[AMDGPU] gfx1010 Avoid SMEM WAR hazard for some s_waitcnt values

Avoid introducing hazard mitigation when lgkmcnt is reduced to 0.
Clarify code comments to explain assumptions made for this hazard
mitigation.  Expand and correct test cases to cover variants of

Reviewers: nhaehnle, rampitec

Subscribers: arsenm, kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, t-tye, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62058

llvm-svn: 361124
2 files changed
tree: 1c5900c220ec59adccc132beefbec81ea5727d0f
  1. .arcconfig
  2. .clang-format
  3. .clang-tidy
  4. .gitignore
  5. README.md
  6. clang-tools-extra/
  7. clang/
  8. compiler-rt/
  9. debuginfo-tests/
  10. libclc/
  11. libcxx/
  12. libcxxabi/
  13. libunwind/
  14. lld/
  15. lldb/
  16. llgo/
  17. llvm/
  18. openmp/
  19. parallel-libs/
  20. polly/
  21. pstl/

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