Bug 1530745 - Part 6: Change JSOP_RESUME immediate back to UINT8. r=arai

And add more assertions to document implicit requirements about opcode lengths.

Depends on D22670

Differential Revision: https://phabricator.services.mozilla.com/D22671

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

js/src/frontend/BytecodeEmitter.cpp

@@ -7128,11 +7128,11 @@ bool BytecodeEmitter::emitSelfHostedResumeGenerator(BinaryNode* callNode) {
 
   ParseNode* kindNode = valNode->pn_next;
   MOZ_ASSERT(kindNode->isKind(ParseNodeKind::StringExpr));
-  uint16_t operand = AbstractGeneratorObject::getResumeKind(
+  uint8_t operand = AbstractGeneratorObject::getResumeKind(
       cx, kindNode->as<NameNode>().atom());
   MOZ_ASSERT(!kindNode->pn_next);
 
-  if (!emitCall(JSOP_RESUME, operand)) {
+  if (!emit2(JSOP_RESUME, operand)) {
     return false;
   }
 

js/src/vm/GeneratorObject.cpp

@@ -319,6 +319,11 @@ bool AbstractGeneratorObject::isAfterYieldOrAwait(JSOp op) {
     return false;
   }
 
+  static_assert(JSOP_YIELD_LENGTH == JSOP_INITIALYIELD_LENGTH,
+                "JSOP_YIELD and JSOP_INITIALYIELD must have the same length");
+  static_assert(JSOP_YIELD_LENGTH == JSOP_AWAIT_LENGTH,
+                "JSOP_YIELD and JSOP_AWAIT must have the same length");
+
   uint32_t offset = nextOffset - JSOP_YIELD_LENGTH;
   MOZ_ASSERT(code[offset] == JSOP_INITIALYIELD || code[offset] == JSOP_YIELD ||
              code[offset] == JSOP_AWAIT);

js/src/vm/GeneratorObject.h

@@ -41,7 +41,7 @@ class AbstractGeneratorObject : public NativeObject {
  public:
   static inline ResumeKind getResumeKind(jsbytecode* pc) {
     MOZ_ASSERT(*pc == JSOP_RESUME);
-    unsigned arg = GET_UINT16(pc);
+    unsigned arg = GET_UINT8(pc);
     MOZ_ASSERT(arg <= RETURN);
     return static_cast<ResumeKind>(arg);
   }

js/src/vm/Interpreter.cpp

@@ -2111,6 +2111,10 @@ static MOZ_NEVER_INLINE JS_HAZ_JSNATIVE_CALLER bool Interpret(JSContext* cx,
         if (MOZ_LIKELY(interpReturnOK)) {
           TypeScript::Monitor(cx, script, REGS.pc, REGS.sp[-1]);
 
+          if (JSOp(*REGS.pc) == JSOP_RESUME) {
+            ADVANCE_AND_DISPATCH(JSOP_RESUME_LENGTH);
+          }
+          MOZ_ASSERT(CodeSpec[*REGS.pc].length == JSOP_CALL_LENGTH);
           ADVANCE_AND_DISPATCH(JSOP_CALL_LENGTH);
         }
 
@@ -3024,6 +3028,19 @@ static MOZ_NEVER_INLINE JS_HAZ_JSNATIVE_CALLER bool Interpret(JSContext* cx,
     CASE(JSOP_CALLITER)
     CASE(JSOP_SUPERCALL)
     CASE(JSOP_FUNCALL) {
+      static_assert(JSOP_CALL_LENGTH == JSOP_NEW_LENGTH,
+                    "call and new must be the same size");
+      static_assert(JSOP_CALL_LENGTH == JSOP_CALL_IGNORES_RV_LENGTH,
+                    "call and call-ignores-rv must be the same size");
+      static_assert(JSOP_CALL_LENGTH == JSOP_CALLITER_LENGTH,
+                    "call and calliter must be the same size");
+      static_assert(JSOP_CALL_LENGTH == JSOP_SUPERCALL_LENGTH,
+                    "call and supercall must be the same size");
+      static_assert(JSOP_CALL_LENGTH == JSOP_FUNCALL_LENGTH,
+                    "call and funcall must be the same size");
+      static_assert(JSOP_CALL_LENGTH == JSOP_FUNAPPLY_LENGTH,
+                    "call and funapply must be the same size");
+
       if (REGS.fp()->hasPushedGeckoProfilerFrame()) {
         cx->geckoProfiler().updatePC(cx, script, REGS.pc);
       }

js/src/vm/Opcodes.h

@@ -2220,7 +2220,7 @@
      *   Operands: resume kind (AbstractGeneratorObject::ResumeKind)
      *   Stack: gen, val => rval
      */ \
-    MACRO(JSOP_RESUME, 205, "resume", NULL, 3, 2, 1, JOF_UINT16|JOF_INVOKE) \
+    MACRO(JSOP_RESUME, 205, "resume", NULL, 2, 2, 1, JOF_UINT8|JOF_INVOKE) \
     /*
      * Load the callee stored in a CallObject on the environment chain. The
      * numHops operand is the number of environment objects to skip on the