Support //go:linkname compiler directive #1006
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The test exercises linknaming to a function in an importer package, as well as to a function from the importer package. The two cases are distinct because they have different package initialization order and must work both. Currently the test is passing under upstream Go, and panics under GopherJS.
These two types make an internal representation of a go:compile directive.
The implementation roughly follows these steps:
- compiler.Compile() gathers all information about go:linkname
directives in the source code and does basic correctness checks.
- compiler.WritePkgCode() uses this information to generate code
that exposes referenced function implementations in the `$linknames`
object, which serves as a global registry of sorts.
- It also generates code that will "import" those implementations
into appropriate packages from `$linknames` one all packages have
been defined. This code needs to be delayed because it may be
referencing packages which entries in `$packages` object have not
been populated yet.
This implementation is sufficient to pass our basic test case:
```
$ gopherjs build github.com/gopherjs/gopherjs/tests/testdata/linkname 148 ↵
$ node linkname.js
doing one
doing two
doing imported one: doing internal one: one secret
doing three
doing imported three: doing internal three: three secret
```
However, a few adjustments to the standard library overlays are still
needed to make it run correctly again.
Now that we support go:linkname directive, the time package expects to find this function implementation in the `runtime` package.
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@visualfc, you might be interested in taking a look at this PR. I've noticed that your implementation seems to go into infinite recursion when I build the test case from this PR with it. Here's an example stack trace (under Ubuntu, with a limit of 2G of virtual memory to prevent my laptop from going into swapping): Note that I built the gopherjs binary from your repository at goplusjs/gopherjs@0e65aed, but ran it this repository with this PR checked out. Hope that helps :) |
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Good idea, although I've created a separate document for compiler directives. |
This was causing a TestNativesDontImportExtraPackages test failure.
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goplusjs/gopherjs#35 this PR support go:linkname circle import |
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GopherJS implementation is a bit more limited that the upsteam's, but should be sufficient for our use cases. The main limitations are:
Fixes #1000.