mirror of https://github.com/golang/go.git
04a9b16f3d
Broadly speaking, escape analysis has two main phases. First, it traverses the AST while building a data-flow graph of locations and edges. Second, during "solve", it repeatedly walks the data-flow graph while carefully propagating information about each location, including whether a location's address reaches the heap. Once escape analysis is in the solve phase and repeatedly walking the data-flow graph, almost all the information it needs is within the location graph, with a notable exception being the ir.Class of an ir.Name, which currently must be checked by following a pointer from the location to its ir.Node. For typical graphs, that does not matter much, but if the graph becomes large enough, cache misses in the inner solve loop start to matter more, and the class is checked many times in the inner loop. We therefore store the class information on the location in the graph to reduce how much memory we need to load in the inner loop. The package github.com/microsoft/typescript-go/internal/checker has many locations, and compilation currently spends most of its time in escape analysis. This CL gives roughly a 30% speedup for wall clock compilation time for the checker package: go1.24.0: 91.79s this CL: 64.98s Linux perf shows a healthy reduction for example in l2_request.miss and dTLB-load-misses on an amd64 test VM. We could tweak things a bit more, though initial review feedback has suggested it would be good to get this in as it stands. Subsequent CLs in this stack give larger improvements. Updates #72815 Change-Id: I3117430dff684c99e6da1e0d7763869873379238 Reviewed-on: https://go-review.googlesource.com/c/go/+/657295 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Keith Randall <khr@google.com> Reviewed-by: Jake Bailey <jacob.b.bailey@gmail.com> Reviewed-by: David Chase <drchase@google.com> |
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README.vendor
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', and if you use a go.work file, set GOWORK=off.
Also, ensure that 'go env GOROOT' shows the root of this Go source
tree. Otherwise, the results are undefined. It's recommended to build
Go from source and use that 'go' binary to update its source tree.
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 # or src/cmd
go get golang.org/x/net@master
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'.