gistfile1.txt

# HG changeset patch
# Parent b857905d82b45456853866330c98b372b14f20db
# User Nicholas D. Matsakis <nmatsakis@mozilla.com>
Permit multiple ion compilation modes.  This implies the possibility of
multiple ion scripts per JSScript.
* * *
Add abstractions for cases that handle all comp. modes at once.
* * *
split out separate fields for seq, par
* * *
Convert Invalidate() to assert that it is being run in sequential mode.

diff --git a/js/src/ion/CodeGenerator.cpp b/js/src/ion/CodeGenerator.cpp
--- a/js/src/ion/CodeGenerator.cpp
+++ b/js/src/ion/CodeGenerator.cpp
@@ -8,16 +8,17 @@
 #include "CodeGenerator.h"
 #include "IonLinker.h"
 #include "IonSpewer.h"
 #include "MIRGenerator.h"
 #include "shared/CodeGenerator-shared-inl.h"
 #include "jsnum.h"
 #include "jsmath.h"
 #include "jsinterpinlines.h"
+#include "ExecutionModeInlines.h"
 
 #include "vm/StringObject-inl.h"
 
 using namespace js;
 using namespace js::ion;
 
 using mozilla::DebugOnly;
 
@@ -793,16 +794,27 @@ CodeGenerator::emitCallInvokeFunction(LI
     if (!callVM(InvokeFunctionInfo, call))
         return false;
 
     // Un-nestle %esp from the argument vector. No prefix was pushed.
     masm.reserveStack(unusedStack);
     return true;
 }
 
+static inline int32_t ionOffset(ExecutionMode executionMode)
+{
+    switch (executionMode) {
+      case SequentialExecution: return offsetof(JSScript, ion);
+      case ParallelExecution: return offsetof(JSScript, parallelIon);
+    }
+
+    JS_ASSERT(false);
+    return offsetof(JSScript, ion);
+}
+
 bool
 CodeGenerator::visitCallGeneric(LCallGeneric *call)
 {
     Register calleereg = ToRegister(call->getFunction());
     Register objreg    = ToRegister(call->getTempObject());
     Register nargsreg  = ToRegister(call->getNargsReg());
     uint32 unusedStack = StackOffsetOfPassedArg(call->argslot());
     Label invoke, thunk, makeCall, end;
@@ -826,17 +838,18 @@ CodeGenerator::visitCallGeneric(LCallGen
     if (!bailoutIf(Assembler::NotEqual, call->snapshot()))
         return false;
 
     // Guard that calleereg is a non-native function:
     masm.branchIfFunctionIsNative(calleereg, &invoke);
 
     // Knowing that calleereg is a non-native function, load the JSScript.
     masm.movePtr(Address(calleereg, offsetof(JSFunction, u.i.script_)), objreg);
-    masm.movePtr(Address(objreg, offsetof(JSScript, ion)), objreg);
+    ExecutionMode executionMode = gen->info().executionMode();
+    masm.movePtr(Address(objreg, ionOffset(executionMode)), objreg);
 
     // Guard that the IonScript has been compiled.
     masm.branchPtr(Assembler::BelowOrEqual, objreg, ImmWord(ION_COMPILING_SCRIPT), &invoke);
 
     // Nestle the StackPointer up to the argument vector.
     masm.freeStack(unusedStack);
 
     // Construct the IonFramePrefix.
@@ -884,48 +897,51 @@ CodeGenerator::visitCallGeneric(LCallGen
     masm.bind(&end);
     dropArguments(call->numStackArgs() + 1);
     return true;
 }
 
 bool
 CodeGenerator::visitCallKnown(LCallKnown *call)
 {
+    JSContext *cx = GetIonContext()->cx;
     Register calleereg = ToRegister(call->getFunction());
     Register objreg    = ToRegister(call->getTempObject());
     uint32 unusedStack = StackOffsetOfPassedArg(call->argslot());
     JSFunction *target = call->getSingleTarget();
     Label end, invoke;
 
     // Native single targets are handled by LCallNative.
     JS_ASSERT(!target->isNative());
     // Missing arguments must have been explicitly appended by the IonBuilder.
     JS_ASSERT(target->nargs <= call->numStackArgs());
 
     masm.checkStackAlignment();
 
     // If the function is known to be uncompilable, only emit the call to InvokeFunction.
-    if (target->script()->ion == ION_DISABLED_SCRIPT) {
+    ExecutionMode executionMode = gen->info().executionMode();
+    RootedScript targetScript(cx, target->script());
+    if (GetIonScript(targetScript, executionMode) == ION_DISABLED_SCRIPT) {
         if (!emitCallInvokeFunction(call, calleereg, call->numActualArgs(), unusedStack))
             return false;
 
         if (call->mir()->isConstructing()) {
             Label notPrimitive;
             masm.branchTestPrimitive(Assembler::NotEqual, JSReturnOperand, &notPrimitive);
             masm.loadValue(Address(StackPointer, unusedStack), JSReturnOperand);
             masm.bind(&notPrimitive);
         }
 
         dropArguments(call->numStackArgs() + 1);
         return true;
     }
 
     // Knowing that calleereg is a non-native function, load the JSScript.
     masm.movePtr(Address(calleereg, offsetof(JSFunction, u.i.script_)), objreg);
-    masm.movePtr(Address(objreg, offsetof(JSScript, ion)), objreg);
+    masm.movePtr(Address(objreg, ionOffset(executionMode)), objreg);
 
     // Guard that the IonScript has been compiled.
     masm.branchPtr(Assembler::BelowOrEqual, objreg, ImmWord(ION_COMPILING_SCRIPT), &invoke);
 
     // Load the start of the target IonCode.
     masm.movePtr(Address(objreg, IonScript::offsetOfMethod()), objreg);
     masm.movePtr(Address(objreg, IonCode::offsetOfCode()), objreg);
 
@@ -1083,16 +1099,18 @@ CodeGenerator::emitPopArguments(LApplyAr
 {
     // Pop |this| and Arguments.
     masm.freeStack(extraStackSpace);
 }
 
 bool
 CodeGenerator::visitApplyArgsGeneric(LApplyArgsGeneric *apply)
 {
+    JSContext *cx = GetIonContext()->cx;
+
     // Holds the function object.
     Register calleereg = ToRegister(apply->getFunction());
 
     // Temporary register for modifying the function object.
     Register objreg = ToRegister(apply->getTempObject());
     Register copyreg = ToRegister(apply->getTempCopy());
 
     // Holds the function nargs. Initially undefined.
@@ -1107,39 +1125,40 @@ CodeGenerator::visitApplyArgsGeneric(LAp
     }
 
     // Copy the arguments of the current function.
     emitPushArguments(apply, copyreg);
 
     masm.checkStackAlignment();
 
     // If the function is known to be uncompilable, only emit the call to InvokeFunction.
-    if (apply->hasSingleTarget() &&
-        (!apply->getSingleTarget()->isInterpreted() ||
-         apply->getSingleTarget()->script()->ion == ION_DISABLED_SCRIPT))
-    {
-        if (!emitCallInvokeFunction(apply, copyreg))
-            return false;
-        emitPopArguments(apply, copyreg);
-        return true;
+    ExecutionMode executionMode = gen->info().executionMode();
+    if (apply->hasSingleTarget()) {
+        RootedFunction target(cx, apply->getSingleTarget());
+        if (!CanIonCompile(cx, target, executionMode)) {
+            if (!emitCallInvokeFunction(apply, copyreg))
+                return false;
+            emitPopArguments(apply, copyreg);
+            return true;
+        }
     }
 
     Label end, invoke;
 
     // Guard that calleereg is a non-native function:
     if (!apply->hasSingleTarget()) {
         masm.branchIfFunctionIsNative(calleereg, &invoke);
     } else {
         // Native single targets are handled by LCallNative.
         JS_ASSERT(!apply->getSingleTarget()->isNative());
     }
 
     // Knowing that calleereg is a non-native function, load the JSScript.
     masm.movePtr(Address(calleereg, offsetof(JSFunction, u.i.script_)), objreg);
-    masm.movePtr(Address(objreg, offsetof(JSScript, ion)), objreg);
+    masm.movePtr(Address(objreg, ionOffset(executionMode)), objreg);
 
     // Guard that the IonScript has been compiled.
     masm.branchPtr(Assembler::BelowOrEqual, objreg, ImmWord(ION_COMPILING_SCRIPT), &invoke);
 
     // Call with an Ion frame or a rectifier frame.
     {
         // Create the frame descriptor.
         unsigned pushed = masm.framePushed();
@@ -2980,77 +2999,81 @@ CodeGenerator::generate()
     IonCode *code = linker.newCode(cx);
     if (!code)
         return false;
 
     // We encode safepoints after the OSI-point offsets have been determined.
     encodeSafepoints();
 
     RootedScript script(cx, gen->info().script());
-    JS_ASSERT(!script->hasIonScript());
+    ExecutionMode executionMode = gen->info().executionMode();
+    JS_ASSERT(!HasIonScript(script, executionMode));
 
     uint32 scriptFrameSize = frameClass_ == FrameSizeClass::None()
                            ? frameDepth_
                            : FrameSizeClass::FromDepth(frameDepth_).frameSize();
 
     // Check to make sure we didn't have a mid-build invalidation. If so, we
     // will trickle to ion::Compile() and return Method_Skipped.
     if (cx->compartment->types.compiledInfo.compilerOutput(cx)->isInvalidated())
         return true;
 
-    script->ion = IonScript::New(cx, slots, scriptFrameSize, snapshots_.size(),
-                                 bailouts_.length(), graph.numConstants(),
-                                 safepointIndices_.length(), osiIndices_.length(),
-                                 cacheList_.length(), barrierOffsets_.length(),
-                                 safepoints_.size(), graph.mir().numScripts());
-    if (!script->ion)
+    IonScript *ionScript =
+      IonScript::New(cx, slots, scriptFrameSize, snapshots_.size(),
+                     bailouts_.length(), graph.numConstants(),
+                     safepointIndices_.length(), osiIndices_.length(),
+                     cacheList_.length(), barrierOffsets_.length(),
+                     safepoints_.size(), graph.mir().numScripts());
+    SetIonScript(script, executionMode, ionScript);
+
+    if (!ionScript)
         return false;
     invalidateEpilogueData_.fixup(&masm);
     Assembler::patchDataWithValueCheck(CodeLocationLabel(code, invalidateEpilogueData_),
-                                       ImmWord(uintptr_t(script->ion)),
+                                       ImmWord(uintptr_t(ionScript)),
                                        ImmWord(uintptr_t(-1)));
 
     IonSpew(IonSpew_Codegen, "Created IonScript %p (raw %p)",
-            (void *) script->ion, (void *) code->raw());
-
-    script->ion->setInvalidationEpilogueDataOffset(invalidateEpilogueData_.offset());
-    script->ion->setOsrPc(gen->info().osrPc());
-    script->ion->setOsrEntryOffset(getOsrEntryOffset());
+            (void *) ionScript, (void *) code->raw());
+
+    ionScript->setInvalidationEpilogueDataOffset(invalidateEpilogueData_.offset());
+    ionScript->setOsrPc(gen->info().osrPc());
+    ionScript->setOsrEntryOffset(getOsrEntryOffset());
     ptrdiff_t real_invalidate = masm.actualOffset(invalidate_.offset());
-    script->ion->setInvalidationEpilogueOffset(real_invalidate);
-
-    script->ion->setMethod(code);
-    script->ion->setDeoptTable(deoptTable_);
+    ionScript->setInvalidationEpilogueOffset(real_invalidate);
+
+    ionScript->setMethod(code);
+    ionScript->setDeoptTable(deoptTable_);
     if (snapshots_.size())
-        script->ion->copySnapshots(&snapshots_);
+        ionScript->copySnapshots(&snapshots_);
     if (bailouts_.length())
-        script->ion->copyBailoutTable(&bailouts_[0]);
+        ionScript->copyBailoutTable(&bailouts_[0]);
     if (graph.numConstants())
-        script->ion->copyConstants(graph.constantPool());
+        ionScript->copyConstants(graph.constantPool());
     if (safepointIndices_.length())
-        script->ion->copySafepointIndices(&safepointIndices_[0], masm);
+        ionScript->copySafepointIndices(&safepointIndices_[0], masm);
     if (osiIndices_.length())
-        script->ion->copyOsiIndices(&osiIndices_[0], masm);
+        ionScript->copyOsiIndices(&osiIndices_[0], masm);
     if (cacheList_.length())
-        script->ion->copyCacheEntries(&cacheList_[0], masm);
+        ionScript->copyCacheEntries(&cacheList_[0], masm);
     if (barrierOffsets_.length())
-        script->ion->copyPrebarrierEntries(&barrierOffsets_[0], masm);
+        ionScript->copyPrebarrierEntries(&barrierOffsets_[0], masm);
     if (safepoints_.size())
-        script->ion->copySafepoints(&safepoints_);
+        ionScript->copySafepoints(&safepoints_);
 
     JS_ASSERT(graph.mir().numScripts() > 0);
-    script->ion->copyScriptEntries(graph.mir().scripts());
+    ionScript->copyScriptEntries(graph.mir().scripts());
 
     linkAbsoluteLabels();
 
     // The correct state for prebarriers is unknown until the end of compilation,
     // since a GC can occur during code generation. All barriers are emitted
     // off-by-default, and are toggled on here if necessary.
     if (cx->compartment->needsBarrier())
-        script->ion->toggleBarriers(true);
+        ionScript->toggleBarriers(true);
 
     return true;
 }
 
 // An out-of-line path to convert a boxed int32 to a double.
 class OutOfLineUnboxDouble : public OutOfLineCodeBase<CodeGenerator>
 {
     LUnboxDouble *unboxDouble_;
diff --git a/js/src/ion/CompileInfo.h b/js/src/ion/CompileInfo.h
--- a/js/src/ion/CompileInfo.h
+++ b/js/src/ion/CompileInfo.h
@@ -12,22 +12,33 @@ namespace js {
 namespace ion {
 
 inline unsigned
 CountArgSlots(JSFunction *fun)
 {
     return fun ? fun->nargs + 2 : 1; // +2 for |scopeChain| and |this|, or +1 for |scopeChain|
 }
 
+enum ExecutionMode {
+    // Normal JavaScript execution
+    SequentialExecution,
+
+    // JavaScript code to be executed in parallel worker threads,
+    // e.g. by ParallelArray
+    ParallelExecution
+};
+
 // Contains information about the compilation source for IR being generated.
 class CompileInfo
 {
   public:
-    CompileInfo(JSScript *script, JSFunction *fun, jsbytecode *osrPc, bool constructing)
-      : script_(script), fun_(fun), osrPc_(osrPc), constructing_(constructing)
+    CompileInfo(JSScript *script, JSFunction *fun, jsbytecode *osrPc, bool constructing,
+                ExecutionMode executionMode)
+      : script_(script), fun_(fun), osrPc_(osrPc), constructing_(constructing),
+        executionMode_(executionMode)
     {
         JS_ASSERT_IF(osrPc, JSOp(*osrPc) == JSOP_LOOPENTRY);
         nslots_ = script->nslots + CountArgSlots(fun);
     }
 
     JSScript *script() const {
         return script_;
     }
@@ -128,20 +139,29 @@ class CompileInfo
     uint32 stackSlot(uint32 i) const {
         return firstStackSlot() + i;
     }
 
     bool hasArguments() {
         return script()->argumentsHasVarBinding();
     }
 
+    ExecutionMode executionMode() const {
+        return executionMode_;
+    }
+
+    bool isParallelExecution() const {
+        return executionMode_ == ParallelExecution;
+    }
+
   private:
     JSScript *script_;
     JSFunction *fun_;
     unsigned nslots_;
     jsbytecode *osrPc_;
     bool constructing_;
+    ExecutionMode executionMode_;
 };
 
 } // namespace ion
 } // namespace js
 
 #endif
diff --git a/js/src/ion/ExecutionModeInlines.h b/js/src/ion/ExecutionModeInlines.h
new file mode 100644
--- /dev/null
+++ b/js/src/ion/ExecutionModeInlines.h
@@ -0,0 +1,103 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=4 sw=4 et tw=99:
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jsion_compilemode_h__
+#define jsion_compilemode_h__
+
+namespace js {
+namespace ion {
+
+static inline bool HasIonScript(JSScript *script, ExecutionMode cmode)
+{
+    switch (cmode) {
+      case SequentialExecution: return script->hasIonScript();
+      case ParallelExecution: return script->hasParallelIonScript();
+    }
+    JS_NOT_REACHED("No such execution mode");
+    return false;
+}
+
+static inline IonScript *GetIonScript(JSScript *script, ExecutionMode cmode)
+{
+    switch (cmode) {
+      case SequentialExecution: return script->ion;
+      case ParallelExecution: return script->parallelIon;
+    }
+    JS_NOT_REACHED("No such execution mode");
+    return NULL;
+}
+
+static inline void SetIonScript(JSScript *script, ExecutionMode cmode, IonScript *ionScript)
+{
+    switch (cmode) {
+      case SequentialExecution: script->ion = ionScript; return;
+      case ParallelExecution: script->parallelIon = ionScript; return;
+    }
+    JS_NOT_REACHED("No such execution mode");
+}
+
+static inline bool CanIonCompile(HandleScript script, ExecutionMode cmode)
+{
+    switch (cmode) {
+      case SequentialExecution: return script->canIonCompile();
+      case ParallelExecution: return script->canParallelIonCompile();
+    }
+    JS_NOT_REACHED("No such execution mode");
+    return false;
+}
+
+static inline bool CanIonCompile(JSContext *cx, HandleFunction fun, ExecutionMode cmode)
+{
+    if (!fun->isInterpreted())
+        return false;
+    RootedScript script(cx, fun->script());
+    return CanIonCompile(script, cmode);
+}
+
+static inline bool CompilingOffThread(JSScript *script, ExecutionMode cmode)
+{
+    switch (cmode) {
+      case SequentialExecution: return script->isIonCompilingOffThread();
+      case ParallelExecution: return script->isParallelIonCompilingOffThread();
+    }
+    JS_NOT_REACHED("No such execution mode");
+    return false;
+}
+
+static inline bool CompilingOffThread(HandleScript script, ExecutionMode cmode)
+{
+    switch (cmode) {
+      case SequentialExecution: return script->isIonCompilingOffThread();
+      case ParallelExecution: return script->isParallelIonCompilingOffThread();
+    }
+    JS_NOT_REACHED("No such execution mode");
+    return false;
+}
+
+static inline bool Disabled(JSScript *script, ExecutionMode cmode) {
+    switch (cmode) {
+      case SequentialExecution: return script->isIonCompilingOffThread();
+      case ParallelExecution: return script->isParallelIonCompilingOffThread();
+    }
+    JS_NOT_REACHED("No such execution mode");
+    return false;
+}
+
+static inline types::CompilerOutput::Kind CompilerOutputKind(ExecutionMode cmode)
+{
+    switch (cmode) {
+      case SequentialExecution: return types::CompilerOutput::Ion;
+      case ParallelExecution: return types::CompilerOutput::ParallelIon;
+    }
+    JS_NOT_REACHED("No such execution mode");
+    return types::CompilerOutput::Ion;
+}
+
+}
+}
+
+#endif
diff --git a/js/src/ion/Ion.cpp b/js/src/ion/Ion.cpp
--- a/js/src/ion/Ion.cpp
+++ b/js/src/ion/Ion.cpp
@@ -32,16 +32,17 @@
 #include "gc/Marking.h"
 #include "jsgcinlines.h"
 #include "jsinferinlines.h"
 #include "jsobjinlines.h"
 #include "vm/Stack-inl.h"
 #include "ion/IonFrames-inl.h"
 #include "ion/CompilerRoot.h"
 #include "methodjit/Retcon.h"
+#include "ExecutionModeInlines.h"
 
 #if JS_TRACE_LOGGING
 #include "TraceLogging.h"
 #endif
 
 using namespace js;
 using namespace js::ion;
 
@@ -958,16 +959,26 @@ class AutoDestroyAllocator
 
     ~AutoDestroyAllocator()
     {
         if (alloc)
             js_delete(alloc);
     }
 };
 
+class SequentialCompileContext {
+public:
+    ExecutionMode executionMode() {
+        return SequentialExecution;
+    }
+
+    bool compile(IonBuilder *builder, MIRGraph *graph,
+                 AutoDestroyAllocator &autoDestroy);
+};
+
 void
 AttachFinishedCompilations(JSContext *cx)
 {
 #ifdef JS_THREADSAFE
     AssertCanGC();
     IonCompartment *ion = cx->compartment->ionCompartment();
     if (!ion || !cx->runtime->workerThreadState)
         return;
@@ -983,17 +994,18 @@ AttachFinishedCompilations(JSContext *cx
         IonBuilder *builder = compilations.popCopy();
 
         if (builder->backgroundCompiledLir) {
             RootedScript script(cx, builder->script());
             IonContext ictx(cx, cx->compartment, &builder->temp());
 
             CodeGenerator codegen(builder, *builder->backgroundCompiledLir);
 
-            types::AutoEnterCompilation enterCompiler(cx, types::AutoEnterCompilation::Ion);
+            ExecutionMode executionMode = builder->info().executionMode();
+            types::AutoEnterCompilation enterCompiler(cx, CompilerOutputKind(executionMode));
             enterCompiler.initExisting(builder->recompileInfo);
 
             bool success;
             {
                 // Release the worker thread lock and root the compiler for GC.
                 AutoTempAllocatorRooter root(cx, &builder->temp());
                 AutoUnlockWorkerThreadState unlock(cx->runtime);
                 success = codegen.generate();
@@ -1013,18 +1025,20 @@ AttachFinishedCompilations(JSContext *cx
     }
 
     compilations.clear();
 #endif
 }
 
 static const size_t BUILDER_LIFO_ALLOC_PRIMARY_CHUNK_SIZE = 1 << 12;
 
+template <typename CompileContext>
 static bool
-IonCompile(JSContext *cx, JSScript *script, JSFunction *fun, jsbytecode *osrPc, bool constructing)
+IonCompile(JSContext *cx, JSScript *script, JSFunction *fun, jsbytecode *osrPc, bool constructing,
+           CompileContext &compileContext)
 {
     AssertCanGC();
 #if JS_TRACE_LOGGING
     AutoTraceLog logger(TraceLogging::defaultLogger(),
                         TraceLogging::ION_COMPILE_START,
                         TraceLogging::ION_COMPILE_STOP,
                         script);
 #endif
@@ -1040,35 +1054,50 @@ IonCompile(JSContext *cx, JSScript *scri
         return false;
 
     IonContext ictx(cx, cx->compartment, temp);
 
     if (!cx->compartment->ensureIonCompartmentExists(cx))
         return false;
 
     MIRGraph *graph = alloc->new_<MIRGraph>(temp);
-    CompileInfo *info = alloc->new_<CompileInfo>(script, fun, osrPc, constructing);
+    ExecutionMode executionMode = compileContext.executionMode();
+    CompileInfo *info = alloc->new_<CompileInfo>(script, fun, osrPc, constructing,
+                                                 executionMode);
     if (!info)
         return false;
 
     types::AutoEnterTypeInference enter(cx, true);
     TypeInferenceOracle oracle;
 
     if (!oracle.init(cx, script))
         return false;
 
     AutoFlushCache afc("IonCompile");
 
-    types::AutoEnterCompilation enterCompiler(cx, types::AutoEnterCompilation::Ion);
+    types::AutoEnterCompilation enterCompiler(cx, CompilerOutputKind(executionMode));
     enterCompiler.init(script, false, 0);
 
     AutoTempAllocatorRooter root(cx, temp);
 
     IonBuilder *builder = alloc->new_<IonBuilder>(cx, temp, graph, &oracle, info);
+    if (!compileContext.compile(builder, graph, autoDestroy)) {
+        IonSpew(IonSpew_Abort, "IM Compilation failed.");
+        return false;
+    }
+
+    return true;
+}
+
+bool
+SequentialCompileContext::compile(IonBuilder *builder, MIRGraph *graph,
+                                  AutoDestroyAllocator &autoDestroy)
+{
     JS_ASSERT(!builder->script()->ion);
+    JSContext *cx = GetIonContext()->cx;
 
     IonSpewNewFunction(graph, builder->script().unsafeGet());
 
     if (!builder->build()) {
         IonSpew(IonSpew_Abort, "Builder failed to build.");
         return false;
     }
     builder->clearForBackEnd();
@@ -1103,17 +1132,18 @@ IonCompile(JSContext *cx, JSScript *scri
     IonSpewEndFunction();
 
     return true;
 }
 
 bool
 TestIonCompile(JSContext *cx, JSScript *script, JSFunction *fun, jsbytecode *osrPc, bool constructing)
 {
-    if (!IonCompile(cx, script, fun, osrPc, constructing)) {
+    SequentialCompileContext compileContext;
+    if (!IonCompile(cx, script, fun, osrPc, constructing, compileContext)) {
         if (!cx->isExceptionPending())
             ForbidCompilation(cx, script);
         return false;
     }
     return true;
 }
 
 static bool
@@ -1223,17 +1253,18 @@ Compile(JSContext *cx, JSScript *script,
         // bumping the use count twice.
         if (script->getUseCount() < js_IonOptions.usesBeforeCompile)
             return Method_Skipped;
     } else {
         if (script->incUseCount() < js_IonOptions.usesBeforeCompileNoJaeger)
             return Method_Skipped;
     }
 
-    if (!IonCompile(cx, script, fun, osrPc, constructing))
+    SequentialCompileContext compileContext;
+    if (!IonCompile(cx, script, fun, osrPc, constructing, compileContext))
         return Method_CantCompile;
 
     // Compilation succeeded, but we invalidated right away.
     return script->hasIonScript() ? Method_Compiled : Method_Skipped;
 }
 
 } // namespace ion
 } // namespace js
@@ -1719,17 +1750,21 @@ ion::Invalidate(types::TypeCompartment &
     IonSpew(IonSpew_Invalidate, "Start invalidation.");
     AutoFlushCache afc ("Invalidate");
 
     // Add an invalidation reference to all invalidated IonScripts to indicate
     // to the traversal which frames have been invalidated.
     bool anyInvalidation = false;
     for (size_t i = 0; i < invalid.length(); i++) {
         const types::CompilerOutput &co = *invalid[i].compilerOutput(types);
-        if (co.isIon()) {
+        switch (co.kind()) {
+          case types::CompilerOutput::MethodJIT:
+            break;
+          case types::CompilerOutput::Ion:
+          case types::CompilerOutput::ParallelIon:
             JS_ASSERT(co.isValid());
             IonSpew(IonSpew_Invalidate, " Invalidate %s:%u, IonScript %p",
                     co.script->filename, co.script->lineno, co.ion());
 
             // Keep the ion script alive during the invalidation and flag this
             // ionScript as being invalidated.  This increment is removed by the
             // loop after the calls to InvalidateActivation.
             co.ion()->incref();
@@ -1745,39 +1780,48 @@ ion::Invalidate(types::TypeCompartment &
     for (IonActivationIterator iter(fop->runtime()); iter.more(); ++iter)
         InvalidateActivation(fop, iter.top(), false);
 
     // Drop the references added above. If a script was never active, its
     // IonScript will be immediately destroyed. Otherwise, it will be held live
     // until its last invalidated frame is destroyed.
     for (size_t i = 0; i < invalid.length(); i++) {
         types::CompilerOutput &co = *invalid[i].compilerOutput(types);
-        if (co.isIon()) {
-            JS_ASSERT(co.isValid());
-            JSScript *script = co.script;
-            IonScript *ionScript = script->ionScript();
+        ExecutionMode executionMode;
+        switch (co.kind()) {
+          case types::CompilerOutput::MethodJIT:
+            continue;
+          case types::CompilerOutput::Ion:
+            executionMode = SequentialExecution;
+            break;
+          case types::CompilerOutput::ParallelIon:
+            executionMode = ParallelExecution;
+            break;
+        }
+        JS_ASSERT(co.isValid());
+        JSScript *script = co.script;
+        IonScript *ionScript = GetIonScript(script, executionMode);
 
-            JSCompartment *compartment = script->compartment();
-            if (compartment->needsBarrier()) {
-                // We're about to remove edges from the JSScript to gcthings
-                // embedded in the IonScript. Perform one final trace of the
-                // IonScript for the incremental GC, as it must know about
-                // those edges.
-                IonScript::Trace(compartment->barrierTracer(), ionScript);
-            }
+        JSCompartment *compartment = script->compartment();
+        if (compartment->needsBarrier()) {
+            // We're about to remove edges from the JSScript to gcthings
+            // embedded in the IonScript. Perform one final trace of the
+            // IonScript for the incremental GC, as it must know about
+            // those edges.
+            IonScript::Trace(compartment->barrierTracer(), ionScript);
+        }
 
-            ionScript->decref(fop);
-            script->ion = NULL;
-            co.invalidate();
+        ionScript->decref(fop);
+        SetIonScript(script, executionMode, NULL);
+        co.invalidate();
 
-            // Wait for the scripts to get warm again before doing another
-            // compile, unless we are recompiling *because* a script got hot.
-            if (resetUses)
-                script->resetUseCount();
-        }
+        // Wait for the scripts to get warm again before doing another
+        // compile, unless we are recompiling *because* a script got hot.
+        if (resetUses)
+            script->resetUseCount();
     }
 }
 
 void
 ion::Invalidate(JSContext *cx, const Vector<types::RecompileInfo> &invalid, bool resetUses)
 {
     ion::Invalidate(cx->compartment->types, cx->runtime->defaultFreeOp(), invalid, resetUses);
 }
@@ -1886,8 +1930,47 @@ AutoFlushCache::AutoFlushCache(const cha
         comp->setFlusher(this);
     } else {
         IonSpew(IonSpew_CacheFlush, "<%s DEAD>\n", nonce);
     }
     myCompartment_ = comp;
 }
 int js::ion::LabelBase::id_count = 0;
 
+void
+ion::PurgeCaches(JSScript *script, JSCompartment *c) {
+    if (script->hasIonScript())
+        script->ion->purgeCaches(c);
+
+    if (script->hasParallelIonScript())
+        script->ion->purgeCaches(c);
+}
+
+size_t
+ion::MemoryUsed(JSScript *script, JSMallocSizeOfFun mallocSizeOf) {
+    size_t result = 0;
+
+    if (script->hasIonScript())
+        result += script->ion->sizeOfIncludingThis(mallocSizeOf);
+
+    if (script->hasParallelIonScript())
+        result += script->parallelIon->sizeOfIncludingThis(mallocSizeOf);
+
+    return result;
+}
+
+void
+ion::DestroyIonScripts(FreeOp *fop, JSScript *script) {
+    if (script->hasIonScript())
+        ion::IonScript::Destroy(fop, script->ion);
+
+    if (script->hasParallelIonScript())
+        ion::IonScript::Destroy(fop, script->parallelIon);
+}
+
+void
+ion::TraceIonScripts(JSTracer* trc, JSScript *script) {
+    if (script->hasIonScript())
+        ion::IonScript::Trace(trc, script->ion);
+
+    if (script->hasParallelIonScript())
+        ion::IonScript::Trace(trc, script->parallelIon);
+}
diff --git a/js/src/ion/Ion.h b/js/src/ion/Ion.h
--- a/js/src/ion/Ion.h
+++ b/js/src/ion/Ion.h
@@ -263,13 +263,18 @@ bool TestIonCompile(JSContext *cx, JSScr
 static inline bool IsEnabled(JSContext *cx)
 {
     return cx->hasRunOption(JSOPTION_ION) && cx->typeInferenceEnabled();
 }
 
 void ForbidCompilation(JSContext *cx, JSScript *script);
 uint32_t UsesBeforeIonRecompile(JSScript *script, jsbytecode *pc);
 
+void PurgeCaches(JSScript *script, JSCompartment *c);
+size_t MemoryUsed(JSScript *script, JSMallocSizeOfFun mallocSizeOf);
+void DestroyIonScripts(FreeOp *fop, JSScript *script);
+void TraceIonScripts(JSTracer* trc, JSScript *script);
+
 } // namespace ion
 } // namespace js
 
 #endif // jsion_ion_h__
 
diff --git a/js/src/ion/IonBuilder.cpp b/js/src/ion/IonBuilder.cpp
--- a/js/src/ion/IonBuilder.cpp
+++ b/js/src/ion/IonBuilder.cpp
@@ -10,16 +10,17 @@
 #include "MIRGraph.h"
 #include "Ion.h"
 #include "IonAnalysis.h"
 #include "IonSpewer.h"
 #include "frontend/BytecodeEmitter.h"
 
 #include "jsscriptinlines.h"
 #include "jstypedarrayinlines.h"
+#include "ExecutionModeInlines.h"
 
 #ifdef JS_THREADSAFE
 # include "prthread.h"
 #endif
 
 using namespace js;
 using namespace js::ion;
 
@@ -199,18 +200,18 @@ IonBuilder::canInlineTarget(JSFunction *
     }
 
     if (target->getParent() != &script_->global()) {
         IonSpew(IonSpew_Inlining, "Cannot inline due to scope mismatch");
         return false;
     }
 
     RootedScript inlineScript(cx, target->script());
-
-    if (!inlineScript->canIonCompile()) {
+    ExecutionMode executionMode = info().executionMode();
+    if (!CanIonCompile(inlineScript, executionMode)) {
         IonSpew(IonSpew_Inlining, "Cannot inline due to disable Ion compilation");
         return false;
     }
 
     // Allow inlining of recursive calls, but only one level deep.
     IonBuilder *builder = callerBuilder_;
     while (builder) {
         if (builder->script() == inlineScript) {
@@ -2824,17 +2825,18 @@ IonBuilder::jsop_call_inline(HandleFunct
         return false;
     for (int32 i = argc; i >= 0; i--)
         argv[i] = current->pop();
 
     // Compilation information is allocated for the duration of the current tempLifoAlloc
     // lifetime.
     RootedScript calleeScript(cx, callee->script());
     CompileInfo *info = cx->tempLifoAlloc().new_<CompileInfo>(calleeScript.get(), callee,
-                                                              (jsbytecode *)NULL, constructing);
+                                                              (jsbytecode *)NULL, constructing,
+                                                              SequentialExecution);
     if (!info)
         return false;
 
     MIRGraphExits saveExits;
     AutoAccumulateExits aae(graph(), saveExits);
 
     TypeInferenceOracle oracle;
     if (!oracle.init(cx, calleeScript))
diff --git a/js/src/jsdbgapi.cpp b/js/src/jsdbgapi.cpp
--- a/js/src/jsdbgapi.cpp
+++ b/js/src/jsdbgapi.cpp
@@ -547,18 +547,19 @@ JS_SetTopFrameAnnotation(JSContext *cx, 
     // because we will never EnterIon on a frame with an annotation.
     fp->setAnnotation(annotation);
 
     RawScript script = fp->script().get(nogc);
 
     ReleaseAllJITCode(cx->runtime->defaultFreeOp());
 
     // Ensure that we'll never try to compile this again.
-    JS_ASSERT(!script->hasIonScript());
+    JS_ASSERT(!script->hasAnyIonScript());
     script->ion = ION_DISABLED_SCRIPT;
+    script->parallelIon = ION_DISABLED_SCRIPT;
 }
 
 JS_PUBLIC_API(JSObject *)
 JS_GetFrameScopeChain(JSContext *cx, JSStackFrame *fpArg)
 {
     StackFrame *fp = Valueify(fpArg);
     JS_ASSERT(cx->stack.space().containsSlow(fp));
     AutoCompartment ac(cx, fp->scopeChain());
diff --git a/js/src/jsfun.cpp b/js/src/jsfun.cpp
--- a/js/src/jsfun.cpp
+++ b/js/src/jsfun.cpp
@@ -127,17 +127,17 @@ fun_getProperty(JSContext *cx, HandleObj
 #ifdef JS_ION
         AutoAssertNoGC nogc;
 
         // If this script hasn't been compiled yet, make sure it will never
         // be compiled. IonMonkey does not guarantee |f.arguments| can be
         // fully recovered, so we try to mitigate observing this behavior by
         // detecting its use early.
         RawScript script = iter.script().get(nogc);
-        if (!script->hasIonScript())
+        if (!script->hasAnyIonScript())
             ion::ForbidCompilation(cx, script);
 #endif
 
         vp.setObject(*argsobj);
         return true;
     }
 
 #ifdef JS_METHODJIT
diff --git a/js/src/jsgc.cpp b/js/src/jsgc.cpp
--- a/js/src/jsgc.cpp
+++ b/js/src/jsgc.cpp
@@ -5870,18 +5870,17 @@ PurgeJITCaches(JSCompartment *c)
         JSScript *script = i.get<JSScript>();
 
         /* Discard JM caches. */
         mjit::PurgeCaches(script);
 
 #ifdef JS_ION
 
         /* Discard Ion caches. */
-        if (script->hasIonScript())
-            script->ion->purgeCaches(c);
+        ion::PurgeCaches(script, c);
 
 #endif
     }
 #endif
 }
 
 AutoTransplantGC::AutoTransplantGC(JSContext *cx)
   : runtime(cx->runtime),
diff --git a/js/src/jsinfer.cpp b/js/src/jsinfer.cpp
--- a/js/src/jsinfer.cpp
+++ b/js/src/jsinfer.cpp
@@ -1992,17 +1992,17 @@ JITCodeHasCheck(HandleScript script, jsb
                     found = true;
             }
             if (!found)
                 return false;
         }
     }
 #endif
 
-    if (script->hasIonScript())
+    if (script->hasAnyIonScript())
         return false;
 
     return true;
 }
 
 /*
  * Force recompilation of any jitcode for script at pc, or of any other script
  * which this script was inlined into.
@@ -2021,18 +2021,24 @@ AddPendingRecompile(JSContext *cx, Handl
     /*
      * Remind Ion not to save the compile code if generating type
      * inference information mid-compilation causes an invalidation of the
      * script being compiled.
      */
     RecompileInfo& info = cx->compartment->types.compiledInfo;
     if (info.outputIndex != RecompileInfo::NoCompilerRunning) {
         CompilerOutput *co = info.compilerOutput(cx);
-        if (co->isIon() && co->script == script) {
-            co->invalidate();
+        switch (co->kind()) {
+          case CompilerOutput::MethodJIT:
+            break;
+          case CompilerOutput::Ion:
+          case CompilerOutput::ParallelIon:
+            if (co->script == script)
+                co->invalidate();
+            break;
         }
     }
 
     /*
      * When one script is inlined into another the caller listens to state
      * changes on the callee's script, so trigger these to force recompilation
      * of any such callers.
      */
@@ -2412,21 +2418,26 @@ TypeCompartment::processPendingRecompile
     JS_ASSERT(!pending->empty());
 
 #ifdef JS_METHODJIT
 
     mjit::ExpandInlineFrames(compartment());
 
     for (unsigned i = 0; i < pending->length(); i++) {
         CompilerOutput &co = *(*pending)[i].compilerOutput(*this);
-        if (co.isJM()) {
+        switch (co.kind()) {
+          case CompilerOutput::MethodJIT:
             JS_ASSERT(co.isValid());
             mjit::Recompiler::clearStackReferences(fop, co.script);
             co.mjit()->destroyChunk(fop, co.chunkIndex);
             JS_ASSERT(co.script == NULL);
+            break;
+          case CompilerOutput::Ion:
+          case CompilerOutput::ParallelIon:
+            break;
         }
     }
 
 # ifdef JS_ION
     ion::Invalidate(*this, fop, *pending);
 # endif
 #endif /* JS_METHODJIT */
 
@@ -2513,17 +2524,17 @@ TypeCompartment::addPendingRecompile(JSC
         return;
     }
 
 #ifdef JS_METHODJIT
     mjit::JITScript *jit = co->script->getJIT(co->constructing, co->barriers);
     bool hasJITCode = jit && jit->chunkDescriptor(co->chunkIndex).chunk;
 
 # if defined(JS_ION)
-    hasJITCode |= !!co->script->hasIonScript();
+    hasJITCode |= !!co->script->hasAnyIonScript();
 # endif
 
     if (!hasJITCode) {
         /* Scripts which haven't been compiled yet don't need to be recompiled. */
         return;
     }
 #endif
 
@@ -2580,16 +2591,19 @@ TypeCompartment::addPendingRecompile(JSC
         }
     }
 
 # ifdef JS_ION
     CancelOffThreadIonCompile(cx->compartment, script);
 
     if (script->hasIonScript())
         addPendingRecompile(cx, script->ionScript()->recompileInfo());
+
+    if (script->hasParallelIonScript())
+        addPendingRecompile(cx, script->parallelIonScript()->recompileInfo());
 # endif
 #endif
 }
 
 void
 TypeCompartment::monitorBytecode(JSContext *cx, HandleScript script, uint32_t offset,
                                  bool returnOnly)
 {
diff --git a/js/src/jsinfer.h b/js/src/jsinfer.h
--- a/js/src/jsinfer.h
+++ b/js/src/jsinfer.h
@@ -1208,27 +1208,37 @@ typedef HashMap<AllocationSiteKey,ReadBa
 /*
  * Information about the result of the compilation of a script.  This structure
  * stored in the TypeCompartment is indexed by the RecompileInfo. This
  * indirection enable the invalidation of all constraints related to the same
  * compilation. The compiler output is build by the AutoEnterCompilation.
  */
 struct CompilerOutput
 {
+    enum Kind {
+        MethodJIT,
+        Ion,
+        ParallelIon
+    };
+
     JSScript *script;
-    bool isIonFlag : 1;
+
+    // This integer will always be a member of CompilerOutput::Kind,
+    // but, for portability, bitfields are limited to bool, int, and
+    // unsigned int.  You should really use the accessor below.
+    unsigned kindInt : 2;
     bool constructing : 1;
     bool barriers : 1;
     bool pendingRecompilation : 1;
-    uint32_t chunkIndex:28;
+    uint32_t chunkIndex:27;
 
     CompilerOutput();
 
-    bool isJM() const { return !isIonFlag; }
-    bool isIon() const { return isIonFlag; }
+    Kind kind() const { return static_cast<Kind>(kindInt); }
+    void setKind(Kind k) { kindInt = k; }
 
     mjit::JITScript *mjit() const;
     ion::IonScript *ion() const;
 
     bool isValid() const;
 
     void setPendingRecompilation() {
         pendingRecompilation = true;
diff --git a/js/src/jsinferinlines.h b/js/src/jsinferinlines.h
--- a/js/src/jsinferinlines.h
+++ b/js/src/jsinferinlines.h
@@ -83,79 +83,95 @@ namespace types {
 
 /////////////////////////////////////////////////////////////////////
 // CompilerOutput & RecompileInfo
 /////////////////////////////////////////////////////////////////////
 
 inline
 CompilerOutput::CompilerOutput()
   : script(NULL),
-    isIonFlag(false),
+    kindInt(MethodJIT),
     constructing(false),
     barriers(false),
     chunkIndex(false)
 {
 }
 
 inline mjit::JITScript *
 CompilerOutput::mjit() const
 {
 #ifdef JS_METHODJIT
-    JS_ASSERT(isJM() && isValid());
+    JS_ASSERT(kind() == MethodJIT && isValid());
     return script->getJIT(constructing, barriers);
 #else
     return NULL;
 #endif
 }
 
 inline ion::IonScript *
 CompilerOutput::ion() const
 {
 #ifdef JS_ION
-    JS_ASSERT(isIon() && isValid());
-    return script->ionScript();
-#else
+    JS_ASSERT(kind() != MethodJIT && isValid());
+    switch (kind()) {
+      case MethodJIT: break;
+      case Ion: return script->ionScript();
+      case ParallelIon: return script->parallelIonScript();
+    }
+#endif
+    JS_NOT_REACHED("Invalid kind of CompilerOutput");
     return NULL;
-#endif
 }
 
 inline bool
 CompilerOutput::isValid() const
 {
     if (!script)
         return false;
 
 #if defined(DEBUG) && (defined(JS_METHODJIT) || defined(JS_ION))
     TypeCompartment &types = script->compartment()->types;
 #endif
 
+    switch (kind()) {
+      case MethodJIT: {
 #ifdef JS_METHODJIT
-    if (isJM()) {
         mjit::JITScript *jit = script->getJIT(constructing, barriers);
         if (!jit)
             return false;
         mjit::JITChunk *chunk = jit->chunkDescriptor(chunkIndex).chunk;
         if (!chunk)
             return false;
         JS_ASSERT(this == chunk->recompileInfo.compilerOutput(types));
         return true;
-    }
 #endif
+      }
 
+      case Ion:
 #ifdef JS_ION
-    if (isIon()) {
         if (script->hasIonScript()) {
             JS_ASSERT(this == script->ion->recompileInfo().compilerOutput(types));
             return true;
         }
         if (script->isIonCompilingOffThread())
             return true;
+#endif
+        return false;
+
+      case ParallelIon:
+#ifdef JS_ION
+        if (script->hasParallelIonScript()) {
+            JS_ASSERT(this == script->parallelIonScript()->recompileInfo().compilerOutput(types));
+            return true;
+        }
+        if (script->isParallelIonCompilingOffThread())
+            return true;
+#endif
         return false;
     }
-#endif
     return false;
 }
 
 inline CompilerOutput*
 RecompileInfo::compilerOutput(TypeCompartment &types) const
 {
     return &(*types.constrainedOutputs)[outputIndex];
 }
@@ -382,37 +398,32 @@ struct AutoEnterTypeInference
 /*
  * Structure marking the currently compiled script, for constraints which can
  * trigger recompilation.
  */
 struct AutoEnterCompilation
 {
     JSContext *cx;
     RecompileInfo &info;
+    CompilerOutput::Kind kind;
 
-    enum Compiler {
-        JM,
-        Ion
-    };
-    Compiler mode;
-
-    AutoEnterCompilation(JSContext *cx, Compiler mode)
+    AutoEnterCompilation(JSContext *cx, CompilerOutput::Kind kind)
       : cx(cx),
         info(cx->compartment->types.compiledInfo),
-        mode(mode)
+        kind(kind)
     {
         JS_ASSERT(cx->compartment->activeAnalysis);
         JS_ASSERT(info.outputIndex == RecompileInfo::NoCompilerRunning);
     }
 
     bool init(JSScript *script, bool constructing, unsigned chunkIndex)
     {
         CompilerOutput co;
         co.script = script;
-        co.isIonFlag = (mode == Ion);
+        co.setKind(kind);
         co.constructing = constructing;
         co.barriers = cx->compartment->compileBarriers();
         co.chunkIndex = chunkIndex;
 
         // This flag is used to prevent adding the current compiled script in
         // the list of compiler output which should be invalided.  This is
         // necessary because we can run some analysis might discard the script
         // it-self, which can happen when the monitored value does not reflect
diff --git a/js/src/jsinterpinlines.h b/js/src/jsinterpinlines.h
--- a/js/src/jsinterpinlines.h
+++ b/js/src/jsinterpinlines.h
@@ -1002,21 +1002,21 @@ class FastInvokeGuard
     RootedScript script_;
 #ifdef JS_ION
     ion::IonContext ictx_;
     bool useIon_;
 #endif
 
   public:
     FastInvokeGuard(JSContext *cx, const Value &fval)
-      : fun_(cx),
-        script_(cx)
+      : fun_(cx)
+      , script_(cx)
 #ifdef JS_ION
-        , ictx_(cx, cx->compartment, NULL),
-        useIon_(ion::IsEnabled(cx))
+      , ictx_(cx, cx->compartment, NULL)
+      , useIon_(ion::IsEnabled(cx))
 #endif
     {
         initFunction(fval);
     }
 
     void initFunction(const Value &fval) {
         if (fval.isObject() && fval.toObject().isFunction()) {
             JSFunction *fun = fval.toObject().toFunction();
diff --git a/js/src/jsmemorymetrics.cpp b/js/src/jsmemorymetrics.cpp
--- a/js/src/jsmemorymetrics.cpp
+++ b/js/src/jsmemorymetrics.cpp
@@ -15,16 +15,17 @@
 #include "jsgc.h"
 #include "jsobj.h"
 #include "jsscope.h"
 #include "jsscript.h"
 
 #include "jsobjinlines.h"
 
 #include "ion/IonCode.h"
+#include "ion/Ion.h"
 
 namespace js {
 
 size_t MemoryReportingSundriesThreshold()
 {
     return 8 * 1024;
 }
 
@@ -227,18 +228,17 @@ StatsCellCallback(JSRuntime *rt, void *d
     case JSTRACE_SCRIPT:
     {
         JSScript *script = static_cast<JSScript *>(thing);
         cStats->gcHeapScripts += thingSize;
         cStats->scriptData += script->sizeOfData(rtStats->mallocSizeOf);
 #ifdef JS_METHODJIT
         cStats->jaegerData += script->sizeOfJitScripts(rtStats->mallocSizeOf);
 # ifdef JS_ION
-        if (script->hasIonScript())
-            cStats->ionData += script->ion->sizeOfIncludingThis(rtStats->mallocSizeOf);
+        cStats->ionData += ion::MemoryUsed(script, rtStats->mallocSizeOf);
 # endif
 #endif
 
         ScriptSource *ss = script->scriptSource();
         SourceSet::AddPtr entry = closure->seenSources.lookupForAdd(ss);
         if (!entry) {
             closure->seenSources.add(entry, ss); // Not much to be done on failure.
             rtStats->runtime.scriptSources += ss->sizeOfIncludingThis(rtStats->mallocSizeOf);
diff --git a/js/src/jsscript.cpp b/js/src/jsscript.cpp
--- a/js/src/jsscript.cpp
+++ b/js/src/jsscript.cpp
@@ -1901,18 +1901,17 @@ JSScript::finalize(FreeOp *fop)
         JS_DropPrincipals(fop->runtime(), originPrincipals);
 
     if (types)
         types->destroy();
 
 #ifdef JS_METHODJIT
     mjit::ReleaseScriptCode(fop, this);
 # ifdef JS_ION
-    if (hasIonScript())
-        ion::IonScript::Destroy(fop, ion);
+    ion::DestroyIonScripts(fop, this);
 # endif
 #endif
 
     destroyScriptCounts(fop);
     destroyDebugScript(fop);
     scriptSource_->decref(fop->runtime());
 
     if (data) {
@@ -2594,18 +2593,17 @@ JSScript::markChildren(JSTracer *trc)
         for (unsigned i = 0; i < length; i++) {
             BreakpointSite *site = debugScript()->breakpoints[i];
             if (site && site->trapHandler)
                 MarkValue(trc, &site->trapClosure, "trap closure");
         }
     }
 
 #ifdef JS_ION
-    if (hasIonScript())
-        ion::IonScript::Trace(trc, ion);
+    ion::TraceIonScripts(trc, this);
 #endif
 }
 
 void
 JSScript::setArgumentsHasVarBinding()
 {
     argsHasVarBinding_ = true;
     needsArgsAnalysis_ = true;
diff --git a/js/src/jsscript.h b/js/src/jsscript.h
--- a/js/src/jsscript.h
+++ b/js/src/jsscript.h
@@ -544,36 +544,60 @@ struct JSScript : public js::gc::Cell
      * canonical location for the arguments. Note: if a formal is aliased
      * through the scope chain, then script->formalIsAliased and JSOP_*ARG*
      * opcodes won't be emitted at all.
      */
     bool argsObjAliasesFormals() const {
         return needsArgsObj() && !strictModeCode;
     }
 
-    js::ion::IonScript *ion;          /* Information attached by Ion */
+    bool hasAnyIonScript() const {
+        return hasIonScript() || hasParallelIonScript();
+    }
 
-#if defined(JS_METHODJIT) && JS_BITS_PER_WORD == 32
-    void *padding_;
-#endif
+    /* Information attached by Ion: script for sequential mode execution */
+    js::ion::IonScript *ion;
 
     bool hasIonScript() const {
         return ion && ion != ION_DISABLED_SCRIPT && ion != ION_COMPILING_SCRIPT;
     }
+
     bool canIonCompile() const {
         return ion != ION_DISABLED_SCRIPT;
     }
+
     bool isIonCompilingOffThread() const {
         return ion == ION_COMPILING_SCRIPT;
     }
+
     js::ion::IonScript *ionScript() const {
         JS_ASSERT(hasIonScript());
         return ion;
     }
 
+    /* Information attached by Ion: script for parallel mode execution */
+    js::ion::IonScript *parallelIon;
+
+    bool hasParallelIonScript() const {
+        return parallelIon && parallelIon != ION_DISABLED_SCRIPT && parallelIon != ION_COMPILING_SCRIPT;
+    }
+
+    bool canParallelIonCompile() const {
+        return parallelIon != ION_DISABLED_SCRIPT;
+    }
+
+    bool isParallelIonCompilingOffThread() const {
+        return parallelIon == ION_COMPILING_SCRIPT;
+    }
+
+    js::ion::IonScript *parallelIonScript() const {
+        JS_ASSERT(hasParallelIonScript());
+        return parallelIon;
+    }
+
     /*
      * Original compiled function for the script, if it has a function.
      * NULL for global and eval scripts.
      */
     JSFunction *function() const { return function_; }
     void setFunction(JSFunction *fun);
 
     JSFlatString *sourceData(JSContext *cx);
diff --git a/js/src/jsworkers.cpp b/js/src/jsworkers.cpp
--- a/js/src/jsworkers.cpp
+++ b/js/src/jsworkers.cpp
@@ -3,16 +3,17 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "jsworkers.h"
 
 #if JS_ION
 # include "ion/IonBuilder.h"
+# include "ion/ExecutionModeInlines.h"
 #endif
 
 using namespace js;
 
 using mozilla::DebugOnly;
 
 #ifdef JS_PARALLEL_COMPILATION
 
@@ -289,17 +290,18 @@ WorkerThread::threadLoop()
                 state.unlock();
                 return;
             }
             state.wait(WorkerThreadState::WORKER);
         }
 
         ionBuilder = state.ionWorklist.popCopy();
 
-        JS_ASSERT(ionBuilder->script()->ion == ION_COMPILING_SCRIPT);
+        ion::ExecutionMode executionMode = ionBuilder->info().executionMode();
+        JS_ASSERT(GetIonScript(ionBuilder->script().unsafeGet(), executionMode) == ION_COMPILING_SCRIPT);
 
         state.unlock();
 
         {
             ion::IonContext ictx(NULL, ionBuilder->script()->compartment(), &ionBuilder->temp());
             ionBuilder->backgroundCompiledLir = ion::CompileBackEnd(ionBuilder);
         }
 
diff --git a/js/src/methodjit/Compiler.cpp b/js/src/methodjit/Compiler.cpp
--- a/js/src/methodjit/Compiler.cpp
+++ b/js/src/methodjit/Compiler.cpp
@@ -534,17 +534,17 @@ mjit::Compiler::performCompilation()
 
 #ifdef JS_METHODJIT
     outerScript->debugMode = debugMode();
 #endif
 
     JS_ASSERT(cx->compartment->activeInference);
 
     {
-        types::AutoEnterCompilation enter(cx, types::AutoEnterCompilation::JM);
+        types::AutoEnterCompilation enter(cx, types::CompilerOutput::MethodJIT);
         if (!enter.init(outerScript, isConstructing, chunkIndex)) {
             js_ReportOutOfMemory(cx);
             return Compile_Error;
         }
 
         CHECK_STATUS(checkAnalysis(outerScript));
         if (inlining())
             CHECK_STATUS(scanInlineCalls(CrossScriptSSA::OUTER_FRAME, 0));