Changes

[X86] Fix tile spill merge issue.

This is a additional bug fix for c5be0e0cc0. The distance for
the spill instructions is wrong in previous patch.

Differential Revision: https://reviews.llvm.org/D94772

PR48763: Better handling for classes that inherit a default constructor.

The C++ standard wording doesn't appear to properly handle the case
where a class inherits a default constructor from a base class. Various
properties of classes are defined in terms of the corresponding property
of the default constructor, and in this case, the class does not have a
default constructor despite being default-constructible, which the
wording doesn't handle properly.

This change implements a tentative fix for these problems, which has
also been proposed to the C++ committee: if a class would inherit a
default constructor, and does not explicitly declare one, then one is
implicitly declared.

[PowerPC] Sign extend comparison operand for signed atomic comparisons

As of 8dacca943af8a53a23b1caf3142d10fb4a77b645, we sign extend the atomic loaded
operand for signed subword comparisons. However, the assumption that the other
operand is correctly sign extended doesn't always hold. This patch sign extends
the other operand if it needs to be sign extended.

This is a second fix for https://bugs.llvm.org/show_bug.cgi?id=30451

Differential revision: https://reviews.llvm.org/D94058

[X86][AMX] Clear AMX lit test case.

Add nounwind attribute to avoid generating cfi instructions. Also make
global buffer 64 bytes align in lit test case.

Differential Revision: https://reviews.llvm.org/D94910