Currently the return address ABI registers s[30:31], which fall in the call
clobbered register range, are added as a live-in on the function entry to
preserve its value when we have calls so that it gets saved and restored
around the calls.
But the DWARF unwind information (CFI) needs to track where the return address
resides in a frame and the above approach makes it difficult to track the
return address when the CFI information is emitted during the frame lowering,
due to the involvment of understanding the control flow.
This patch moves the return address ABI registers s[30:31] into callee saved
registers range and stops adding live-in for return address registers, so that
the CFI machinery will know where the return address resides when CSR
save/restore happen during the frame lowering.
And doing the above poses an issue that now the return instruction uses undefined
register `sgpr30_sgpr31`. This is resolved by hiding the return address register
use by the return instruction through the `SI_RETURN` pseudo instruction, which
doesn't take any input operands, until the `SI_RETURN` pseudo gets lowered to the
`S_SETPC_B64_return` during the `expandPostRAPseudo()`.
As an added benefit, this patch simplifies overall return instruction handling.
Note: The AMDGPU CFI changes are there only in the downstream code and another
version of this patch will be posted for review for the downstream code.
Reviewed By: arsenm, ronlieb
Differential Revision: https://reviews.llvm.org/D114652
Currently the return address ABI registers s[30:31], which fall in the call
clobbered register range, are added as a live-in on the function entry to
preserve its value when we have calls so that it gets saved and restored
around the calls.
But the DWARF unwind information (CFI) needs to track where the return address
resides in a frame and the above approach makes it difficult to track the
return address when the CFI information is emitted during the frame lowering,
due to the involvment of understanding the control flow.
This patch moves the return address ABI registers s[30:31] into callee saved
registers range and stops adding live-in for return address registers, so that
the CFI machinery will know where the return address resides when CSR
save/restore happen during the frame lowering.
And doing the above poses an issue that now the return instruction uses undefined
register `sgpr30_sgpr31`. This is resolved by hiding the return address register
use by the return instruction through the `SI_RETURN` pseudo instruction, which
doesn't take any input operands, until the `SI_RETURN` pseudo gets lowered to the
`S_SETPC_B64_return` during the `expandPostRAPseudo()`.
As an added benefit, this patch simplifies overall return instruction handling.
Note: The AMDGPU CFI changes are there only in the downstream code and another
version of this patch will be posted for review for the downstream code.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D114652
The combined vector register classes with both
VGPRs and AGPRs are currently unallocatable.
This patch turns them into allocatable as a
prerequisite to enable copy between VGPR and
AGPR registers during regalloc.
Also, added the missing AV register classes from
192b to 1024b.
Reviewed By: rampitec
Differential Revision: https://reviews.llvm.org/D109300
This patch changes the AMDGPU_Gfx calling convention. It defines the SGPR registers s[4:29] as callee-save and leaves some SGPRs usable for callers. The intention is to avoid unneccessary s_mov instructions for arguments the caller would otherwise save and restore in these registers.
Reviewed By: sebastian-ne
Differential Revision: https://reviews.llvm.org/D111637
gfx90a operations require even aligned registers, but this was
previously achieved by reserving registers inside the full class.
Ideally this would be captured in the static instruction definitions
for the operands, and we would have different instructions per
subtarget. The hackiest part of this is we need to manually reassign
AGPR register classes after instruction selection (we get away without
this for VGPRs since those types are actually registered for legal
types).
We don't register i128 as a legal type with addRegisterClass, but it
appears in the list of legal register types. This inconsistency
resulted in the asm constraint lowering trying to use 2 128-bit
registers for these operands. This would leave behind a dead def that
would waste registers.
Regresses GlobalISel tests for i128 load/store, but these aren't very
important right now. Ideally these would not depend on the list of
register types.
