[GHC] #5208: Unroll array copy/clone primops in the native and LLVM code generators

[GHC]

#5208: Unroll array copy/clone primops in the native and LLVM code generators
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    Reporter:  tibbe             |        Owner:              
        Type:  feature request   |       Status:  patch       
    Priority:  normal            |    Milestone:              
   Component:  Compiler          |      Version:  7.1         
    Keywords:                    |     Testcase:              
   Blockedby:                    |   Difficulty:              
          Os:  Unknown/Multiple  |     Blocking:              
Architecture:  Unknown/Multiple  |      Failure:  None/Unknown
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Comment(by dterei):

 So it looks fine, here are some comments though:

 '''0002-Unroll-memcpy-in-the-X86-backend.patch'''

  * '-- TODO: Add movabs instruction and support 64-bit sets.' - Can this
 be done now rather than later? It doesn't seem like it should take very
 long. Also I think once you have this done you should be able to unify the
 go functions of memcpy and memset
  * By saying add the movabs instruction I assume you want to change the
 memset function to initially store the value to set into a register and
 then mov that register into each of the memory slots. With this change you
 could also have memset handle the case where the value to be set is an
 expression other than a literal.
  * Should 'maxInlineSizeThreshold' be shared rather than duplicated?

 '''0001-Use-the-new-memcpy-memmove-memset-MachOps.patch'''

 Looks fine but would it be worthwhile handling the alignment number in the
 'emitMemmoveCall', 'emitMemcpyCall' and 'emitMemsetCall' functions
 themselves rather than passing it in as argument?

 '''0001-Add-test-for-unrolling-memcpy-memset-in-the-x86-back.patch'''

 I think this testing method works well. I think you should test when the
 alignment is 8 though as well as 4. Also maybe try to cover a few more
 cases by using some different sizes and alignments. So create the arrays
 at size 71 but then test a few times using sizes say 64,65,66,67 and
 alignments 1,2,4,8. The unroll code is fairly tricky and so we want an
 extensive test case.

 I'll be happy to help out with any of these points when I have time. Other
 than extending the test case though I would be happy pushing it to head as
 it stands.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5208#comment:7>
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