Bug 1619878 - Remove FlowsIntoNext and use BytecodeFallsThrough instead. r=arai

BytecodeFallsThrough is a bit more complete.

Differential Revision: https://phabricator.services.mozilla.com/D65298

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

js/src/debugger/Script.cpp

@@ -1102,7 +1102,7 @@ class FlowGraphSummary {
       size_t column = prevColumn;
       JSOp op = r.frontOpcode();
 
-      if (FlowsIntoNext(prevOp)) {
+      if (BytecodeFallsThrough(prevOp)) {
         addEdge(prevLineno, prevColumn, r.frontOffset());
       }
 

js/src/vm/BytecodeUtil.cpp

@@ -3038,7 +3038,7 @@ bool js::GetSuccessorBytecodes(JSScript* script, jsbytecode* pc,
   MOZ_ASSERT(script->containsPC(pc));
 
   JSOp op = (JSOp)*pc;
-  if (FlowsIntoNext(op)) {
+  if (BytecodeFallsThrough(op)) {
     if (!successors.append(GetNextPc(pc))) {
       return false;
     }

js/src/vm/BytecodeUtil.h

@@ -374,19 +374,20 @@ static inline uint32_t JOF_OPTYPE(JSOp op) {
 static inline bool IsJumpOpcode(JSOp op) { return JOF_OPTYPE(op) == JOF_JUMP; }
 
 static inline bool BytecodeFallsThrough(JSOp op) {
+  // Note:
+  // * JSOp::Yield/JSOp::Await is considered to fall through, like JSOp::Call.
+  // * JSOp::Gosub falls through indirectly, after executing a 'finally'.
   switch (op) {
     case JSOp::Goto:
     case JSOp::Default:
     case JSOp::Return:
     case JSOp::RetRval:
+    case JSOp::Retsub:
     case JSOp::FinalYieldRval:
     case JSOp::Throw:
     case JSOp::ThrowMsg:
     case JSOp::TableSwitch:
       return false;
-    case JSOp::Gosub:
-      /* These fall through indirectly, after executing a 'finally'. */
-      return true;
     default:
       return true;
   }
@@ -530,22 +531,6 @@ static inline bool BytecodeFlowsToBitop(jsbytecode* pc) {
 extern bool IsValidBytecodeOffset(JSContext* cx, JSScript* script,
                                   size_t offset);
 
-inline bool FlowsIntoNext(JSOp op) {
-  // JSOp::Yield/JSOp::Await is considered to flow into the next instruction,
-  // like JSOp::Call.
-  switch (op) {
-    case JSOp::RetRval:
-    case JSOp::Return:
-    case JSOp::Throw:
-    case JSOp::Goto:
-    case JSOp::Retsub:
-    case JSOp::FinalYieldRval:
-      return false;
-    default:
-      return true;
-  }
-}
-
 inline bool IsArgOp(JSOp op) { return JOF_OPTYPE(op) == JOF_QARG; }
 
 inline bool IsLocalOp(JSOp op) { return JOF_OPTYPE(op) == JOF_LOCAL; }