[llvm-commits] [PATCH] Shrink MachineOperand from 40 to 32 bytes

[Jakob Stoklund Olesen]

Hi,

The attached patch shrinks MachineOperand from 40 to 32 bytes on 64-bit hosts.

The Contents union contains pointers, so it becomes 8-byte aligned. That creates padding because the largest member has two pointers and an unsigned.

The patch moves the unsigned outside the union in a way that makes it pack optimally on both 32-bit and 64-bit hosts.

It is a bit icky, so I wanted your opinions before committing.

I measured a (statistically significant) 0.8% speedup of code generation on 64-bit Darwin with the patch applied.

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