[QST] CuTE - how to emit SASS loads with ".constant" suffix?
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Description
I've noticed that some cuBLASlt kernels on Ampere use this instruction for async gmem=>smem loads:
LDGSTS.E.BYPASS.LTC128B.128.CONSTANT
However, my own kernels using CuTE's SM80_CP_ASYNC_CACHEGLOBAL<uint128_t> use this instruction instead:
LDGSTS.E.BYPASS.LTC128B.128
I believe this may have something to do with the propagation of __restrict__ and const in CuTE. All my pointers are __restrict__ (and const where applicable) but it doesn't seem like the compiler is able to take advantage of this.
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Research direction
No source file or test is named. Start by locating CuTE's SM80_CP_ASYNC_CACHEGLOBAL<uint128_t> implementation and compare its generated SASS with the cuBLASLt instruction; done means determining whether const or restrict propagation can produce the .CONSTANT suffix.
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Assessment
- Tech stack
- cpp
- Domain
- performance
- Issue type
- Bug
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 25/100