Bug 1032869 - Part 5: Add JSOP_DEBUGAFTERYIELD to fix up resumed generator BaselineFrames. (r=jandem)

js/src/frontend/BytecodeEmitter.cpp

@@ -3017,7 +3017,10 @@ EmitYieldOp(ExclusiveContext *cx, BytecodeEmitter *bce, JSOp op)
 
     SET_UINT24(bce->code(off), yieldIndex);
 
-    return bce->yieldOffsetList.append(bce->offset());
+    if (!bce->yieldOffsetList.append(bce->offset()))
+        return false;
+
+    return Emit1(cx, bce, JSOP_DEBUGAFTERYIELD) >= 0;
 }
 
 bool

js/src/jit/BaselineCompiler.cpp

@@ -3405,6 +3405,22 @@ BaselineCompiler::emit_JSOP_YIELD()
     return emitReturn();
 }
 
+typedef bool (*DebugAfterYieldFn)(JSContext *, BaselineFrame *);
+static const VMFunction DebugAfterYieldInfo = FunctionInfo<DebugAfterYieldFn>(jit::DebugAfterYield);
+
+bool
+BaselineCompiler::emit_JSOP_DEBUGAFTERYIELD()
+{
+    if (!compileDebugInstrumentation_)
+        return true;
+
+    frame.assertSyncedStack();
+    masm.loadBaselineFramePtr(BaselineFrameReg, R0.scratchReg());
+    prepareVMCall();
+    pushArg(R0.scratchReg());
+    return callVM(DebugAfterYieldInfo);
+}
+
 typedef bool (*FinalSuspendFn)(JSContext *, HandleObject, BaselineFrame *, jsbytecode *);
 static const VMFunction FinalSuspendInfo = FunctionInfo<FinalSuspendFn>(jit::FinalSuspend);
 

js/src/jit/BaselineCompiler.h

@@ -176,6 +176,7 @@ namespace jit {
     _(JSOP_GENERATOR)          \
     _(JSOP_INITIALYIELD)       \
     _(JSOP_YIELD)              \
+    _(JSOP_DEBUGAFTERYIELD)    \
     _(JSOP_FINALYIELDRVAL)     \
     _(JSOP_RESUME)             \
     _(JSOP_CALLEE)             \

js/src/jit/VMFunctions.cpp

@@ -907,6 +907,16 @@ InterpretResume(JSContext *cx, HandleObject obj, HandleValue val, HandleProperty
     return true;
 }
 
+bool
+DebugAfterYield(JSContext *cx, BaselineFrame *frame)
+{
+    // The BaselineFrame has just been constructed by JSOP_RESUME in the
+    // caller. We need to set its debuggee flag as necessary.
+    if (frame->script()->isDebuggee())
+        frame->setIsDebuggee();
+    return true;
+}
+
 bool
 StrictEvalPrologue(JSContext *cx, BaselineFrame *frame)
 {

js/src/jit/VMFunctions.h

@@ -712,6 +712,7 @@ bool NormalSuspend(JSContext *cx, HandleObject obj, BaselineFrame *frame, jsbyte
 bool FinalSuspend(JSContext *cx, HandleObject obj, BaselineFrame *frame, jsbytecode *pc);
 bool InterpretResume(JSContext *cx, HandleObject obj, HandleValue val, HandlePropertyName kind,
                      MutableHandleValue rval);
+bool DebugAfterYield(JSContext *cx, BaselineFrame *frame);
 
 bool StrictEvalPrologue(JSContext *cx, BaselineFrame *frame);
 bool HeavyweightFunPrologue(JSContext *cx, BaselineFrame *frame);

js/src/vm/Interpreter.cpp

@@ -1645,7 +1645,6 @@ CASE(JSOP_UNUSED190)
 CASE(JSOP_UNUSED191)
 CASE(JSOP_UNUSED192)
 CASE(JSOP_UNUSED196)
-CASE(JSOP_UNUSED208)
 CASE(JSOP_UNUSED209)
 CASE(JSOP_UNUSED210)
 CASE(JSOP_UNUSED211)
@@ -3413,6 +3412,14 @@ CASE(JSOP_RESUME)
     ADVANCE_AND_DISPATCH(0);
 }
 
+CASE(JSOP_DEBUGAFTERYIELD)
+{
+    // No-op in the interpreter, as GeneratorObject::resume takes care of
+    // fixing up InterpreterFrames.
+    MOZ_ASSERT_IF(REGS.fp()->script()->isDebuggee(), REGS.fp()->isDebuggee());
+}
+END_CASE(JSOP_DEBUGAFTERYIELD)
+
 CASE(JSOP_FINALYIELDRVAL)
 {
     RootedObject &gen = rootObject0;

js/src/vm/Opcodes.h

@@ -1619,7 +1619,15 @@
      */ \
     macro(JSOP_FORCEINTERPRETER, 207, "forceinterpreter", NULL,  1,  0,  0,  JOF_BYTE) \
     \
-    macro(JSOP_UNUSED208,     208, "unused208",    NULL,  1,  0,  0,  JOF_BYTE) \
+    /*
+     * Bytecode emitted after 'yield' statements to help the Debugger
+     * fix up the frame in the JITs. No-op in the interpreter.
+     *
+     *   Category: Debugger
+     *   Operands:
+     *   Stack: =>
+     */ \
+    macro(JSOP_DEBUGAFTERYIELD,  208, "debugafteryield",  NULL,  1,  0,  0,  JOF_BYTE) \
     macro(JSOP_UNUSED209,     209, "unused209",    NULL,  1,  0,  0,  JOF_BYTE) \
     macro(JSOP_UNUSED210,     210, "unused210",    NULL,  1,  0,  0,  JOF_BYTE) \
     macro(JSOP_UNUSED211,     211, "unused211",    NULL,  1,  0,  0,  JOF_BYTE) \

js/src/vm/Xdr.h

@@ -34,7 +34,7 @@ namespace js {
  * Nightly) and without (all others).  FIXME: Bug 1066322 - Enable ES6 symbols
  * in all builds.
  */
-static const uint32_t XDR_BYTECODE_VERSION_SUBTRAHEND = 202;
+static const uint32_t XDR_BYTECODE_VERSION_SUBTRAHEND = 204;
 static_assert(XDR_BYTECODE_VERSION_SUBTRAHEND % 2 == 0, "see the comment above");
 static const uint32_t XDR_BYTECODE_VERSION =
     uint32_t(0xb973c0de - (XDR_BYTECODE_VERSION_SUBTRAHEND