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proposal: cmd/compile: type layout optimization: apply struct field reordering during compile time for efficient memory alignment #53048

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Dentrax opened this issue May 24, 2022 · 1 comment
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@Dentrax
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@Dentrax Dentrax commented May 24, 2022

Context

The goal is to divorce the order of fields in source code from the order of struct fields, then optimize structs by always ordering fields from least to most aligned in memory layout. 1

Proposal

type Unoptimized struct {
  a int8
  b int16
  c int8
  ...
}

During compile time optimization phase, Go should try to optimize reordering for all structs and their fields.

type LetGoOptimize struct {
  a int8
  b int8
  c int16
  ...
}

golang.org/x/tools already have a linter called fieldalignment that detects structs that would use less memory if their fields were sorted.

Backward Compatibility

I don't have much technical detail about the compiler to cover this section. So waiting your thoughts!

  • New go:noreorder compiler directive

The //go:noreorder directive must be followed by a type struct declaration. It specifies that auto reordering should not be applied, overriding the compiler's usual optimization rules.

Similar Works

P.S: I couldn't find neither a similar proposal her nor discussions; so feel free to close and drop some references if this is duplicate or have discussed before.

Footnotes

  1. https://go101.org/article/memory-layout.html

@gopherbot gopherbot added this to the Proposal milestone May 24, 2022
@seankhliao
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@seankhliao seankhliao commented May 24, 2022

Duplicate of #36606

@seankhliao seankhliao marked this as a duplicate of #36606 May 24, 2022
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