Bug 1629721 - Remove BytecodeEmitter::runOnceLambda helper. r=mgaudet

Instead rely on consistent definitions of the TreatAsRunOnce flag on the
SharedContext. Also simplify the BCE::check{RunOnce,Singleton}Context
accessors. Note that the TreatAsRunOnce flag indicates the script is expected
to run-once, but the BCE also checks for isInLoop to decide if current
bytecode location within the script should still be considered run-once.

Differential Revision: https://phabricator.services.mozilla.com/D70780

--HG--
extra : moz-landing-system : lando

js/src/frontend/BytecodeEmitter.cpp

@@ -1535,12 +1535,12 @@ bool BytecodeEmitter::isInLoop() {
   return findInnermostNestableControl<LoopControl>();
 }
 
-bool BytecodeEmitter::checkSingletonContext() {
-  return sc->treatAsRunOnce() && !sc->isFunctionBox() && !isInLoop();
+bool BytecodeEmitter::checkRunOnceContext() {
+  return sc->treatAsRunOnce() && !isInLoop();
 }
 
-bool BytecodeEmitter::checkRunOnceContext() {
-  return checkSingletonContext() || (!isInLoop() && isRunOnceLambda());
+bool BytecodeEmitter::checkSingletonContext() {
+  return sc->isTopLevelContext() && checkRunOnceContext();
 }
 
 bool BytecodeEmitter::needsImplicitThis() {
@@ -2190,15 +2190,6 @@ MOZ_NEVER_INLINE bool BytecodeEmitter::emitSwitch(SwitchStatement* switchStmt) {
   return true;
 }
 
-bool BytecodeEmitter::isRunOnceLambda() {
-  if (emitterMode == LazyFunction) {
-    return sc->treatAsRunOnce();
-  }
-
-  return parent && parent->emittingRunOnceLambda &&
-         !sc->asFunctionBox()->shouldSuppressRunOnce();
-}
-
 bool BytecodeEmitter::allocateResumeIndex(BytecodeOffset offset,
                                           uint32_t* resumeIndex) {
   static constexpr uint32_t MaxResumeIndex = BitMask(24);

js/src/frontend/BytecodeEmitter.h

@@ -142,8 +142,6 @@ struct MOZ_STACK_CLASS BytecodeEmitter {
   // True while emitting a lambda which is only expected to run once.
   bool emittingRunOnceLambda = false;
 
-  bool isRunOnceLambda();
-
   enum EmitterMode {
     Normal,