) OneWayExpr(result);
     }
@@ -176,7 +177,9 @@ class BuilderClosureVisitor
 
     // Call Builder.buildBlock(... args ...)
     return buildCallIfWanted(braceStmt->getStartLoc(),
-                             ctx.Id_buildBlock, expressions);
+                             ctx.Id_buildBlock, expressions,
+                             /*argLabels=*/{ },
+                             /*allowOneWay=*/true);
   }
 
   Expr *visitReturnStmt(ReturnStmt *stmt) {
@@ -201,7 +204,8 @@ class BuilderClosureVisitor
     if (!arg)
       return nullptr;
 
-    return buildCallIfWanted(doStmt->getStartLoc(), ctx.Id_buildDo, arg);
+    return buildCallIfWanted(doStmt->getStartLoc(), ctx.Id_buildDo, arg,
+                             /*argLabels=*/{ }, /*allowOneWay=*/true);
   }
 
   CONTROL_FLOW_STMT(Yield)
@@ -286,7 +290,12 @@ class BuilderClosureVisitor
     // so we just need to call `buildIf` now, since we're at the top level.
     if (isOptional) {
       chainExpr = buildCallIfWanted(ifStmt->getStartLoc(),
-                                    ctx.Id_buildIf, chainExpr);
+                                    ctx.Id_buildIf, chainExpr,
+                                    /*argLabels=*/{ },
+                                    /*allowOneWay=*/true);
+    } else if (ctx.LangOpts.FunctionBuilderOneWayConstraints) {
+      // Form a one-way constraint to prevent backward propagation.
+      chainExpr = new (ctx) OneWayExpr(chainExpr);
     }
 
     return chainExpr;
@@ -406,7 +415,8 @@ class BuilderClosureVisitor
       bool isSecond = (path & 1);
       operand = buildCallIfWanted(operand->getStartLoc(),
                                   ctx.Id_buildEither, operand,
-                                  {isSecond ? ctx.Id_second : ctx.Id_first});
+                                  {isSecond ? ctx.Id_second : ctx.Id_first},
+                                  /*allowOneWay=*/false);
     }
 
     // Inject into Optional if required.  We'll be adding the call to