[amdgpu] Implement lds kernel id intrinsic

Implement an intrinsic for use lowering LDS variables to different
addresses from different kernels. This will allow kernels that cannot
reach an LDS varia

[amdgpu] Implement lds kernel id intrinsic

Implement an intrinsic for use lowering LDS variables to different
addresses from different kernels. This will allow kernels that cannot
reach an LDS variable to avoid wasting space for it.

There are a number of implicit arguments accessed by intrinsic already
so this implementation closely follows the existing handling. It is slightly
novel in that this SGPR is written by the kernel prologue.

It is necessary in the general case to put variables at different addresses
such that they can be compactly allocated and thus necessary for an
indirect function call to have some means of determining where a
given variable was allocated. Claiming an arbitrary SGPR into which
an integer can be written by the kernel, in this implementation based
on metadata associated with that kernel, which is then passed on to
indirect call sites is sufficient to determine the variable address.

The intent is to emit a __const array of LDS addresses and index into it.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D125060

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[AMDGPU][NFC] Refactor AMDGPUCallingConv.td

Rename CalleeSavedRegs defs to avoid being overly specific:

* CSR_AMDGPU_AGPRs_32_255 => CSR_AMDGPU_AGPRs
* CSR_AMDGPU_SGPRs_30_31 + CSR_AMDGPU_SGPRs_32_

[AMDGPU][NFC] Refactor AMDGPUCallingConv.td

Rename CalleeSavedRegs defs to avoid being overly specific:

* CSR_AMDGPU_AGPRs_32_255 => CSR_AMDGPU_AGPRs
* CSR_AMDGPU_SGPRs_30_31 + CSR_AMDGPU_SGPRs_32_105 => CSR_AMDGPU_SGPRs
* CSR_AMDGPU_SI_Gfx_SGPRs_4_29 + CSR_AMDGPU_SI_Gfx_SGPRs_64_105 =>
CSR_AMDGPU_SI_Gfx_SGPRs
* CSR_AMDGPU_HighRegs => CSR_AMDGPU
* CSR_AMDGPU_HighRegs_With_AGPRs => CSR_AMDGPU_GFX90AInsts
* CSR_AMDGPU_SI_Gfx_With_AGPRs => CSR_AMDGPU_SI_Gfx_GFX90AInsts

Introduce a class RegMask to mark the cases where we use the
CalleeSavedRegs class purely as an expedient way to produce a mask.
Update the names of these masks to not mention "CSR". Other targets also
seem to do this, so a reasonable alternative is to actually update
table-gen to include a new class to do this explicitly, but the current
approach seems harmless so I opted to just make it more explicit.

Reviewed By: arsenm, sebastian-ne

Differential Revision: https://reviews.llvm.org/D109008

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[AMDGPU] Move call clobbered return address registers s[30:31] to callee saved range

Currently the return address ABI registers s[30:31], which fall in the call
clobbered register range, are added a

[AMDGPU] Move call clobbered return address registers s[30:31] to callee saved range

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

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GlobalISel: Pass DebugLoc to getFunctionLiveInPhysReg

Fixes crash in assertion about dropping debug info.