This patch is a combination of two related changes:
1. The compiler now allows other types than `int` when specifying the
size of a channel in a make(chan ..., size) call.
2. The compiler now checks for maximum allowed channel sizes. Such
checks are trivially optimized out in the vast majority of cases as
channel sizes are usually constant.
I discovered this issue when trying out channels on AVR.
The copy builtin is defined as follows by the Go language spec:
copy(dst, src []T) int
copy(dst []byte, src string) int
In other words, it returns an int. The runtime.sliceCopy compiler
intrinsic returned a uintptr instead, which led to a problem while
compiling the strings package for AVR.
No other architecture should be affected by this change as the
conversion from an uintptr to an int is a no-op on most architectures.
This allows TinyGo-built binaries to run under wasmtime, for example:
tinygo build -o test.wasm -no-debug -target=wasm examples/test
wasmtime run test.wasm 0
Thanks to Kyle Lemons for the inspiration and original design. The
implementation in this commit is very different however, building on top
of the software vectoring needed in RISC-V. The result is a flexible
interrupt handler that does not take up any RAM for configuration.
This is the same problem as in
https://github.com/tinygo-org/tinygo/pull/605, but other targets also
suffer from it.
Discovered with the GBA target, but as pointed out in
https://bugs.llvm.org/show_bug.cgi?id=42881#c1 this appears to be a bug
in the way external globals are declared, not in LLVM. Therefore I
decided that fixing it everywhere would be the best thing to do.
This commit adds support for software vectoring in the PLIC interrupt.
The interrupt table is created by the compiler, which leads to very
compact code while retaining the flexibility that the interrupt API
provides.
This might sound crazy, but I think it's better to enable the GC by
default to avoid surprises. It costs 1130 bytes of flash and 16 bytes of
RAM (plus heap overhead) so it's not exactly free, but if needed it can
easily be disabled with `-gc=leaking`. On the Uno (32kB flash, 2kB RAM)
that's not massive, on the DigiSpark (8kB flash, 0.5kB RAM) that may be
too much depending on the application.
This implementation simply casts types without special support to an
interface, to make the implementation simpler and possibly reducing the
code size too. It will likely be slower than the canonical Go
implementation though (which builds special compare and hash functions
at compile time).
This allows CGo code to call some libc functions. Additionally, by
putting memset/memmove/memcpy in an archive they're not included anymore
when not necessary, reducing code size for small programs.
This commit lets the compiler know about interrupts and allows
optimizations to be performed based on that: interrupts are eliminated
when they appear to be unused in a program. This is done with a new
pseudo-call (runtime/interrupt.New) that is treated specially by the
compiler.
This can be useful for debugging critical bugs in code. I haven't added
human-readable exceptions (such as "illegal instruction" or "stack
overflow") yet, they can be added when they happen in practice (to avoid
increasing code size too much).
This commit adds support for timer interrupts, replacing the busy loop
that was used before. It is perhaps the most simple interrupt to
implement and should serve as the basis for further interrupt support in
RISC-V.
The CLINT is implemented both on the fe310-g002 chip and in the sifive_e
QEMU machine type. Therefore, use that peripheral for consistency.
The only difference is the clock speed, which runs at 10MHz in QEMU for
some reason instead of 32.768kHz as on the physical HiFive1 boards.
QEMU doesn't support the RTC peripheral yet so work around it for now.
This makes the following command work:
tinygo run -target=hifive1-qemu ./testdata/coroutines.go
These all-caps constants aren't in the Go style, so rename it to
CPUFrequency (which is more aligned with Go style). Additionally, make
it a function so that it is possible to add support for changing the
frequency in the future.
Tested by running `make smoketest`. None of the outputs did change.
The Cortex-M architecture contains two stack pointers, designed to be
used by RTOSes: MSP and PSP (where MSP is the default at reset). In
fact, the ARM documentation recommends using the PSP for tasks in a
RTOS.
This commit switches to using the PSP for goroutine stacks. Aside from
being the recommended operation, this has the big advantage that the
NVIC automatically switches to the MSP when handling interrupts. This
avoids having to make every goroutine stack big enough that interrupts
can be handled on it.
Additionally, I've optimized the assembly code to save/restore registers
(made possible by this change). For Cortex-M3 and up, saving all
registers is just a single push instruction and restoring+branching is a
single pop instruction. For Cortex-M0 it's a bit more work because the
push/pop instructions there don't support most high registers.
Sidenote: the fact that you can pop a number of registers and branch at
the same time makes ARM not exactly a true RISC system. However, it's
very useful in this case.
This function adjusts the time returned by time.Now() and similar
functions. This is necessary on bare metal systems, where there would
not be a way to adjust the time otherwise.
* runtime/atsamd51: fix clock init code
The DPLL0 initialization should set LDRFRAC and LDR, not LDRFRAC twice.
Also explain what the magic numbers are doing.
An optimization introduced in a04db67ea9
seems to have broken arduino uno compiled hex. Setting optimzation
flags to 1, 2, or s builds proper hex binaries though.
These patches have been the result of troubleshooting over slack:
> @aykevl
> that preinit also doesn't look right. Can you try this variant,
> with 8-bit stores instead of 32-bit stores?
> There might be some alignment issue: the _ebss might not be
> aligned resulting in ptr != unsafe.Pointer(&_ebss) never being true.
Co-authored-by: Ayke van Laethem <aykevanlaethem@gmail.com>
Co-authored-by: Jaden Weiss <jadr2ddude@gmail.com>
