[turbofan] Fix a bug in the RawMachineAssembler

test/cctest/compiler/test-branch-combine.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.
 
 #include "test/cctest/cctest.h"
 #include "test/cctest/compiler/codegen-tester.h"
 #include "test/cctest/compiler/value-helper.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 439 matching lines @@
                                                              : eq_constant)
                      : (cmp.Float64Compare(input_a, input_b) ? eq_constant
                                                              : ne_constant);
           CHECK_EQ(expected, m.Call());
         }
       }
     }
   }
 }
 
+#if V8_TARGET_ARCH_64_BIT
+TEST(BranchCombineWord64EqualZeroPhi) {
+  // Test combining a branch with a Word64Equal between a phi node and 0.
+  RawMachineAssemblerTester<int32_t> m(MachineType::AnyTagged());
+  uintptr_t something = 0x100000000;
+  uintptr_t null = 0;
+
+  Node* p0 = m.Parameter(0);
+
+  RawMachineLabel is_null, is_not_null, merge;
+  m.Branch(m.IntPtrEqual(p0, m.IntPtrConstant(0)), &is_null, &is_not_null);
+  m.Bind(&is_not_null);
+  Node* val = m.Load(MachineType::AnyTagged(), p0);
+  m.Goto(&merge);
+  m.Bind(&is_null);
+  Node* fail_val = m.IntPtrConstant(0);
+  m.Goto(&merge);
+
+  m.Bind(&merge);
+  Node* phi = m.Phi(MachineRepresentation::kTagged, val, fail_val);
+
+  RawMachineLabel pass, fail;
+  m.Branch(m.IntPtrEqual(phi, m.IntPtrConstant(0)), &pass, &fail);
+  m.Bind(&pass);
+  m.Return(m.Int32Constant(0));
+  m.Bind(&fail);
+  m.Return(m.Int32Constant(1));
+
+  CHECK_EQ(1, m.Call(reinterpret_cast<v8::internal::Object*>(&something)));
+  CHECK_EQ(0, m.Call(reinterpret_cast<v8::internal::Object*>(&null)));
+  CHECK_EQ(0, m.Call(static_cast<v8::internal::Object*>(nullptr)));
+}
+
+#endif
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8