Bug 881366 - Simplify CheckOverrecursed sequences. r=sstangl

js/src/ion/CodeGenerator.cpp

@@ -2130,19 +2130,17 @@ CodeGenerator::visitCheckOverRecursed(LCheckOverRecursed *lir)
     // C functions may then violate the limit without any checking.
 
     JSRuntime *rt = gen->compartment->rt;
-    Register limitReg = ToRegister(lir->limitTemp());
 
     // Since Ion frames exist on the C stack, the stack limit may be
     // dynamically set by JS_SetThreadStackLimit() and JS_SetNativeStackQuota().
     uintptr_t *limitAddr = &rt->mainThread.ionStackLimit;
-    masm.loadPtr(AbsoluteAddress(limitAddr), limitReg);
 
     CheckOverRecursedFailure *ool = new CheckOverRecursedFailure(lir);
     if (!addOutOfLineCode(ool))
         return false;
 
     // Conditional forward (unlikely) branch to failure.
-    masm.branchPtr(Assembler::BelowOrEqual, StackPointer, limitReg, ool->entry());
+    masm.branchPtr(Assembler::AboveOrEqual, AbsoluteAddress(limitAddr), StackPointer, ool->entry());
     masm.bind(ool->rejoin());
 
     return true;

js/src/ion/LIR-Common.h

@@ -544,18 +544,13 @@ class LInitProp : public LCallInstructionHelper<0, 1 + BOX_PIECES, 0>
     }
 };
 
-class LCheckOverRecursed : public LInstructionHelper<0, 0, 1>
+class LCheckOverRecursed : public LInstructionHelper<0, 0, 0>
 {
   public:
     LIR_HEADER(CheckOverRecursed)
 
-    LCheckOverRecursed(const LDefinition &limitreg) {
-        setTemp(0, limitreg);
-    }
-
-    const LAllocation *limitTemp() {
-        return getTemp(0)->output();
-    }
+    LCheckOverRecursed()
+    { }
 };
 
 class LParCheckOverRecursed : public LInstructionHelper<0, 1, 1>

js/src/ion/Lowering.cpp

@@ -102,7 +102,7 @@ LIRGenerator::visitTableSwitch(MTableSwitch *tableswitch)
 bool
 LIRGenerator::visitCheckOverRecursed(MCheckOverRecursed *ins)
 {
-    LCheckOverRecursed *lir = new LCheckOverRecursed(temp());
+    LCheckOverRecursed *lir = new LCheckOverRecursed();
 
     if (!add(lir))
         return false;

js/src/jscntxt.cpp

@@ -1081,7 +1081,7 @@ js_InvokeOperationCallback(JSContext *cx)
      */
     JS_ATOMIC_SET(&rt->interrupt, 0);
 
-    /* IonMonkey sets its stack limit to NULL to trigger operaton callbacks. */
+    /* IonMonkey sets its stack limit to UINTPTR_MAX to trigger operaton callbacks. */
     rt->resetIonStackLimit();
 
     if (rt->gcIsNeeded)