[turbofan] Use CompareNilIC for abstract equality with null/undefined.

src/full-codegen/ppc/full-codegen-ppc.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_PPC
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
 #include "src/debug/debug.h"
@@ skipping 4939 matching lines @@
   if (expr->op() == Token::EQ_STRICT) {
     Heap::RootListIndex nil_value = nil == kNullValue
                                         ? Heap::kNullValueRootIndex
                                         : Heap::kUndefinedValueRootIndex;
     __ LoadRoot(r4, nil_value);
     __ cmp(r3, r4);
     Split(eq, if_true, if_false, fall_through);
   } else {
     Handle<Code> ic = CompareNilICStub::GetUninitialized(isolate(), nil);
     CallIC(ic, expr->CompareOperationFeedbackId());
-    __ cmpi(r3, Operand::Zero());
-    Split(ne, if_true, if_false, fall_through);
+    __ CompareRoot(r3, Heap::kTrueValueRootIndex);
+    Split(eq, if_true, if_false, fall_through);
   }
   context()->Plug(if_true, if_false);
 }
 
 
 void FullCodeGenerator::VisitThisFunction(ThisFunction* expr) {
   __ LoadP(r3, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
   context()->Plug(r3);
 }
 
@@ skipping 170 matching lines @@
     return ON_STACK_REPLACEMENT;
   }
 
   DCHECK(interrupt_address ==
          isolate->builtins()->OsrAfterStackCheck()->entry());
   return OSR_AFTER_STACK_CHECK;
 }
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_TARGET_ARCH_PPC