Simplify LLVM's APInt and APFloat for use in Subzero.

src/IceAPInt.h

+//===-- subzero/src/IceAPInt.h - Constant integer conversions --*- C++ -*--===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief This file implements a class to represent 64 bit integer constant
+/// values, and thier conversion to variable bit sized integers.
+///
+/// Note: This is a simplified version of llvm/include/llvm/ADT/APInt.h for use
+/// with Subzero.
+//===----------------------------------------------------------------------===//
+
+#ifndef SUBZERO_SRC_ICEAPINT_H
+#define SUBZERO_SRC_ICEAPINT_H
+
+#include "IceDefs.h"
+
+namespace Ice {
+
+class APInt {
+public:
+  /// Bits in an (internal) value.
+  static const SizeT APINT_BITS_PER_WORD = sizeof(uint64_t) * CHAR_BIT;
+
+  APInt(SizeT Bits, uint64_t Val) : BitWidth(Bits), Val(Val) {
+    assert(Bits && "bitwidth too small");
+    assert(Bits <= APINT_BITS_PER_WORD && "bitwidth too big");
+    clearUnusedBits();
+  }
+
+  uint32_t getBitWidth() const { return BitWidth; }
+
+  int64_t getSExtValue() const {
+    return static_cast<int64_t>(Val << (APINT_BITS_PER_WORD - BitWidth)) >>
+           (APINT_BITS_PER_WORD - BitWidth);
+  }
+
+  uint64_t getRawData() const { return Val; }
+
+private:
+  uint32_t BitWidth; // The number of bits in this APInt.
+  uint64_t Val;      // The (64-bit) equivalent integer value.
+
+  /// Clear unused high order bits.
+  void clearUnusedBits() {
+    // If all bits are used, we want to leave the value alone.
+    if (BitWidth == APINT_BITS_PER_WORD)
+      return;
+
+    // Mask out the high bits.
+    Val &= ~static_cast<uint64_t>(0) >> (APINT_BITS_PER_WORD - BitWidth);
+  }
+};
+
+} // end of namespace Ice
+
+#endif // SUBZERO_SRC_ICEAPINT_H