Changes

[Codegen] Emit both AssumeAlignedAttr and AllocAlignAttr assumptions if
they exist
Summary: We shouldn't be just giving up if we find one of them
(like we currently do with `AssumeAlignedAttr`), we should emit them
all.
As the tests show, even if we materialized good knowledge from
`__attribute__((assume_aligned(32)`, it doesn't mean
`__attribute__((alloc_align([...])))` info won't be useful. It might be,
but that isn't given.
Reviewers: erichkeane, jdoerfert, aaron.ballman
Reviewed By: erichkeane
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D72979

[NFC][Codegen] Use MaybeAlign + APInt::getLimitedValue() when creating
Alignment attr
Summary: Just an NFC code cleanup i stumbled upon when stumbling through
clang alignment attribute handling.
Reviewers: erichkeane, gchatelet, courbet, jdoerfert
Reviewed By: gchatelet
Subscribers: cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D72993

[APFloat] Extend conversion from special strings
Add support for converting Signaling NaN, and a NaN Payload from string.
The NaNs (the string "nan" or "NaN") may be prefixed with 's' or 'S' for
defining a Signaling NaN.
A payload for a NaN can be specified as a suffix. It may be a
octal/decimal/hexadecimal number in parentheses or without.
Differential Revision: https://reviews.llvm.org/D69773