This means runtime.alloc isn't allocated every time but instead only
when it is actually needed. It also just cleans up the compiler code a
little bit, and makes the next commit a bit nicer.
Go 1.26 changed all Windows syscall wrappers in zsyscall_windows.go
to use SyscallN instead of fixed-argument Syscall/Syscall6/etc. The
SyscallN function now has a body that calls an unexported syscalln
function (provided by runtime via //go:linkname).
TinyGo's existing createSyscall compiler builtin used call.Args[2:]
to extract syscall arguments, but for variadic SyscallN the SSA
representation passes args as a slice value (not individual args),
causing call.Args[2:] to be empty -- resulting in zero arguments
being passed to Windows API calls and 0xc0000005 access violations.
Fix this by:
1. Excluding syscall.SyscallN from builtin interception, letting
Go 1.26's function body compile normally (it calls syscalln)
2. Adding a new createSyscalln compiler builtin that intercepts
syscall.syscalln and correctly handles the variadic slice:
- Generates a switch on the arg count n (0-18 cases)
- Each case loads args from the slice via GEP/Load
- Wraps calls with SetLastError(0)/GetLastError() as before
- Handles i386 stdcall conventions
3. Adding runtime stubs for both Go versions:
- go1.26: syscall.syscalln stub (body intercepted by compiler)
- pre-go1.26: syscall.SyscallN stub (linker satisfaction)
The compiler now implements the copy builtin directly instead of calling sliceCopy.
The length is calculated with the llvm.umax.* intrinsics, and the move is performed by llvm.memmove.*.
Both of these operations are easily understood by LLVM's optimization passes.
The type's alignment is also provided to llvm.memmove.*, which is useful when rewriting the move.
Interp no longer needs to reimplement sliceCopy.
Some edge case handling was implemented by sliceCopy but not llvm.memmove.*/llvm.memcpy.*.
I copied this over, so copies of external slices should work now.
Volatile moves/copies are now run at runtime by interp.
There is a 4-byte size increase due to some confusing length logic in sendUSBPacket.
I will look at sendUSBPacket in a future PR.
This fixes two edge cases for min/max:
min/max(+0.0, -0.0) = -0.0, +0.0
min/max(number, NaN) = NaN, NaN
The compare and select method does not work here.
I switched to the llvm.minimum/llvm.maximum intrinsics which match the intended behavior.
The integer min/max were also swapped over to using intrinsics.
The compare and select path is now only used by strings.
The compiler needs to know whether a defer is in a loop to determine whether to allocate stack or heap memory.
Previously, this performed a DFS of the CFG every time a defer was found.
This resulted in time complexity jointly proportional to the number of defers and the number of blocks in the function.
Now, the compiler will instead use Tarjan's strongly connected components algorithm to find cycles in linear time.
The search is performed lazily, so this has minimal performance impact on functions without defers.
In order to implement Tarjan's SCC algorithm, additional state needed to be attached to the blocks.
I chose to merge all of the per-block state into a single slice to simplify memory management.
This type can be used to jump back to a previous position in a program
from inside an interrupt. This is useful for baremetal systems that
implement wfi but not wfe, and therefore have no easy (race-free) way to
wait until a flag gets changed inside an interrupt. This is an issue on
RISC-V, where this is racy (the interrupt might happen after the check
but before the wfi instruction):
configureInterrupt()
for flag.Load() != 0 {
riscv.Asm("wfi")
}
This ensures that calls to print/println happening in different threads
are not interleaved. It's a task.PMutex, so this should only change
things when threading is used.
This matches the Go compiler, which does the same thing:
https://godbolt.org/z/na5KzE7en
The locks are not recursive, which means that we need to be careful to
not call `print` or `println` inside a runtime.print* implementation,
inside putchar (recursively), and inside signal handlers. Making them
recursive might be useful to do in the future, but it's not really
necessary.
Use a single package for certain constants that must be the same between
the compiler and the runtime.
While just using the same values in both places works, this is much more
obvious and harder to mess up. It also avoids the need for comments
pointing to the other location the constant is defined. And having it in
code makes it possible for IDEs to analyze the source.
In the future, more such constants and maybe algorithms can be added.
This adds support for the `//go:wasmexport` pragma as proposed here:
https://github.com/golang/go/issues/65199
It is currently implemented only for wasip1 and wasm-unknown, but it is
certainly possible to extend it to other targets like GOOS=js and
wasip2.
This required a few compiler and runtime tricks to work, but I ran a
bunch of tests and it seems fine. (CI will of course do more exhaustive
testing).
The main benefit here is that we don't need to maintain the darwin
version of the syscall package, and reduce extra risks for bugs (because
we reuse the well-tested syscall package). For example, Go 1.23 needed a
bunch of new constants in the syscall package. That would have been
avoided if we had used the native syscall package on MacOS.
TODO: Remove the go.mod/go.sum in internal/tools once doing so doesn't break CI (e.g. once we drop support for go 1.19)
* builder/cc1as.h: fix typo found by 'make spell'
* GNUmakefile: remove exception for inbetween, fix instance now found by 'make spell'
* GNUmakefile: remove exception for programmmer, fix instance now found by 'make spell'
* go.mod: use updated misspell. GNUmakefile: add spellfix target, use it.
* ignore directories properly when invoking spellchecker.
* make spell: give internal/tools its own go.mod, as misspell requires newer go
* make lint: depend on tools and run the installed revive
(which was perhaps implied by the change that added revive to internal/tools,
but not required in GNUmakefile until we gave internal/tools its own temporary go.mod)
* .github: now that 'make spell' works well, run it from CI
* GNUmakefile: make spell now aborts if it finds misspelt words, so what it finds doesn't get lost in CI logs
* GNUmakefile: tools: avoid -C option on go generate to make test-llvm15-go119 circleci job happy, see
https://cs.opensource.google/go/go/+/2af48cbb7d85e5fdc635e75b99f949010c607786
* internal/tools/go.mod: fix format of go version to leave out patchlevel, else go complains.
This adds something like 'align 4' to the runtime.alloc calls, so that
the compiler knows the alignment of the allocation and can optimize
accordingly.
The optimization is very small, only 0.01% in my small test. However, my
plan is to read the value in the heap-to-stack transform pass to make it
more correct and let it produce slightly more optimal code.
Support for `-panic=trap` was previously a pass in the optimization
pipeline. This change moves it to the compiler and runtime, which in my
opinion is a much better place.
As a side effect, it also fixes
https://github.com/tinygo-org/tinygo/issues/4161 by trapping inside
runtime.runtimePanicAt and not just runtime.runtimePanic.
This change also adds a test for the list of imported functions. This is
a more generic test where it's easy to add more tests for WebAssembly
file properties, such as exported functions.
This is a big change: apart from removing LLVM 14 it also removes typed
pointer support (which was only fully supported in LLVM up to version
14). This removes about 200 lines of code, but more importantly removes
a ton of special cases for LLVM 14.
This is a small change that's not really important in itself, but it
avoids duplicate errors in a future commit that adds error messages to
//go:wasmimport.
These functions can be implemented more efficiently using LLVM
intrinsics. That makes them the Go equivalent of functions like
__builtin_clz which are also implemented using these LLVM intrinsics.
I believe the Go compiler does something very similar: IIRC it converts
calls to these functions into optimal instructions for the given
architecture.
I tested these by running `tinygo test math/bits` after uncommenting the
tests that would always fail (the *PanicZero and *PanicOverflow tests).
It is possible to create function-local named types:
func foo() any {
type named int
return named(0)
}
This patch makes sure they don't alias with named types declared at the
package scope.
Bug originally found by Damian Gryski while working on reflect support.
Previously we only supported recursive types in structs. But there can
be other kinds of recursive types, like slices:
type RecursiveSlice []RecursiveSlice
This doesn't involve structs, so it led to infinite recursion in the
compiler. This fix avoids recursion at the proper level: at the place
where the named type is defined.
There was a mostly benign race condition in the compiler. The issue was
that there is a check for type aliases (which can alias types in another
function), but this check was _after_ accessing a property of the
function that might not have been completed.
I don't think this can have any serious effects, as the function is
skipped anyway, but such bugs should certainly be fixed.
If there is no source location, at least use the file (but not line) for
debug information.
This attributes almost 1kB of string data for ./testdata/stdlib.go when
compiling for WASI.
This is helpful for WebAssembly: it makes it possible to attribute many
more data to locations in the source code, which makes `-size=full` more
useful.
I have checked this conversion is not needed anymore after the previous
commit, by running various smoke tests of which none triggered this
optimization. The only case where the optimization would have kicked in
is in syscall/syscall_windows.go:76 of the Go standard library.
Therefore, I prefer to remove it to reduce code complexity.
This metadata is emitted by Clang and I found it is important for source
level debugging on MacOS. This patch does not get source level debugging
to work yet (for that, it seems like packages need to be built
separately), but it is a step in the right direction.
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.
Using ThinLTO manages to optimize binaries quite significantly. The
exact amount varies a lot by program but it's about 10-15% usually.
Don't remove non-ThinLTO support yet. It would not surprise me if this
triggered some unintended side effect. Eventually, non-ThinLTO support
should be removed though.
I found that when I enable ThinLTO, a miscompilation triggers that had
been hidden all the time previously. The bug appears to happen as
follows:
1. TinyGo generates a function with a runtime.trackPointer call, but
without an alloca (or the alloca gets optimized away).
2. LLVM sees that no alloca needs to be kept alive across the
runtime.trackPointer call, and therefore it adds the 'tail' flag.
One of the effects of this flag is that it makes it undefined
behavior to keep allocas alive across the call (which is still safe
at that point).
3. The GC lowering pass adds a stack slot alloca and converts
runtime.trackPointer calls into alloca stores.
The last step triggers the bug: the compiler inserts an alloca where
there was none before but that's not valid as long as the 'tail' flag is
present.
This patch fixes the bug in a somewhat dirty way, by always creating a
dummy alloca so that LLVM won't do the optimization in step 2 (and
possibly other optimizations that rely on there being no alloca
instruction).
Ayke van Laethem
deadprogram
Damian Gryski
Nia Waldvogel
dkegel-fastly
leongross
Elliott Sales de Andrade