Calling errors.New in an error path causes a heap allocation at an
already unfortunate moment. It is more efficient to create these error
values in globals and return these constant globals. If these errors are
not used (because the related code was optimized out), the globals will
also be optimized out.
This is the kind that is used in Go (actually CGo) for exporting
functions. I think it's best to use //export instead of our custom
//go:export pragma, for consistency (they are equivalent in TinyGo).
Therefore I've updated all instances to the standard format (except for
two that are updated in https://github.com/tinygo-org/tinygo/pull/1024).
No smoke tests changed (when comparing the output hash), except for some
wasm tests that include DWARF debug info and tend to be flaky anyway.
Previously, the compiler used LLVM's shift instructions directly, which have UB whenever the shifts are large or negative.
This commit adds runtime checks for negative shifts, and handles oversized shifts.
This gives the optimizer a bit more information about what the calls do.
This should result in slightly better generated code.
Code size sometimes goes up and sometimes goes down. I blame the code
size going up on the inliner which inlines more functions, because
compiling the smoke tests in the drivers repository with -opt=1 results
in a slight code size reduction in all cases.
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.
Somehow moving to LLVM memory intrinsics for calls like memcpy made the
machine.sendUSBPacket get inlined. This is a problem because it is
called in many different functions and it is just big enough to cause a
significant file size increase.
Adding //go:noinline solves this problem and gets the examples/blinky1
program below the file size it was before this change (tested:
itsybitsy-m0, itsybitsy-m4, circuitplay-bluefruit).
This hack was originally introduced in
https://github.com/tinygo-org/tinygo/pull/251 to fix an escape analysis
regression after https://github.com/tinygo-org/tinygo/pull/222
introduced nil checks. Since a new optimization in LLVM (see
https://reviews.llvm.org/D60047) this hack is not necessary anymore and
can be removed.
I've compared all regular tests and smoke tests before and after to
check the size. In most cases this change was an improvement although
there are a few regressions.
This is necessary for better CGo support on bare metal. Existing
libraries expect to be able to include parts of libc and expect to be
able to link to those symbols.
Because with this all targets have a working libc, it is now possible to
add tests to check that a libc in fact works basically.
Not all parts of picolibc are included, such as the math or stdio parts.
These should be added later, when needed.
This commit also avoids the need for the custom memcpy/memset/memcmp
symbols that are sometimes emitted by LLVM. The C library will take care
of that.
This adds support for the `-scheduler=tasks` flag for AVR. On most AVR
chips you wouldn't want to run a real scheduler but it may be useful in
some cases, especially on devices with more RAM. It is disabled by
default.
Not tested on actual hardware, only on simavr. The main motivation for
adding this chip is to be able to run simulated tests using a much
larger memory space (16kB RAM, 128kB flash) without jumping to the XMega
devices that may not be as well supported by LLVM.
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.
