This commit adds a new transform that converts reflect Implements()
calls to runtime.interfaceImplements. At the moment, the Implements()
method is not yet implemented (how ironic) but if the value passed to
Implements is known at compile time the method call can be optimized to
runtime.interfaceImplements to make it a regular interface assert.
This commit is the last change necessary to add basic support for the
encoding/json package. The json package is certainly not yet fully
supported, but some trivial objects can be converted to JSON.
This is important as golden test output and to verify that the output is
correct. Later improvements and bug fixes are clearly visible in the IR,
and unintentional changes will also be immediately spotted.
They both reversed the direction of the check, in a way that mostly
cancelled each other out. Of course they're still mostly unimplemented,
but it's better if they're not wrong.
This patch fixes a use of the global context. I've seen a few instances
of crashes in the llvm.ConstInt function when called from
makeStructTypeFields, which I believe are caused by this bug.
This fixes a type system loophole. The following program would
incorrectly run in TinyGo, while it would trigger a panic in Go:
package main
import "reflect"
func main() {
v := reflect.ValueOf(struct {
x int
}{})
x := v.Field(0).Interface()
println("x:", x.(int))
}
Playground link: https://play.golang.org/p/nvvA18XFqFC
The panic in Go is the following:
panic: reflect.Value.Interface: cannot return value obtained from unexported field or method
I've shortened it in TinyGo to save a little bit of space.
These stub functions are necessary for the encoding/json package. They
don't seem to be called in trivial cases, so leave them as simple stubs
for now.
This matches the main Go implementation and (among others) fixes a
compatibility issue with the encoding/json package. The encoding/json
package compares reflect.Type variables against nil, which does not work
as long as reflect.Type is of integer type.
This also adds a reflect.RawType() function (like reflect.Type()) that
makes it easier to avoid working with interfaces in the runtime package.
It is internal only, but exported to let the runtime package use it.
This change introduces a small code size increase when working with the
reflect package, but I've tried to keep it to a minimum. Most programs
that don't make extensive use of the reflect package (and don't use
package like fmt) should not be impacted by this.
This is necessary so that when reflect.Type is converted from a concrete
type to an interface type, the errors package can still be interpreted.
Without this change, basically every program would grow in size by a few
bytes.
The errors package has a call like this in the package initializer. This
commit adds support for running it at compile time, avoiding the call at
runtime.
This doesn't always help (the call is already optimized away in many
small programs) but it does help to shave off some binary size in larger
programs. Perhaps more importantly, it will avoid a penalty in code size
when the reflect package will convert reflect.Type from a regular type
to an interface type.
Previously there was code to avoid impossible type asserts but it wasn't
great and in fact was too aggressive when combined with reflection.
This commit improves this by checking all types that exist in the
program that may appear in an interface (even struct fields and the
like) but without creating runtime.typecodeID objects with the type
assert. This has two advantages:
* As mentioned, it optimizes impossible type asserts away.
* It allows methods on types that were only asserted on (in
runtime.typeAssert) but never used in an interface to be optimized
away using GlobalDCE. This may have a cascading effect so that other
parts of the code can be further optimized.
This sometimes massively improves code size and mostly negates the code
size regression of the previous commit.
This distinction was useful before when reflect wasn't properly
supported. Back then it made sense to only include method sets that were
actually used in an interface. But now that it is possible to get to
other values (for example, by extracting fields from structs) and it is
possible to turn them back into interfaces, it is necessary to preserve
all method sets that can possibly be used in the program in a type
assert, interface assert or interface method call.
In the future, this logic will need to be revisited again when
reflect.New or reflect.Zero gets implemented.
Code size increases a bit in some cases, but usually in a very limited
way (except for one outlier in the drivers smoke tests). The next commit
will improve the situation significantly.
Previously we used the --export-all linker flag to export most
functions. However, this is not needed and possibly increases binary
size. Instead, we should be exporting the specific functions to be
exported.
An allocated object is never nil, so there is no need for a nil check.
This probably does not result in any better optimization (the nil check
is easily optimized away by LLVM because the result of runtime.alloc is
marked nonnull) but it makes the slice tests a bit cleaner.
It's difficult to create clean test cases while remaining compatible
with multiple LLVM versions. Most test outputs are much more readable
after an instcombine pass but instcombine rules change between LLVM
versions, leading to different (but semantically equivalent) test
outputs.
This reduces the test coverage a little bit (because old LLVM versions
aren't tested as well), but it als makes it easier to add more complex
tests.
In the future it might be a good idea to make the compiler output a bit
less messy so these workarounds are not needed.
This commit switches from the previous behavior of compiling the whole
program at once, to compiling every package in parallel and linking the
LLVM bitcode files together for further whole-program optimization.
This is a small performance win, but it has several advantages in the
future:
- There are many more things that can be done per package in parallel,
avoiding the bottleneck at the end of the compiler phase. This
should speed up the compiler futher.
- This change is a necessary step towards a non-LTO build mode for
fast incremental builds that only rebuild the changed package, when
compiler speed is more important than binary size.
- This change refactors the compiler in such a way that it will be
easier to inspect the IR for one package only. Inspecting this IR
will be very helpful for compiler developers.
The SimpleDCE pass was previously used to only compile the parts of the
program that were in use. However, lately the only real purpose has been
to speed up the compiler a bit by only compiling the necessary
functions.
This pass however is a problem for compiling (and caching) packages in
parallel. Therefore, this commit removes it as a preparatory step
towards that goal.
This is a leftover from a long time ago, when everything was still in
the global context. The fact that this uses the global context is most
certainly a bug.
I have seen occasional crashes in the build-packages-indepedently branch
(and PRs based on it) which I suspect are caused by this bug. I think
this is a long-dormant bug that only surfaced when doing the compilation
steps in parallel.
This optimization level wasn't working before because some passes expect
some globals to be cleaned up afterwards. Cleaning these globals is
easy, just add the pass necessary for it. This shouldn't reduce the
usefulness of the -opt=0 build flag as most optimizations are still
skipped.
GetElementPtr would not work on values that weren't pointers. Because
fixed addresses (often used in memory-mapped I/O) are integers rather
than pointers in interp, it would return an error.
This resulted in the teensy40 target not compiling correctly since the
interp package rewrite. This commit should fix that.
This is an addition that landed in Go 1.12 but we couldn't use before
because we were supporting Go back until Go 1.11. It simplifies the code
around processes a bit.
This package does not implement any methods, which is of course not
useful. However, by creating this package in advance it's possible to
see the next issue that's preventing something from building in TinyGo.
Motivated by: https://github.com/tinygo-org/tinygo/issues/1634
