Jeffrey Byrnes 7bcf4d63cf
[AMDGPU] Correctly insert s_nops for dst forwarding hazard (#100276)
MI300 ISA section 4.5 states there is a hazard between "VALU op which
uses OPSEL or SDWA with changes the result’s bit position" and "VALU op
consumes result of that op"

This includes the case where the second op is SDWA with same dest and
dst_sel != DWORD && dst_unused == UNUSED_PRESERVE. In this case, there
is an implicit read of the first op dst and the compiler needs to
resolve this hazard. Confirmed with HW team.

We model dst_unused == UNUSED_PRESERVE as tied-def of implicit operand,
so this PR checks for that.

MI300_SP_MAS section 1.3.9.2 specifies that CVT_SR_FP8_F32 and
CVT_SR_BF8_F32 with opsel[3:2] !=0 have dest forwarding issue.
Currently, we only add check for CVT_SR_FP8_F32 with opsel[3] != 0 --
this PR adds support opsel[2] != 0 as well
2024-08-22 11:38:24 -07:00
..
2024-06-14 16:45:11 -07:00
2024-07-31 10:27:33 +01:00

+==============================================================================+
| 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.