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[AMDGPU][MC] Added support of lds_direct operand
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Authored by dp on Feb 7 2019, 6:01 AM.

Details

Summary

See bug 39293: https://bugs.llvm.org/show_bug.cgi?id=39293

Known issues:

  • This is a simple implementation assuming that lds_direct support is not needed in codegen. The implementation will have to be completely rewritten in case lds_direct support is required in the future. This is because, for example, m0 has to be added to USES for instructions accessing lds_direct.
  • Not clear if lds_direct should be disabled for SDWA. AMD documentation is silent about SDWA but SP3 seems to disable it.
  • AMD documentation explicitly states which opcodes do not support lds_direct. However looks like that the list is incomplete as SP3 disables lds_direct for most 'rev' opcodes.
  • The enumeration of opcodes which do not support lds_direct is already long enough and may need to be expanded further. I was thinking about adding a TS flag to label the corresponding opcodes. However there are not many free bits left in TSFlags and I was reluctant to use a bit for this purpose.

What is missing:

  • This patch does not enable lds_direct for v_readfirstlane_b32, v_readlane_b32 and v_writelane_b32. This will be implemented by a separate patch.
  • Assembler documentation should be updated with a description of lds_support. This will be added by a separate patch.

Diff Detail

Repository
rL LLVM

Event Timeline

dp created this revision.Feb 7 2019, 6:01 AM
artem.tamazov accepted this revision.Feb 7 2019, 6:58 AM

Looks good from assember's side.

This revision is now accepted and ready to land.Feb 7 2019, 6:58 AM
Closed by commit rL353524: [AMDGPU][MC] Added support of lds_direct operand (authored by dpreobra, committed by ). · Explain WhyFeb 8 2019, 6:57 AM
This revision was automatically updated to reflect the committed changes.
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