internal: hard code endianness #662
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This results in a reduction of the instructions necessary for endian-related operations. The wall clock time difference for a single call is miniscule (picoseconds). An example, with the ByteOrder.Uint32 function: Runtime instructions: https://godbolt.org/z/7vW1Pfnso Buildtime instructions: https://godbolt.org/z/baxW1Wb7W The function call on amd64 changes from: MOVQ "".NativeEndian(SB), CX MOVQ "".NativeEndian+8(SB), DX MOVQ 64(CX), CX MOVQ AX, BX MOVL $4, DI MOVQ DX, AX MOVQ CX, DX MOVQ DI, CX CALL DX to XCHGL AX, AX The difference on arm64 is equivalent, but uses different specific instructions.
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This results in a reduction of the instructions necessary for endian-related operations.
The wall clock time difference for a single call is miniscule (picoseconds).
An example, with the ByteOrder.Uint32 function:
Runtime instructions: https://godbolt.org/z/7vW1Pfnso
Buildtime instructions: https://godbolt.org/z/baxW1Wb7W
The function call on amd64 changes from:
to
The difference on arm64 is equivalent, but uses different specific instructions.