[PATCH] D48661: [Fixed Point Arithmetic] Fixed Point Constant

[Leonard Chan via Phabricator via cfe-commits]

leonardchan created this revision.
leonardchan added reviewers: phosek, mcgrathr, jakehehrlich, rsmith, ebevhan, rjmccall.
leonardchan added a project: clang.

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.

Tests will be added next. Just wanted to expose the type now in case anyone has any early comments.


Repository:
  rC Clang

https://reviews.llvm.org/D48661

Files:
  include/clang/AST/ASTContext.h
  include/clang/Basic/FixedPoint.h
  include/clang/Basic/TargetInfo.h
  lib/AST/ASTContext.cpp
  lib/Sema/SemaExpr.cpp
  test/Frontend/fixed_point_declarations.c

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