This commit switches from the previous behavior of compiling the whole
program at once, to compiling every package in parallel and linking the
LLVM bitcode files together for further whole-program optimization.
This is a small performance win, but it has several advantages in the
future:
- There are many more things that can be done per package in parallel,
avoiding the bottleneck at the end of the compiler phase. This
should speed up the compiler futher.
- This change is a necessary step towards a non-LTO build mode for
fast incremental builds that only rebuild the changed package, when
compiler speed is more important than binary size.
- This change refactors the compiler in such a way that it will be
easier to inspect the IR for one package only. Inspecting this IR
will be very helpful for compiler developers.
This package does not implement any methods, which is of course not
useful. However, by creating this package in advance it's possible to
see the next issue that's preventing something from building in TinyGo.
Motivated by: https://github.com/tinygo-org/tinygo/issues/1634
Since https://github.com/tinygo-org/tinygo/pull/1571 (in particular, the first
commit that sets the main package path), the main package is always named
"main". This makes the callMain() workaround in the runtime unnecessary and
allows directly calling the main.main function with a //go:linkname pragma.
On WebAssembly it is possible to grow the heap with the memory.grow
instruction. This commit implements this feature and with that also
removes the -heap-size flag that was reportedly broken (I haven't
verified that). This should make it easier to use TinyGo for
WebAssembly, where there was no good reason to use a fixed heap size.
This commit has no effect on baremetal targets with optimizations
enabled.
This commit swaps the layout of the heap. Previously, the metadata was
at the start and the data blocks (the actual heap memory) followed
after. This commit swaps those, so that the heap area starts with the
data blocks followed by the heap metadata.
This arrangement is not very relevant for baremetal targets that always
have all RAM allocated, but it is an important improvement for other
targets such as WebAssembly where growing the heap is possible but
starting with a small heap is a good idea. Because the metadata lives at
the end, and because the metadata does not contain pointers, it can
easily be moved. The data itself cannot be moved as the conservative GC
does not know all the pointer locations, plus moving the data could be
very expensive.
This commit changes the number of wait states for the stm32f103 chip to
2 instead of 4. This gets it back in line with the datasheet, but it
also has the side effect of breaking I2C. Therefore, another (seemingly
unrelated) change is needed: the i2cTimeout constant must be increased
to a higher value to adjust to the lower flash wait states - presumably
because the lower number of wait states allows the chip to run code
faster.
