- Use computeMaxCallFrameSize() in PEI::calculateCallFrameInfo() instead of duplicating the code.
- Set AdjustsStack in FinalizeISel instead of in computeMaxCallFrameSize().
addi sp, sp, 512 may be used to recover the sp in the epilogue
when stack size is larger than 2047(2^11 - 1), however, it can
not be compressed using C extension, and addi sp, sp, 496 is
able to be compressed, so try to use 496 as the ajust amount of
the fisrt sp if function doesn't need extra instructions after
adjust.
Reviewed By: wangpc
Differential Revision: https://reviews.llvm.org/D159431
For callee saved/restored operations, they mostly use the
following inst patterns,
sw rs2, offset(x2)
sd rs2, offset(x2)
fsw rs2, offset(x2)
fsd rs2, offset(x2)
lw rd, offset(x2)
ld rd, offset(x2)
flw rd, offset(x2)
fld rd, offset(x2)
and offset decides whether the instructions can be compressed.
now offset 2032 will be set by default if stacksize is bigger
than 2^12-1 to save and restore callee saved register, so it
will prevent all the callee saved/restored stack insts be
compressed.
Allocating proper offset for stack insts is useful to make
them be compressed.
Reviewed By: craig.topper, wangpc
Differential Revision: https://reviews.llvm.org/D157373
