[PATCH] D146216: [lld][ELF] Relax long jump/call to short jump/call on AVR

[Ben Shi via Phabricator via llvm-commits]

benshi001 added a comment.

In D146216#4225135 <https://reviews.llvm.org/D146216#4225135>, @MaskRay wrote:

> Replacing an instruction to two likely makes the execution slower, so I think since we don't implement linker relaxation for AVR, we should not do the jmp/call rewriting as well.

My change is measurable,

1. short jmp/call cost 1 less tick than long jmp/call
2. the nop costs 1 tick.

So the rewriting of call has neither improvement nor regression, since the nop is always executed, so there is no tick/space change.

But the rewriting of jmp does have improvement on time, since the nop is no longer executed, one tick can be saved.


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https://reviews.llvm.org/D146216