The LIT test cases were migrated with the script provided by
Nikita Popov.
No manual changes were made. Committed without review since
no functional changes, after consultation with uweigand.
Memset with a constant length was implemented with a single store followed by
a series of MVC:s. This patch changes this so that one store of the byte is
emitted for each MVC, which avoids data dependencies between the MVCs. An
MVI/STC + MVC(len-1) is done for each block.
In addition, memset with a variable length is now also handled without a
libcall. Since the byte is first stored and then MVC is used from that
address, a length of two must now be subtracted instead of one for the loop
and EXRL. This requires an extra check for the one-byte case, which is
handled in a special block with just a single MVI/STC (like GCC).
Review: Ulrich Weigand
Differential Revision: https://reviews.llvm.org/D112004
