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>
False positives (pointers that point to nowhere but happen to point into
the heap) would result in the block just before that pointer to be
marked. This is clearly not intended, so ignore such a pointer.
A bug was introduced in the previous commit that led to miscompilations
in the time.Sleep function when the scheduler was disabled, because
time.Sleep (implemented in the runtime) tried to switch to the scheduler
stack.
This commit restores the binary size of most examples to what it was
before, but still reduces static RAM consumption (.bss) slightly. This
gives me some confidence that it does indeed fix the introduced bug.
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.
Previously it would use a bitcast, which cannot directly be used on AVR
because functions live in a different address space on AVR. To fix this,
use a ptrtoint/inttoptr pair.
This allows testdata/coroutines.go to be compiled, but due to what
appears to be an LLVM bug cannot be optimized and codegen'ed:
tinygo: /home/ayke/src/github.com/tinygo-org/tinygo/llvm-project/llvm/lib/IR/Constants.cpp:1776: static llvm::Constant *llvm::ConstantExpr::getBitCast(llvm::Constant *, llvm::Type *, bool): Assertion `CastInst::castIsValid(Instruction::BitCast, C, DstTy) && "Invalid constantexpr bitcast!"' failed.
This happens as one of the function passes after the TinyGo passes and
after the module has been verified so most likely it is a bug somewhere
in LLVM.
This commit fixes the following issue:
https://github.com/tinygo-org/tinygo/issues/309
Also, it prepares for some other reflect-related changes that should
make it easier to add support for named types (etc.) in the future.
See the following bug: https://bugs.llvm.org/show_bug.cgi?id=42881
I think this is a bug in LLVM, but the code in question wasn't the best
code anyway. By fixing this, about 16 bytes of code are saved on ARM
chips (and much more on AVR).
In particular, add support for a few math intrinsics for WebAssembly,
but add a few intrinsics to other systems as well at the same time. Some
may be missing still but will be easy to add if needed.
This increases the performance of one example by 50% to 100% depending
on the browser: the bottleneck was the inefficient sqrt implementation.
When the target supports it, allow the (initial) heap size to be
configured. Currently only supported in WebAssembly.
This also changes the default heap size of WebAssembly from 64kB to 1MB.
This is directly useful to avoid some unsafety around runtime.alloc and
should be useful in general.
This pragma has the same form as in the main Go compiler:
https://github.com/golang/go/issues/12312
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.
