Add a basic TargetARM32 skeleton which knows nothing.

src/IceRegistersARM32.h

Index: src/IceRegistersARM32.h
diff --git a/src/IceRegistersARM32.h b/src/IceRegistersARM32.h
new file mode 100644
index 0000000000000000000000000000000000000000..2ad1c8b36adef2dfb57836cd13efb255f2b47347
--- /dev/null
+++ b/src/IceRegistersARM32.h
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+//===- subzero/src/IceRegistersARM32.h - Register information ---*- C++ -*-===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the registers and their encodings for ARM32.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SUBZERO_SRC_ICEREGISTERSARM32_H
+#define SUBZERO_SRC_ICEREGISTERSARM32_H
+
+#include "IceDefs.h"
+#include "IceInstARM32.def"
+#include "IceTypes.h"
+
+namespace Ice {
+
+namespace RegARM32 {
+
+// An enum of every register. The enum value may not match the encoding
+// used to binary encode register operands in instructions.
+enum AllRegisters {
+#define X(val, encode, name, scratch, preserved, stackptr, frameptr, isInt,    \
+          isFP)                                                                \
+  val,
+  REGARM32_TABLE
+#undef X
+      Reg_NUM,
+#define X(val, init) val init,
+  REGARM32_TABLE_BOUNDS
+#undef X
+};
+
+// An enum of GPR Registers. The enum value does match the encoding used
+// to binary encode register operands in instructions.
+enum GPRRegister {
+#define X(val, encode, name, scratch, preserved, stackptr, frameptr, isInt,    \
+          isFP)                                                                \
+  Encoded_##val encode,
+  REGARM32_GPR_TABLE
+#undef X
+      Encoded_Not_GPR = -1
+};
+
+// TODO(jvoung): Floating point and vector registers...
+// Need to model overlap and difference in encoding too.
+
+static inline GPRRegister getEncodedGPR(int32_t RegNum) {
+  assert(Reg_GPR_First <= RegNum && RegNum <= Reg_GPR_Last);
+  return GPRRegister(RegNum - Reg_GPR_First);
+}
+
+} // end of namespace RegARM32
+
+} // end of namespace Ice
+
+#endif // SUBZERO_SRC_ICEREGISTERSARM32_H