fixed-abi uses pre-defined and predictable
SGPR/VGPRs for passing arguments. This patch makes
this scheme default when HSA OS is specified in triple.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D96340
When SGPRs are spilled to VGPRs, they can overwrite any lane. We need
to preserve the value of inactive lanes in function calls, so we save
the register even if it is marked as caller saved.
Also, teach buildPrologSpill to work when no registers are free like in
CodeGen/AMDGPU/pei-scavenge-vgpr-spill.mir and update the comment on
findScratchNonCalleeSaveRegister as it is not used anymore to realign
the stack pointer since D95865.
Differential Revision: https://reviews.llvm.org/D95946
If a function has stack objects, and a call, we require an FP. If we
did not initially have any stack objects, and only introduced them
during PrologEpilogInserter for CSR VGPR spills, SILowerSGPRSpills
would end up spilling the FP register as if it were a normal
register. This would result in an assert in a debug build, or
redundant handling of the FP register in a release build.
Try to predict that we will have an FP later, although this is ugly.
madhur13490