MIPS: Fix for instanceof-proxies failure.

src/mips/code-stubs-mips.cc

Index: src/mips/code-stubs-mips.cc
diff --git a/src/mips/code-stubs-mips.cc b/src/mips/code-stubs-mips.cc
index 476f82eaf826bb73d160a815d916939b0e95750d..ce85ec7ab7f3627e7a3b1e737b4022176faad2e4 100644
--- a/src/mips/code-stubs-mips.cc
+++ b/src/mips/code-stubs-mips.cc
@@ -1529,6 +1529,9 @@ void InstanceOfStub::Generate(MacroAssembler* masm) {
   // Proxy-case: Call the %HasInPrototypeChain runtime function.
   __ bind(&proxy_case);
   __ Push(object, function_prototype);
+  // Invalidate the instanceof cache.
+  __ li(scratch, Operand(Smi::FromInt(0)));

[dusan.milosavljevic, 2015/12/12 02:40:25]

Can we use zero reg here?

[paul.l..., 2015/12/12 02:55:27]

Definitely we could use move from zero reg. But li() will be encoded as
addiu(scratch, zero_reg, 0), which is single instruction, and unlikely to take
any longer to execute (no memory refs). (With the mov() version, I'd feel
obligated to add an Assert that Smi::FromInt(0) is really zero:) Anyway, I don't
see a payoff for the mov(), do you?

[paul.l..., 2015/12/12 02:57:11]

Sorry, you are right, I missed it. I think I stopped the commit, I'll update the
CL.

+  __ StoreRoot(scratch, Heap::kInstanceofCacheFunctionRootIndex);
   __ TailCallRuntime(Runtime::kHasInPrototypeChain, 2, 1);
 
   // Slow-case: Call the %InstanceOf runtime function.