MIPS: Fix trampoline pool handling in MacroAssembler::BranchShort() for r6.

test/cctest/test-assembler-mips64.cc

Index: test/cctest/test-assembler-mips64.cc
diff --git a/test/cctest/test-assembler-mips64.cc b/test/cctest/test-assembler-mips64.cc
index 8fda0d290f43e027782b40f4ad39b0812013fdec..79aa6162095181455276347c0afe4fb525f8dbdc 100644
--- a/test/cctest/test-assembler-mips64.cc
+++ b/test/cctest/test-assembler-mips64.cc
@@ -5492,4 +5492,38 @@ TEST(bal) {
 }
 
 
+TEST(Trampoline) {
+  if (kArchVariant == kMips64r6) {
+    // Private member of Assembler class.
+    static const int kMaxBranchOffset = (1 << (18 - 1)) - 1;
+
+    CcTest::InitializeVM();
+    Isolate* isolate = CcTest::i_isolate();
+    HandleScope scope(isolate);
+
+    MacroAssembler assm(isolate, NULL, 0);
+    Label done;
+    size_t nr_calls = kMaxBranchOffset / (2 * Instruction::kInstrSize) + 2;
+
+    __ stop("check.");
+    for (size_t i = 0; i < nr_calls; ++i) {
+      __ BranchShort(&done, eq, a0, Operand(a1));
+    }
+    __ bind(&done);
+    __ Ret(USE_DELAY_SLOT);
+    __ mov(v0, zero_reg);
+
+    CodeDesc desc;
+    assm.GetCode(&desc);
+    Handle<Code> code = isolate->factory()->NewCode(
+        desc, Code::ComputeFlags(Code::STUB), Handle<Code>());
+    F2 f = FUNCTION_CAST<F2>(code->entry());
+
+    int64_t res =
+        reinterpret_cast<int64_t>(CALL_GENERATED_CODE(f, 5, 5, 0, 0, 0));
+    CHECK_EQ(res, 0);
+  }
+}
+
+
 #undef __