It was discovered that an extra register COPY remained when expanding a
(variable length) memory operation with a loop and there was another use of
the involved address register(s) afterwards.
A simple fix for this is to COPY the address registers before the loop and
use that new vreg instead.
Review: Ulrich Weigand
Differential Revision: https://reviews.llvm.org/D112065
This patch fixes the bug that consisted of treating variable / immediate
length mem operations (such as memcpy, memset, ...) differently. The variable
length case needs to have the length minus 1 passed due to the use of EXRL
target instructions. However, the DAGCombiner can convert a register length
argument into a constant one, and whenever that happened one byte too little
would end up being performed.
This is also a refactorization by reducing the number of opcodes and variants
involved. For any opcode (variable or constant length), only the length minus
one is passed on to the ISD node. The rest of the logic is now instead
handled during isel pseudo expansion.
Review: Ulrich Weigand
Differential Revision: https://reviews.llvm.org/D111729
Benchmarking has shown that it is worthwhile to implement a variable length
memset of 0 with XC (exclusive or) like gcc does, instead of using a libcall.
This requires the use of the EXecute Relative Long (EXRL) instruction which
can now be done in a framework that can also be used with other target
instructions (not just XC).
Review: Ulrich Weigand
Differential Revision: https://reviews.llvm.org/D103865
Jonas Paulsson