The magnitude range of normalized _Float16 is 2^-14 (~6e-5) to
(2-2^-10)*2^15 (65504). You might think, then, that the code is
correct to defne FLT16_MIN_EXP and FLT16_MAX_EXP to be -14 and 15
respectively. However, for some reason the C specification actually
specifies a bias for these macros:
C11 5.2.4.2.2:
- minimum negative integer such that FLT_RADIX raised to one less than
that power is a normalized floating-point number, e_min:
FLT_MIN_EXP
DBL_MIN_EXP
LDBL_MIN_EXP
- maximum integer such that FLT_RADIX raised to one less than that
power is a representable finite floating-point number, e_max:
FLT_MAX_EXP
DBL_MAX_EXP
LDBL_MAX_EXP
FLT16_MIN_EXP and FLT16_MAX_EXP should clearly be biased the same way,
and other compilers do in fact do so, as do our OpenCL headers for `half`.
Additionally, FLT16_MIN_10_EXP is just wrong.
llvm-svn: 362183
We unconditionally predefine these macros. However, they may be used to
determine if the type is supported. In that case, there are unnecessary
failures to compile the code.
This is the proposed fix for https://bugs.llvm.org/show_bug.cgi?id=40559
Differential revision: https://reviews.llvm.org/D57577
llvm-svn: 354512
John McCall