Correctly restore whether or not a function is an inner generator

Summary: If a generator was large enough to be lazily compiled, we would lose that information when reconstituting the function's context. This meant the function was generated as a regular function instead of a generator. #utd-hermes-ignore-android Reviewed By: tmikov Differential Revision: D23580247 fbshipit-source-id: af5628bf322cbdc7c7cdfbb5f8d0756328518ea1
facebook · Sep 8, 2020 · 0918353 · 0918353
1 parent cba0416
commit 0918353
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Showing 8 changed files with 64 additions and 21 deletions.
diff --git a/include/hermes/IR/IR.h b/include/hermes/IR/IR.h
@@ -336,8 +336,10 @@ class SerializedScope {
 #ifndef HERMESVM_LEAN
 /// The source of a lazy AST node.
 struct LazySource {
-  // The type of node (such as a FunctionDeclaration or FunctionExpression).
+  /// The type of node (such as a FunctionDeclaration or FunctionExpression).
   ESTree::NodeKind nodeKind{ESTree::NodeKind::Empty};
+  /// Whether or not this is the inner function of a generator
+  bool isGeneratorInnerFunction;
   /// The source buffer id in which this function can be find.
   uint32_t bufferId{0};
   /// The range of the function within the buffer (the whole function node, not

diff --git a/include/hermes/IRGen/IRGen.h b/include/hermes/IRGen/IRGen.h
@@ -42,6 +42,9 @@ struct LazyCompilationData {
   /// The type of function, e.g. statement or expression.
   ESTree::NodeKind nodeKind;
 
+  /// Whether or not this is the inner function of a generator.
+  bool isGeneratorInnerFunction;
+
   /// Whether or not the function is strict.
   bool strictMode;
 };

diff --git a/lib/BCGen/HBC/BytecodeGenerator.cpp b/lib/BCGen/HBC/BytecodeGenerator.cpp
@@ -278,6 +278,8 @@ std::unique_ptr<BytecodeModule> BytecodeModuleGenerator::generate() {
       auto lazyData = llvh::make_unique<LazyCompilationData>();
       lazyData->parentScope = F->getLazyScope();
       lazyData->nodeKind = F->getLazySource().nodeKind;
+      lazyData->isGeneratorInnerFunction =
+          F->getLazySource().isGeneratorInnerFunction;
       lazyData->bufferId = F->getLazySource().bufferId;
       lazyData->originalName = F->getOriginalOrInferredName();
       lazyData->closureAlias = F->getLazyClosureAlias()

diff --git a/lib/IRGen/ESTreeIRGen-func.cpp b/lib/IRGen/ESTreeIRGen-func.cpp
@@ -215,6 +215,7 @@ Function *ESTreeIRGen::genES5Function(
       auto &lazySource = newFunction->getLazySource();
       lazySource.bufferId = bodyBlock->bufferId;
       lazySource.nodeKind = getLazyFunctionKind(functionNode);
+      lazySource.isGeneratorInnerFunction = isGeneratorInnerFunction;
       lazySource.functionRange = functionNode->getSourceRange();
 
       // Set the function's .length.
@@ -302,14 +303,17 @@ Function *ESTreeIRGen::genGeneratorFunction(
       ESTree::isStrict(functionNode->strictness),
       /* insertBefore */ nullptr);
 
-  auto *innerFn = genES5Function(
-      genAnonymousLabelName(originalName.isValid() ? originalName.str() : ""),
-      lazyClosureAlias,
-      functionNode,
-      true);
-
   {
     FunctionContext outerFnContext{this, outerFn, functionNode->getSemInfo()};
+
+    // Build the inner function. This must be done in the outerFnContext
+    // since it's lexically considered a child function.
+    auto *innerFn = genES5Function(
+        genAnonymousLabelName(originalName.isValid() ? originalName.str() : ""),
+        lazyClosureAlias,
+        functionNode,
+        true);
+
     emitFunctionPrologue(
         functionNode,
         Builder.createBasicBlock(outerFn),

diff --git a/lib/IRGen/ESTreeIRGen.cpp b/lib/IRGen/ESTreeIRGen.cpp
@@ -349,7 +349,11 @@ std::pair<Function *, Function *> ESTreeIRGen::doLazyFunction(
       !llvh::isa<ESTree::ArrowFunctionExpressionNode>(node) &&
       "lazy compilation not supported for arrow functions");
 
-  auto *func = genES5Function(lazyData->originalName, parentVar, node);
+  auto *func = genES5Function(
+      lazyData->originalName,
+      parentVar,
+      node,
+      lazyData->isGeneratorInnerFunction);
   addLexicalDebugInfo(func, topLevel, lexicalScopeChain);
   return {func, topLevel};
 }

diff --git a/test/BCGen/HBC/es6/generator.js b/test/BCGen/HBC/es6/generator.js
@@ -74,7 +74,7 @@ function *args() {
 // CHECK-NEXT:     CreateGenerator   r1, r0, 4
 // CHECK-NEXT:     Ret               r1
 
-// CHECK-LABEL: Function<?anon_1_args>(1 params, 7 registers, 0 symbols):
+// CHECK-LABEL: Function<?anon_0_args>(1 params, 7 registers, 0 symbols):
 // CHECK-NEXT: Offset in debug table: source 0x{{.*}}, lexical 0x0000
 // CHECK-NEXT:     StartGenerator
 // CHECK-NEXT:     CreateEnvironment r0

diff --git a/test/IRGen/es6/generator.js b/test/IRGen/es6/generator.js
@@ -47,11 +47,11 @@ function *useResult() {
 //CHECK-NEXT:frame = [x]
 //CHECK-NEXT:%BB0:
 //CHECK-NEXT:  %0 = StoreFrameInst undefined : undefined, [x]
-//CHECK-NEXT:  %1 = CreateGeneratorInst %?anon_1_useResult()
+//CHECK-NEXT:  %1 = CreateGeneratorInst %?anon_0_useResult()
 //CHECK-NEXT:  %2 = ReturnInst %1 : object
 //CHECK-NEXT:function_end
 
-//CHECK-LABEL:function ?anon_1_useResult()
+//CHECK-LABEL:function ?anon_0_useResult()
 //CHECK-NEXT:frame = [x]
 //CHECK-NEXT:%BB0:
 //CHECK-NEXT:  %0 = StartGeneratorInst
@@ -86,11 +86,11 @@ function *loop(x) {
 //CHECK-NEXT:frame = [i]
 //CHECK-NEXT:%BB0:
 //CHECK-NEXT:  %0 = StoreFrameInst undefined : undefined, [i]
-//CHECK-NEXT:  %1 = CreateGeneratorInst %?anon_2_loop()
+//CHECK-NEXT:  %1 = CreateGeneratorInst %?anon_0_loop()
 //CHECK-NEXT:  %2 = ReturnInst %1 : object
 //CHECK-NEXT:function_end
 
-//CHECK-LABEL:function ?anon_2_loop(x)
+//CHECK-LABEL:function ?anon_0_loop(x)
 //CHECK-NEXT:frame = [i, x]
 //CHECK-NEXT:%BB0:
 //CHECK-NEXT:  %0 = StartGeneratorInst
@@ -139,11 +139,11 @@ var simple2 = function*() {
 //CHECK-LABEL:function simple2()
 //CHECK-NEXT:frame = []
 //CHECK-NEXT:%BB0:
-//CHECK-NEXT:  %0 = CreateGeneratorInst %?anon_4_simple2()
+//CHECK-NEXT:  %0 = CreateGeneratorInst %?anon_0_simple2()
 //CHECK-NEXT:  %1 = ReturnInst %0 : object
 //CHECK-NEXT:function_end
 
-//CHECK-LABEL:function ?anon_4_simple2()
+//CHECK-LABEL:function ?anon_0_simple2()
 //CHECK-NEXT:frame = []
 //CHECK-NEXT:%BB0:
 //CHECK-NEXT:  %0 = StartGeneratorInst
@@ -172,11 +172,11 @@ var yieldStar = function*() {
 //CHECK-LABEL:function yieldStar()
 //CHECK-NEXT:frame = []
 //CHECK-NEXT:%BB0:
-//CHECK-NEXT:  %0 = CreateGeneratorInst %?anon_5_yieldStar()
+//CHECK-NEXT:  %0 = CreateGeneratorInst %?anon_0_yieldStar()
 //CHECK-NEXT:  %1 = ReturnInst %0 : object
 //CHECK-NEXT:function_end
 
-//CHECK-LABEL:function ?anon_5_yieldStar()
+//CHECK-LABEL:function ?anon_0_yieldStar()
 //CHECK-NEXT:frame = []
 //CHECK-NEXT:%BB0:
 //CHECK-NEXT:  %0 = StartGeneratorInst
@@ -281,13 +281,13 @@ var destr = function*([x]) {
 //CHECK-LABEL:function destr()
 //CHECK-NEXT:frame = []
 //CHECK-NEXT:%BB0:
-//CHECK-NEXT:  %0 = CreateGeneratorInst %?anon_6_destr()
+//CHECK-NEXT:  %0 = CreateGeneratorInst %?anon_0_destr()
 //CHECK-NEXT:  %1 = LoadPropertyInst %0 : object, "next" : string
 //CHECK-NEXT:  %2 = CallInst %1, %0 : object
 //CHECK-NEXT:  %3 = ReturnInst %0 : object
 //CHECK-NEXT:function_end
 
-//CHECK-LABEL:function ?anon_6_destr(?anon_2_param)
+//CHECK-LABEL:function ?anon_0_destr(?anon_2_param)
 //CHECK-NEXT:frame = [x]
 //CHECK-NEXT:%BB0:
 //CHECK-NEXT:  %0 = StartGeneratorInst
@@ -355,13 +355,13 @@ var initializer = function*(x = foo()) {
 //CHECK-LABEL:function initializer()
 //CHECK-NEXT:frame = []
 //CHECK-NEXT:%BB0:
-//CHECK-NEXT:  %0 = CreateGeneratorInst %?anon_7_initializer()
+//CHECK-NEXT:  %0 = CreateGeneratorInst %?anon_0_initializer()
 //CHECK-NEXT:  %1 = LoadPropertyInst %0 : object, "next" : string
 //CHECK-NEXT:  %2 = CallInst %1, %0 : object
 //CHECK-NEXT:  %3 = ReturnInst %0 : object
 //CHECK-NEXT:function_end
 
-//CHECK-LABEL:function ?anon_7_initializer(x)
+//CHECK-LABEL:function ?anon_0_initializer(x)
 //CHECK-NEXT:frame = [x]
 //CHECK-NEXT:%BB0:
 //CHECK-NEXT:  %0 = StartGeneratorInst

diff --git a/test/IRGen/lazy-function-in-generator.js b/test/IRGen/lazy-function-in-generator.js
@@ -0,0 +1,28 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// RUN: %hermes -lazy %s | %FileCheck %s --match-full-lines
+
+// Make sure we can correctly resolve scopes through lazily compiled
+// functions in lazily compiled generators.
+function f() {
+  var f_var = 10;
+  function* g() {
+    var g_var = 32;
+    function h() {
+      /* Some text to pad out the function so that it won't be eagerly compiled
+       * for being too short. Lorem ipsum dolor sit amet, consectetur adipiscing
+       * elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
+       */
+      return f_var + g_var;
+    }
+    yield h();
+  }
+  return g().next().value;
+}
+// CHECK: 42
+print(f());