Generalize "trivial call" flag to other simple instructions #7670
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A "trivial call" is a function that just calls another function.
(func $foo ...
(call $target ...))
Currently we inline these functions always only when not optimizing for
code size.
When optimizing for code size, these functions can always be inlined
when
1. The arguments to `$target` are all function argument locals.
2. The locals are not used more than once
3. The locals are used in the same order they appear in the function
arguments.
When these hold, inlining `$foo` never increases code size as it doesn't
cause introducing more locals at call sites.
Improve `FunctionInfo` type and `FunctionInfoScanner` to annotate
functions with "trivial call" information that also contains whether
inlining shrinks code size.
If a function shrinks when inlined always inline it even with `-Os`.
Otherwise inline it as before, i.e. when not optimizing for code size.
An option is to create a PR in your fork, and ping people there. That's what I usually do. (Then, after the parent branch lands in upstream, you need to create a new PR there, so there is a downside...) Though, perhaps it makes sense to focus on the first PR for now? |
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Note: this is based on #7669. I can't create a PR to that branch as the branch lives in my my fork.
I can merge this to #7669 if that's more helpful than a separate PR?
A "trivial call" function is a function that just calls another with
local.gets as arguments.These functions can sometimes be inlined when optimizing for size.
With this PR we generate "trivial call" flag to "trivial instruction", to cover binary instructions like
i32.addand unary instructions likei32.eqz.With this PR wasm-opt now inlines trivial functions in dart2wasm outputs like:
Note: dart2wasm doesn't directly generate these functions, these become "trivial" after wasm-opt passes.