[This is a roll-forward of CL 479095, which was reverted due to a bad
interaction between inlining and escape analysis since fixed in CL 482355.]
Currently, when the inliner is determining if a function is
inlineable, it descends into the bodies of closures constructed by
that function. This has several unfortunate consequences:
- If the closure contains a disallowed operation (e.g., a defer), then
the outer function can't be inlined. It makes sense that the
*closure* can't be inlined in this case, but it doesn't make sense
to punish the function that constructs the closure.
- The hairiness of the closure counts against the inlining budget of
the outer function. Since we currently copy the closure body when
inlining the outer function, this makes sense from the perspective
of export data size and binary size, but ultimately doesn't make
much sense from the perspective of what should be inlineable.
- Since the inliner walks into every closure created by an outer
function in addition to starting a walk at every closure, this adds
an n^2 factor to inlinability analysis.
This CL simply drops this behavior.
In std, this makes 57 more functions inlinable, and disallows inlining
for 10 (due to the basic instability of our bottom-up inlining
approach), for an net increase of 47 inlinable functions (+0.6%).
This will help significantly with the performance of the functions to
be added for #56102, which have a somewhat complicated nesting of
closures with a performance-critical fast path.
The downside of this seems to be a potential increase in export data
and text size, but the practical impact of this seems to be
negligible:
│ before │ after │
│ bytes │ bytes vs base │
Go/binary 15.12Mi ± 0% 15.14Mi ± 0% +0.16% (n=1)
Go/text 5.220Mi ± 0% 5.237Mi ± 0% +0.32% (n=1)
Compile/binary 22.92Mi ± 0% 22.94Mi ± 0% +0.07% (n=1)
Compile/text 8.428Mi ± 0% 8.435Mi ± 0% +0.08% (n=1)
Updates #56102.
Change-Id: I1f4fc96c71609c8feb59fecdb92b69ba7e3b5b41
Reviewed-on: https://go-review.googlesource.com/c/go/+/482356
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Than McIntosh <thanm@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
The test directory contains tests of the Go tool chain and runtime.
It includes black box tests, regression tests, and error output tests.
They are run as part of all.bash.
To run just these tests, execute:
../bin/go test internal/testdir
To run just tests from specified files in this directory, execute:
../bin/go test internal/testdir -run='Test/(file1.go|file2.go|...)'
Standard library tests should be written as regular Go tests in the appropriate package.
The tool chain and runtime also have regular Go tests in their packages.
The main reasons to add a new test to this directory are:
it is most naturally expressed using the test runner; or
it is also applicable to gccgo and other Go tool chains.
