When the callee requires a dynamic stack realignment,
it is not possible to correcty access the incoming
stack arguments using the stack pointer. We reserve a
base pointer in such cases to access the function arguments
inside the callee. The base pointer will hold the incoming
stack pointer value before any kind of delta added to it.
Reviewed By: arsenm, scott.linder
Differential Revision: https://reviews.llvm.org/D78811
If there were no free VGPRs we would need two emergency spill slots for register
scavenging during PEI/frame index elimination. Reuse 'ResultReg' for scale
calculation so that only one spill is needed.
Differential Revision: https://reviews.llvm.org/D76387
Add the scratch wave offset to the scratch buffer descriptor (SRSrc) in
the entry function prologue. This allows us to removes the scratch wave
offset register from the calling convention ABI.
As part of this change, allow the use of an inline constant zero for the
SOffset of MUBUF instructions accessing the stack in entry functions
when a frame pointer is not requested/required. Entry functions with
calls still need to set up the calling convention ABI stack pointer
register, and reference it in order to address arguments of called
functions. The ABI stack pointer register remains unswizzled, but is now
wave-relative instead of queue-relative.
Non-entry functions also use an inline constant zero SOffset for
wave-relative scratch access, but continue to use the stack and frame
pointers as before. When the stack or frame pointer is converted to a
swizzled offset it is now scaled directly, as the scratch wave offset no
longer needs to be subtracted first.
Update llvm/docs/AMDGPUUsage.rst to reflect these changes to the calling
convention.
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D75138
This was relying on the SGPR usable for the carry out clobber to also
be used for the input. There was no carry out on gfx9. With no carry
out clobber to worry about, so the literal can just be directly used
with a VOP2 add.
llvm-svn: 371791
Christudasan Devadasan