[GHC] #12412: SIMD things introduce a metric ton of known key things
#12412: SIMD things introduce a metric ton of known key things -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | performance bug Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- In #12357 we were looking at reducing the number of entries in the `knownKeyNames`. This has the potential to improve compiler performance since this set of things is always present in the original name cache, which is often referred to. #12357 reduced the number of elements in `knownKeyNames` from 2017 to 1834. Not a bad improvement. That being said, the SIMD operations introduce nearly four times that number. These include things like `readWord64OffAddrAsWord64X2#`, `indexInt16OffAddrAsInt16X16#`, and `remInt16X16#`. All in all these operations constitute nearly a third of the known key names. I'm not really sure what can be done about this, but I thought it should be noted. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12412 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#12412: SIMD things introduce a metric ton of known key things -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): As far as I know, nothing in #12357 suggested that the size of the `knownKeyNames` had the slightest impact on performance. I'm very un- bothered by the number of `knownKeyNames` until I see evidence that it has some impact. Why shoudl we care? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12412#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#12412: SIMD things introduce a metric ton of known key things -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by bgamari):
As far as I know, nothing in #12357 suggested that the size of the `knownKeyNames` had the slightest impact on performance.
It's not clear that we should. I merely opened this ticket so I had someplace to write the answer when I find out whether this is something worth worrying about, otherwise I would have surely forgotten. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12412#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#12412: SIMD things introduce a metric ton of known key things -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: low | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: SIMD Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * keywords: => SIMD -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12412#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
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