The Espressif fork of LLVM now has Xtensa support in the linker LLD.
(This support was written mosly by me). This means we don't have to use
the Espressif GNU toolchain anymore and makes installing TinyGo simpler.
In the future, this also paves the way for ThinLTO support. Right now it
is mostly just a way to simplify TinyGo installation and speed up CI
slightly.
Switch over to LLVM 14 for static builds. Keep using LLVM 13 for regular
builds for now.
This uses a branch of the upstream Espressif branch to fix an issue,
see: https://github.com/espressif/llvm-project/pull/59
This is for consistency with Clang, which always adds a CPU flag even if
it's not specified in CFLAGS.
This commit also adds some tests to make sure the Clang target-cpu
matches the CPU property in the JSON files.
This does have an effect on the generated binaries. The effect is very
small though: on average just 0.2% increase in binary size, apparently
because Cortex-M3 and Cortex-M4 are compiled a bit differently. However,
when rebased on top of https://github.com/tinygo-org/tinygo/pull/2218
(minsize), the difference drops to -0.1% (a slight decrease on average).
With this change, it is possible to fully use CGo on ESP32/ESP8266
chips. The following will work:
tinygo flash -target=d1mini -port=/dev/ttyUSB0 ./testdata/cgo/
tinygo flash -target=esp32-mini32 -port=/dev/ttyUSB0 ./testdata/cgo/
Previously it would produce output like the following:
/tmp/tinygo905539688/main.o:(.literal.runtime.run$1$gowrapper+0x150): undefined reference to `strcpy'
/tmp/tinygo905539688/main.o:(.literal.runtime.run$1$gowrapper+0x154): undefined reference to `strlen'
With this change, it is possible to compile ./testdata/float.go for the
ESP8266 and run it successfully. Previously it would result in many
linker error like this:
/tmp/tinygo494494333/main.o:(.literal.runtime.printfloat64+0x0): undefined reference to `__unorddf2'
/tmp/tinygo494494333/main.o:(.literal.runtime.printfloat64+0x4): undefined reference to `__gtdf2'
/tmp/tinygo494494333/main.o:(.literal.runtime.printfloat64+0xc): undefined reference to `__nedf2'
/tmp/tinygo494494333/main.o:(.literal.runtime.printfloat64+0x10): undefined reference to `__ltdf2'
/tmp/tinygo494494333/main.o:(.literal.runtime.printfloat64+0x1c): undefined reference to `__gedf2'
I have verified that the output on the serial console matches
./testdata/float.txt when run on the ESP8266.
I have chosed to call this implementation `esp8266` instead of `xtensa`
as it has been written specifically for the ESP8266 and there are no
other Xtensa chips with the CALL0 ABI (no windowing) that I know of. The
only other related chip is the ESP32, which does implement register
windowing and thus needs a very different implementation.
