Add Unsafe.CopyBlockUnaligned #18801

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1. benaadams commented on Sep 30, 2016

   

   benaadams

   on Sep 30, 2016

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   It will currently work with core clr but might not with other runtimes and may not work in future dotnet/coreclr#7198 (comment)

   ECMA-355 says:
   "cpblk assumes that both destaddr and srcaddr are aligned to the natural size of the machine (but see the unaligned. prefix instruction). The operation of the cpblk instruction can be altered by an immediately preceding volatile. or unaligned. prefix instruction.
2. jkotas commented on Oct 3, 2016

   

   jkotas

   on Oct 3, 2016

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   We should also add InitBlockUnaligned to make the surface symmetric. Looks good to me otherwise.
3. nietras commented on Oct 7, 2016

   

   nietras

   on Oct 7, 2016

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   I am looking at adding this. Would this be fine:

     .method public hidebysig static void CopyBlockUnaligned(void* destination, void* source, uint32 byteCount) cil managed aggressiveinlining
     {
           .custom instance void System.Runtime.Versioning.NonVersionableAttribute::.ctor() = ( 01 00 00 00 )
           .maxstack 3
           ldarg.0
           ldarg.1
           ldarg.2
           unaligned. 0x1
           cpblk
           ret
     } // end of method Unsafe::CopyBlockUnaligned
   

   and:

     .method public hidebysig static void InitBlockUnaligned(void* startAddress, uint8 'value', uint32 byteCount) cil managed aggressiveinlining
     {
           .custom instance void System.Runtime.Versioning.NonVersionableAttribute::.ctor() = ( 01 00 00 00 )
           .maxstack 3
           ldarg.0
           ldarg.1
           ldarg.2
           unaligned. 0x1
           initblk
           ret
     } // end of method Unsafe::InitBlockUnaligned
   

   any suggestions for tests?
4. nietras commented on Oct 7, 2016

   

   nietras

   on Oct 7, 2016

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   And what about the uint32 byteCount as far as I understand Span also need UIntPtr version, correct?
5. jkotas

   closed this as completedin corefx#12443on Oct 7, 2016
6. msftgits

   transferred this issue fromdotnet/corefxon Jan 31, 2020
7. msftgits

   added this to the 2.0.0 milestone on Jan 31, 2020
8. ghost locked as resolved and limited conversation to collaborators on Dec 28, 2020