This is a big commit that changes the way runtime type information is stored in
the binary. Instead of compressing it and storing it in a number of sidetables,
it is stored similar to how the Go compiler toolchain stores it (but still more
compactly).
This has a number of advantages:
* It is much easier to add new features to reflect support. They can simply
be added to these structs without requiring massive changes (especially in
the reflect lowering pass).
* It removes the reflect lowering pass, which was a large amount of hard to
understand and debug code.
* The reflect lowering pass also required merging all LLVM IR into one
module, which is terrible for performance especially when compiling large
amounts of code. See issue 2870 for details.
* It is (probably!) easier to reason about for the compiler.
The downside is that it increases code size a bit, especially when reflect is
involved. I hope to fix some of that in later patches.
This commit fixes two related issues:
1. CanInterface was unimplemented. It now uses the same check as is
used in Interface() itself.
This issue led to https://github.com/tinygo-org/tinygo/issues/3033
2. Allow making an interface out of a string char element.
Doing this in one commit (instead of two) because they are shown to be
correct with the same tests.
The implementation has been mostly copied from the Go reference
implementation with some small changes to fit TinyGo.
Source: 77a11c05d6/src/reflect/deepequal.go
In addition, this commit also contains the following:
- A set of tests copied from the Go reflect package.
- An increased stack size for the riscv-qemu and hifive1-qemu targets
(because they otherwise fail to run the tests). Because these
targets are only used for testing, this seems fine to me.
In the case where:
- Value.Index() was called on an array
- that array was bigger than a pointer
- the element type fits in a pointer
- the 'indirect' flag isn't set
the Value.Index() method would still (incorrectly) load the value.
This commit fixes that.
The next commit adds a test which would have triggered this bug so works
as a regression test.
v.Interaface() could construct an interface in interface value if v was
of type interface. This is not correct, and doesn't follow upstream Go
behavior. Instead, it should return the interface value itself.
This layout parameter is currently always nil and ignored, but will
eventually contain a pointer to a memory layout.
This commit also adds module verification to the transform tests, as I
found out that it didn't (and therefore didn't initially catch all
bugs).
These variants uses an unsafe.Pointer instead of uintptr so that the
pointer/non-pointer fields match those of real slices and strings. This
may be necessary in the future once we switch to a precise garbage
collector.
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 replaces the custom runtime.memcpy and runtime.memmove functions
with calls to LLVM builtins that should hopefully allow LLVM to better
optimize such calls. They will be lowered to regular libc memcpy/memmove
when they can't be optimized away.
When testing this change with some smoke tests, I found that many smoke
tests resulted in slightly larger binary sizes with this commit applied.
I looked into it and it appears that machine.sendUSBPacket was not
inlined before while it is with this commit applied. Additionally, when
I compared all driver smoke tests with -opt=1 I saw that many were
reduced slightly in binary size and none increased in size.
This commit makes sure all Go types can be encoded in the interface type
code, so that Type.Kind() always returns a proper type kind for any
non-nil interface.
Package encoding/binary uses reflect and is needed by image/png, but
image/png doesn't actually need the reflect-using parts of
encoding/binary. So stub them out for now to get it to compile.
Thanks to Stephen Solka who wrote the patch.
