[llvm] r271380 - Fix off-by-one error in max integer functions

[David Blaikie via llvm-commits]

Please include/provide a test case - these could probably use a bunch of
unit tests.

On Wed, Jun 1, 2016 at 4:15 AM, Dylan McKay via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> Author: dylanmckay
> Date: Wed Jun  1 06:15:25 2016
> New Revision: 271380
>
> URL: http://llvm.org/viewvc/llvm-project?rev=271380&view=rev
> Log:
> Fix off-by-one error in max integer functions
>
> I recently added these functions, but implemented them poorly. This
> fixes that.
>
> Sorry for the spam.
>
> Modified:
>     llvm/trunk/include/llvm/Support/MathExtras.h
>
> Modified: llvm/trunk/include/llvm/Support/MathExtras.h
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/MathExtras.h?rev=271380&r1=271379&r2=271380&view=diff
>
> ==============================================================================
> --- llvm/trunk/include/llvm/Support/MathExtras.h (original)
> +++ llvm/trunk/include/llvm/Support/MathExtras.h Wed Jun  1 06:15:25 2016
> @@ -312,22 +312,22 @@ inline bool isShiftedUInt(uint64_t x) {
>  }
>
>  /// Gets the maximum value for a N-bit unsigned integer.
> -inline uint64_t maxUIntN(uint64_t N) { return UINT64_C(1) << N; }
> +inline uint64_t maxUIntN(uint64_t N) { return (UINT64_C(1) << N) - 1; }
>  /// Gets the minimum value for a N-bit signed integer.
>  inline int64_t minIntN(int64_t N) { return -(INT64_C(1)<<(N-1)); }
>  /// Gets the maximum value for a N-bit signed integer.
> -inline int64_t maxIntN(int64_t N) { return INT64_C(1)<<(N-1); }
> +inline int64_t maxIntN(int64_t N) { return (INT64_C(1)<<(N-1)) - 1; }
>
>  /// isUIntN - Checks if an unsigned integer fits into the given (dynamic)
>  /// bit width.
>  inline bool isUIntN(unsigned N, uint64_t x) {
> -  return N >= 64 || x < maxUIntN(N);
> +  return N >= 64 || x <= maxUIntN(N);
>  }
>
>  /// isIntN - Checks if an signed integer fits into the given (dynamic)
>  /// bit width.
>  inline bool isIntN(unsigned N, int64_t x) {
> -  return N >= 64 || (minIntN(N) <= x && x < maxIntN(N));
> +  return N >= 64 || (minIntN(N) <= x && x <= maxIntN(N));
>  }
>
>  /// isMask_32 - This function returns true if the argument is a non-empty
>
>
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