PPC: simplify delta calculation in DoDeferredInstanceOfKnownGlobal.

... and improve protection against trampoline table generation in this
sequence.

R=danno@chromium.org, svenpanne@chromium.org

BUG=

Review URL: https://codereview.chromium.org/985933003

Cr-Commit-Position: refs/heads/master@{#27146}

src/ppc/lithium-codegen-ppc.cc

@@ -2941,22 +2941,25 @@ void LCodeGen::DoDeferredInstanceOfKnownGlobal(LInstanceOfKnownGlobal* instr,
   LoadContextFromDeferred(instr->context());
 
   __ Move(InstanceofStub::right(), instr->function());
-  // Include instructions below in delta: mov + call = mov + (mov + 2)
-  static const int kAdditionalDelta = 2 * Assembler::kMovInstructions + 2;
-  int delta = masm_->InstructionsGeneratedSince(map_check) + kAdditionalDelta;
   {
     Assembler::BlockTrampolinePoolScope block_trampoline_pool(masm_);
-    if (Assembler::kMovInstructions != 1 &&
-        is_int16(delta * Instruction::kInstrSize)) {
-      // The following mov will be an li rather than a multi-instruction form
-      delta -= Assembler::kMovInstructions - 1;
-    }
+    Handle<Code> code = stub.GetCode();
+    // Include instructions below in delta: bitwise_mov32 + call
+    int delta = (masm_->InstructionsGeneratedSince(map_check) + 2) *
+                    Instruction::kInstrSize +
+                masm_->CallSize(code);
     // r8 is used to communicate the offset to the location of the map check.
-    __ mov(r8, Operand(delta * Instruction::kInstrSize));
+    if (is_int16(delta)) {
+      delta -= Instruction::kInstrSize;
+      __ li(r8, Operand(delta));
+    } else {
+      __ bitwise_mov32(r8, delta);
+    }
+    CallCodeGeneric(code, RelocInfo::CODE_TARGET, instr,
+                    RECORD_SAFEPOINT_WITH_REGISTERS_AND_NO_ARGUMENTS);
+    DCHECK(delta / Instruction::kInstrSize ==
+           masm_->InstructionsGeneratedSince(map_check));
   }
-  CallCodeGeneric(stub.GetCode(), RelocInfo::CODE_TARGET, instr,
-                  RECORD_SAFEPOINT_WITH_REGISTERS_AND_NO_ARGUMENTS);
-  DCHECK(delta == masm_->InstructionsGeneratedSince(map_check));
   LEnvironment* env = instr->GetDeferredLazyDeoptimizationEnvironment();
   safepoints_.RecordLazyDeoptimizationIndex(env->deoptimization_index());
   // Put the result value (r3) into the result register slot and