[Fixed Point Arithmetic] Fixed Point Constant

This patch proposes an abstract type that represents fixed point numbers, similar to APInt or APSInt that was discussed in https://reviews.llvm.org/D48456#inline-425585. This type holds a value, scale, and saturation and is meant to perform intermediate calculations on constant fixed point values.

Currently this class is used as a way for handling the conversions between fixed point numbers with different sizes and radixes. For example, if I'm casting from a signed _Accum to a saturated unsigned short _Accum, I will need to check the value of the signed _Accum to see if it fits into the short _Accum which involves getting and comparing against the max/min values of the short _Accum. The FixedPointNumber class currently handles the radix shifting and extension when converting to a signed _Accum.

Differential Revision: https://reviews.llvm.org/D48661

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@339028 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 0 deletions

diff --git a/include/clang/Basic/TargetInfo.h b/include/clang/Basic/TargetInfo.h
index f91f7761da..c3ef56110b 100644
--- a/include/clang/Basic/TargetInfo.h
+++ b/include/clang/Basic/TargetInfo.h
@@ -312,6 +312,14 @@ public:
     }
   }
 
+  /// In the event this target uses the same number of fractional bits for its
+  /// unsigned types as it does with its signed counterparts, there will be
+  /// exactly one bit of padding.
+  /// Return true if unsigned fixed point types have padding for this target.
+  bool doUnsignedFixedPointTypesHavePadding() const {
+    return PaddingOnUnsignedFixedPoint;
+  }
+
   /// Return the width (in bits) of the specified integer type enum.
   ///
   /// For example, SignedInt -> getIntWidth().