mirror of
https://github.com/golang/go
synced 2024-10-14 11:53:56 +00:00
39986d28e4
[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> |
||
|---|---|---|
| .. | ||
| archive | ||
| arena | ||
| bufio | ||
| builtin | ||
| bytes | ||
| cmd | ||
| compress | ||
| container | ||
| context | ||
| crypto | ||
| database/sql | ||
| debug | ||
| embed | ||
| encoding | ||
| errors | ||
| expvar | ||
| flag | ||
| fmt | ||
| go | ||
| hash | ||
| html | ||
| image | ||
| index/suffixarray | ||
| internal | ||
| io | ||
| log | ||
| maps | ||
| math | ||
| mime | ||
| net | ||
| os | ||
| path | ||
| plugin | ||
| reflect | ||
| regexp | ||
| runtime | ||
| slices | ||
| sort | ||
| strconv | ||
| strings | ||
| sync | ||
| syscall | ||
| testdata | ||
| testing | ||
| text | ||
| time | ||
| unicode | ||
| unsafe | ||
| vendor | ||
| all.bash | ||
| all.bat | ||
| all.rc | ||
| bootstrap.bash | ||
| buildall.bash | ||
| clean.bash | ||
| clean.bat | ||
| clean.rc | ||
| cmp.bash | ||
| go.mod | ||
| go.sum | ||
| make.bash | ||
| make.bat | ||
| Make.dist | ||
| make.rc | ||
| race.bash | ||
| race.bat | ||
| README.vendor | ||
| run.bash | ||
| run.bat | ||
| run.rc | ||
Vendoring in std and cmd
========================
The Go command maintains copies of external packages needed by the
standard library in the src/vendor and src/cmd/vendor directories.
There are two modules, std and cmd, defined in src/go.mod and
src/cmd/go.mod. When a package outside std or cmd is imported
by a package inside std or cmd, the import path is interpreted
as if it had a "vendor/" prefix. For example, within "crypto/tls",
an import of "golang.org/x/crypto/cryptobyte" resolves to
"vendor/golang.org/x/crypto/cryptobyte". When a package with the
same path is imported from a package outside std or cmd, it will
be resolved normally. Consequently, a binary may be built with two
copies of a package at different versions if the package is
imported normally and vendored by the standard library.
Vendored packages are internally renamed with a "vendor/" prefix
to preserve the invariant that all packages have distinct paths.
This is necessary to avoid compiler and linker conflicts. Adding
a "vendor/" prefix also maintains the invariant that standard
library packages begin with a dotless path element.
The module requirements of std and cmd do not influence version
selection in other modules. They are only considered when running
module commands like 'go get' and 'go mod vendor' from a directory
in GOROOT/src.
Maintaining vendor directories
==============================
Before updating vendor directories, ensure that module mode is enabled.
Make sure that GO111MODULE is not set in the environment, or that it is
set to 'on' or 'auto'.
Requirements may be added, updated, and removed with 'go get'.
The vendor directory may be updated with 'go mod vendor'.
A typical sequence might be:
cd src
go get golang.org/x/net@latest
go mod tidy
go mod vendor
Use caution when passing '-u' to 'go get'. The '-u' flag updates
modules providing all transitively imported packages, not only
the module providing the target package.
Note that 'go mod vendor' only copies packages that are transitively
imported by packages in the current module. If a new package is needed,
it should be imported before running 'go mod vendor'.