propagate emit-async-break-check at runtime

Summary:
Propagate the value of `emit-async-break-check` to the VM runtime using
a new runtime flag. This ensures that the async break check will work in
code generated by eval() or new Function().

Additionally, save the flag in hermes::facebook::HermesRuntimeImpl so it
can be applied by default to all source compiled using the JSI
interface.

Reviewed By: avp

Differential Revision: D26031515

fbshipit-source-id: 41fb96c7997f2c78c4e4d24e36cbc70b4403b8a0

API/hermes/hermes.cpp

@@ -309,6 +309,8 @@ class HermesRuntimeImpl final : public HermesRuntime,
     }
 
     compileFlags_.enableGenerator = runtimeConfig.getEnableGenerator();
+    compileFlags_.emitAsyncBreakCheck = defaultEmitAsyncBreakCheck_ =
+        runtimeConfig.getAsyncBreakCheckInEval();
 
 #ifndef HERMESJSI_ON_STACK
     // Register the memory for the runtime if it isn't stored on the stack.
@@ -1069,6 +1071,8 @@ class HermesRuntimeImpl final : public HermesRuntime,
 
   /// Compilation flags used by prepareJavaScript().
   ::hermes::hbc::CompileFlags compileFlags_{};
+  /// The default setting of "emit async break check" in this runtime.
+  bool defaultEmitAsyncBreakCheck_{false};
 };
 
 namespace {
@@ -1296,7 +1300,9 @@ void HermesRuntime::watchTimeLimit(uint32_t timeoutInMs) {
 }
 
 void HermesRuntime::unwatchTimeLimit() {
-  impl(this)->compileFlags_.emitAsyncBreakCheck = false;
+  // Restore the default state.
+  impl(this)->compileFlags_.emitAsyncBreakCheck =
+      impl(this)->defaultEmitAsyncBreakCheck_;
   ::hermes::vm::TimeLimitMonitor::getInstance().unwatchRuntime(
       &(impl(this)->runtime_));
 }

include/hermes/CompilerDriver/CompilerDriver.h

@@ -99,5 +99,6 @@ extern llvh::cl::opt<bool> EmitAsyncBreakCheck;
 extern llvh::cl::opt<bool> AllowFunctionToString;
 extern llvh::cl::list<std::string> InputFilenames;
 extern llvh::cl::opt<bool> OptimizedEval;
+extern llvh::cl::opt<bool> EmitAsyncBreakCheck;
 } // namespace cl
 #endif

include/hermes/VM/Runtime.h

@@ -673,12 +673,14 @@ class Runtime : public HandleRootOwner,
   RegExpMatch regExpLastMatch{};
 
   /// Whether to allow eval and Function ctor.
-  const bool enableEval;
+  const bool enableEval : 1;
   /// Whether to verify the IR being generated by eval and the Function ctor.
-  const bool verifyEvalIR;
+  const bool verifyEvalIR : 1;
   /// Whether to optimize the code in the string passed to eval and the Function
   /// ctor.
-  const bool optimizedEval;
+  const bool optimizedEval : 1;
+  /// Whether to emit async break check instructions in eval().
+  const bool asyncBreakCheckInEval : 1;
 
 #ifdef HERMESVM_PROFILER_OPCODE
   /// Track the frequency of each opcode in the interpreter.

lib/VM/JSLib/eval.cpp

@@ -46,6 +46,8 @@ CallResult<HermesValue> evalInEnvironment(
   compileFlags.strict = false;
   compileFlags.includeLibHermes = false;
   compileFlags.optimize = runtime->optimizedEval;
+  compileFlags.verifyIR = runtime->verifyEvalIR;
+  compileFlags.emitAsyncBreakCheck = runtime->asyncBreakCheckInEval;
   compileFlags.lazy =
       utf8code.size() >= compileFlags.preemptiveFileCompilationThreshold;
   compileFlags.allowFunctionToStringWithRuntimeSource =

lib/VM/Runtime.cpp

@@ -149,6 +149,7 @@ Runtime::Runtime(
     : enableEval(runtimeConfig.getEnableEval()),
       verifyEvalIR(runtimeConfig.getVerifyEvalIR()),
       optimizedEval(runtimeConfig.getOptimizedEval()),
+      asyncBreakCheckInEval(runtimeConfig.getAsyncBreakCheckInEval()),
       heap_(
           getMetadataTable(),
           this,

public/hermes/Public/RuntimeConfig.h

@@ -62,6 +62,9 @@ class Deserializer;
   /* Whether to optimize the code inside eval and Function ctor */             \
   F(constexpr, bool, OptimizedEval, false)                                     \
                                                                                \
+  /* Whether to emit async break check instructions in eval code */            \
+  F(constexpr, bool, AsyncBreakCheckInEval, false)                             \
+                                                                               \
   /* Support for ES6 Promise. */                                               \
   F(constexpr, bool, ES6Promise, true)                                         \
                                                                                \

test/hermes/execution-time-limit-eval.js

@@ -0,0 +1,29 @@
+/**
+ * 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 -w -O0 -emit-async-break-check -time-limit=300 %s 2>&1 ) | %FileCheck --match-full-lines %s
+
+eval(`
+function entryPoint() {
+  helper();
+}
+
+function helper() {
+  var i = 0;
+  while (true) {
+    ++i;
+  }
+}
+
+entryPoint();
+`);
+
+//CHECK:Uncaught TimeoutError: Javascript execution has timed out.
+//CHECK-NEXT:    at helper {{.*}}
+//CHECK-NEXT:    at entryPoint {{.*}}
+//CHECK-NEXT:    at eval {{.*}}
+//CHECK-NEXT:    at global {{.*}}

test/hermes/execution-time-limit.js

@@ -5,7 +5,8 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-// RUN: (! %hermes -O0 -emit-async-break-check -time-limit=1000 %s 2>&1 ) | %FileCheck --match-full-lines %s
+// RUN: (! %hermes -O0 -emit-async-break-check -time-limit=300 %s 2>&1 ) | %FileCheck --match-full-lines %s
+// RUN: (! %hermes -O0 -emit-async-break-check -time-limit=300 -lazy %s 2>&1 ) | %FileCheck --match-full-lines %s
 
 function entryPoint() {
   helper();
@@ -21,6 +22,6 @@ function helper() {
 entryPoint();
 
 //CHECK: Uncaught TimeoutError: Javascript execution has timed out.
-//CHECK: at helper ({{.*/execution-time-limit.js}}:17:5)
-//CHECK-NEXT: at entryPoint ({{.*/execution-time-limit.js}}:11:9)
-//CHECK-NEXT: at global ({{.*/execution-time-limit.js}}:21:11)
+//CHECK: at helper ({{.*/execution-time-limit.js}}:18:5)
+//CHECK-NEXT: at entryPoint ({{.*/execution-time-limit.js}}:12:9)
+//CHECK-NEXT: at global ({{.*/execution-time-limit.js}}:22:11)

tools/hermes/hermes.cpp

@@ -118,6 +118,7 @@ static int executeHBCBytecodeFromCL(
           .withEnableEval(cl::EnableEval)
           .withVerifyEvalIR(cl::VerifyIR)
           .withOptimizedEval(cl::OptimizedEval)
+          .withAsyncBreakCheckInEval(cl::EmitAsyncBreakCheck)
           .withVMExperimentFlags(cl::VMExperimentFlags)
           .withES6Promise(cl::ES6Promise)
           .withES6Proxy(cl::ES6Proxy)