Now that we use LLVM 9, RISC-V support in LLVM has far fewer bugs and we
can avoid the GNU toolchain.
* replace GNU linker with lld
* replace GCC with clang
Additionally, RISC-V was promoted to stable so it can be enabled by
default in CI.
The .sdata and .sbss sections are created by the compiler, but were not
present in the linker script. That means that the linker put them after
all other data/bss section, which happens to be where the heap also
resides.
This commit adds the .sdata and .sbss sections to the linker script,
which gets the blinky examples to work again on RISC-V.
In my excitement to get the SoftDevice PR ready, I made two mistakes.
They're fixed in this commit.
* Add the `s132v6` build tag.
* Remove the (old) `ldscript` property.
This fixes the following issue:
https://github.com/aykevl/go-bluetooth/issues/1
This prevents it from being of type PROGBITS in lld 9, it should always
be NOBITS. It should fix the following error in lld 9:
ROM segments are non-contiguous
Setting the linker script as one property (instead of as part of the
generic ldflags property) allows it to be overriden.
This is important for the SoftDevice on Nordic chips, because the
SoftDevice takes up a fixed part of the flash/RAM and the application
must be flashed at a different position. With this linkerscript option,
it is possible to create (for example) a pca10040-s132v6 that overrides
the default linker script.
The name was cortex-m.s which looks like it is a generic assembly file
for all cortex-m targets. However, it really is only for qemu
simulation, because every chip has a slightly different interrupt vector
table.
This smartwatch doesn't have an on-board debugger, so I picked the one I
was using while getting this smartwatch to run Go programs (the J-Link
EDU Mini).
Instead of specifying explicit commands, most of these commands have
been replaced by more specific properties.
This is work that will be necessary for an eventual -programmer flag to
the compiler, with which it is possible to select which programmer to
use to flash or debug a chip. That's not very useful for boards that
already include a programmer or bootloader for that purpose, but is very
useful for novel boards or single-purpose boards that are not already
included in TinyGo.
Compared to the already supported stm32f103xx "bluepill" board this:
- features 128 KiB flash memory size ("RB" suffix) instead of 64 KiB, see `targets/stm32f103rb.ld`
- has onboard ST-LINK/V2-1 programmer and debugger requiring different OpenOCD configuration file
- uses USART2 connected to ST-LINK/V2-1 debugger as virtual COM port over USB for `putchar()`
- has a user-accessible button besides the reset button
This scheduler is intended to live along the (stackless) coroutine based
scheduler which is needed for WebAssembly and unsupported platforms. The
stack based scheduler is somewhat simpler in implementation as it does
not require full program transform passes and supports things like
function pointers and interface methods out of the box with no changes.
Code size is reduced in most cases, even in the case where no scheduler
scheduler is used at all. I'm not exactly sure why but these changes
likely allowed some further optimizations somewhere. Even RAM is
slightly reduced, perhaps some global was elminated in the process as
well.
Strings are emitted in .rodata sections, which are not yet mentioned in the linker script.
I can't exactly explain why it didn't work before, as these sections should have been included in .bss and thus properly aligned, but it appears to work reliably.
This makes sure that a stack overflow will cause a "memory access out of
bounds" error instead of a corruption of a global variable.
Here is more background on a very similar stack overflow protection:
https://blog.japaric.io/stack-overflow-protection/
dumb -> leaking:
make it more clear what this "GC" does: leak everything.
marksweep -> conservative:
"marksweep" is too generic, use "conservative" to differentiate
between future garbage collectors: precise marksweep / mark-compact /
refcounting.
This is very useful for debugging. It differentiates between a stack
overflow and other errors (because it's easy to see when a stack
overflow occurs) and prints the old stack pointer and program counter if
available.
This commit avoids setting the working directory to the TinyGo root when
invocating Clang. This helps to weed out issues before we add support
for bundling Clang in a release.
LLD version 8 has added support for armv6m:
https://reviews.llvm.org/D55555
This means we can use LLD instead of arm-none-eabi-ld, eliminating our
dependency on GNU binutils.
There are small differences in code size, but never more than a few
bytes.
This commit does a few things:
* remove the -8 suffix on macOS, where it is not necessary
* add smoke tests for compiling wasm files on Linux and macOS
So far, we've pretended to be js/wasm in baremetal targets to make the
stdlib happy. Unfortunately, this has various problems because
syscall/js (a dependency of many stdlib packages) thinks it can do JS
calls, and emulating them gets quite hard with all changes to the
syscall/js packages in Go 1.12.
This commit does a few things:
* It lets baremetal targets pretend to be linux/arm instead of
js/wasm.
* It lets the loader only select particular packages from the src
overlay, instead of inserting them just before GOROOT. This makes it
possible to pick which packages to overlay for a given target.
* It adds a baremetal-only syscall package that stubs out almost all
syscalls.
The wasm_exec.js file copied from the main Go repository did write those
values to address 4096 in linear memory, which led to memory corruption
in linear memory. Remove these things for now, until they're actually
supported, if support is ever added.
Unfortunately, the olin/cwa emulator does not handle floats correctly.
Node.js does, and because it is also supported by the Go WebAssembly
implementation it has better support in general.
When building statically against LLVM, LLD is also included now. When
included, the built in wasm-ld will automatically be used instead of the
external command.
There is also support for linking ELF files but because lld does not
fully support armv6m this is not yet enabled (it produces a warning).
