Diana Picus f2e8e2faff
[AMDGPU] Make chain functions receive a stack pointer (#184616)
Currently, chain functions are free to set up a stack pointer if they
need one, and they assume they can start at scratch offset 0. This is
not correct if CWSR and dynamic VGPRs are both enabled, since in that
case we need to reserve an area at offset 0 for the trap handler, but
only when running on a compute queue (which we determine at runtime).
Rather than duplicate in every chain function the code sequence for
determining if/how much scratch space needs to be reserved, this patch
changes the ABI of chain functions so that they receive a stack pointer
from their caller.

Since chain functions can no longer use plain offsets to access their
own stack, we'll also need to allocate a frame pointer more often (and
sometimes also a base pointer). For simplicity, we use the same
registers that `amdgpu_gfx` functions do (s32, s33, s34). This may
change in the future. Chain functions never return to their caller and
thus don't need to preserve the frame or base pointer.

Another consequence is that now we might need to realign the stack in
some cases (since it no longer starts at the infinitely aligned 0).
2026-03-06 11:01:42 +01:00
..
2025-12-05 12:39:50 +00:00
2025-12-05 12:39:50 +00:00
2025-12-05 12:39:50 +00:00

+==============================================================================+
| How to organize the lit tests                                                |
+==============================================================================+

- If you write a test for matching a single DAG opcode or intrinsic, it should
  go in a file called {opcode_name,intrinsic_name}.ll (e.g. fadd.ll)

- If you write a test that matches several DAG opcodes and checks for a single
  ISA instruction, then that test should go in a file called {ISA_name}.ll (e.g.
  bfi_int.ll

- For all other tests, use your best judgement for organizing tests and naming
  the files.

+==============================================================================+
| Naming conventions                                                           |
+==============================================================================+

- Use dash '-' and not underscore '_' to separate words in file names, unless
  the file is named after a DAG opcode or ISA instruction that has an
  underscore '_' in its name.