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

src/IceAPInt.h

Index: src/IceAPInt.h
diff --git a/src/IceAPInt.h b/src/IceAPInt.h
new file mode 100644
index 0000000000000000000000000000000000000000..d117f0a49e5d82b6d7902564bbdb2c6221917899
--- /dev/null
+++ b/src/IceAPInt.h
@@ -0,0 +1,63 @@
+//===-- 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.
+  SizeT APINT_BITS_PER_WORD =

[Jim Stichnoth, 2014/12/12 21:54:16]

This should be static const, or an enum value.

[Karl, 2014/12/12 22:46:12]

Done.

+      static_cast<uint32_t>(sizeof(uint64_t)) * CHAR_BIT;

[Jim Stichnoth, 2014/12/12 21:54:16]

I'm not sure the static_cast is actually needed, but if it is, wouldn't it be
better to static_cast<SizeT>(...) ?

[Karl, 2014/12/12 22:46:12]

Simplified.

+
+  APInt(SizeT Bits, uint64_t Val) : BitWidth(Bits), Val(Val) {
+    assert(BitWidth && "bitwidth too small");
+    assert(Bits <= APINT_BITS_PER_WORD && "bitwidth too big");

[Jim Stichnoth, 2014/12/12 21:54:16]

Use Bits in both asserts, or BitWidth in both asserts, for consistency.

[Karl, 2014/12/12 22:46:12]

Done.

+    clearUnusedBits();
+  }
+
+  uint32_t getBitWidth() const { return BitWidth; }
+
+  uint64_t getSExtValue() const {

[Jim Stichnoth, 2014/12/12 21:54:16]

Should this return int64_t like the llvm::ConstantInt version?

[Karl, 2014/12/12 22:46:12]

Done.

+    return static_cast<int64_t>((Val << (APINT_BITS_PER_WORD - BitWidth)) >>

[Karl, 2014/12/12 22:46:13]

Bug was missing parenthesis before last ">>" on line. Fixed.

+                                (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