I see expressif released a fork of llvm with a new target: extensa.
This allows you to write code for esp8266 and esp32 using clang [1]

I wonder if we can use ldc (using -betterC I guess) to build code for these platforms as well.

Any idea?

[1] https://esp32.com/viewtopic.php?t=9226&p=38466

On Tuesday, 19 November 2019 at 12:51:06 UTC, Andrea Fontana wrote:
> I see expressif released a fork of llvm with a new target: extensa.
> This allows you to write code for esp8266 and esp32 using clang [1]
>
> I wonder if we can use ldc (using -betterC I guess) to build code for these platforms as well.
>
> Any idea?
>
> [1] https://esp32.com/viewtopic.php?t=9226&p=38466

A guy has already been experimenting with it: https://forum.dlang.org/post/slopmwagueijibteaihu@forum.dlang.org

On Tuesday, 19 November 2019 at 12:51:06 UTC, Andrea Fontana wrote:
> I see expressif released a fork of llvm with a new target: extensa.
> This allows you to write code for esp8266 and esp32 using clang [1]
>
> I wonder if we can use ldc (using -betterC I guess) to build code for these platforms as well.
>
> Any idea?
>
> [1] https://esp32.com/viewtopic.php?t=9226&p=38466

I think it's enough to generate llvm ir with the "-output-ll -betterC" flags, then the generated file can easily be compiled from llc of llvm extensa

On Tuesday, 19 November 2019 at 12:51:06 UTC, Andrea Fontana wrote:
> I see expressif released a fork of llvm with a new target: extensa.
> This allows you to write code for esp8266 and esp32 using clang [1]
>
> I wonder if we can use ldc (using -betterC I guess) to build code for these platforms as well.
>
> Any idea?
>
> [1] https://esp32.com/viewtopic.php?t=9226&p=38466

the toolchain building commands:

1. get the llvm and clang source for xtensa

  git clone https://github.com/espressif/llvm-xtensa.git
  git clone https://github.com/espressif/clang-xtensa.git llvm-xtensa/tools/clang

2. build llvm-clang for xtensa

    mkdir llvm_build
    cd llvm_build

    # from https://gist.github.com/MabezDev/26e175790f84f2f2b0f9bca4e63275d1
    cmake ../llvm-xtensa -DLLVM_TARGETS_TO_BUILD="Xtensa" -DCMAKE_BUILD_TYPE=Release -G "Ninja" -D CMAKE_INSTALL_PREFIX=/opt/llvm-xtensa

    # Take a while
    cmake --build . OR ninja
    ninja install

3. build ldc2 from source using above llvm

    get ldc source, I just used ldc-1.19.0-beta1-src.tar.gz

    mkdir build-ldc

    cmake -G Ninja ../ldc_source_dir -DCMAKE_BUILD_TYPE=Release -D CMAKE_INSTALL_PREFIX=/opt/ldc-xtensa -DLLVM_ROOT_DIR=/opt/llvm-xtensa
    ninja ldc2

And you may experience this:

```
 Linking CXX executable bin/ldc2
FAILED: bin/ldc2
: && /usr/bin/c++  -DDMDV2 -DHAVE_SC_ARG_MAX -O3 -DNDEBUG  -rdynamic obj/ldc2.o  -o bin/ldc2  lib/libldc.a -lLLVMWindowsManifest -lLLVMMCDisassembler -lLLVMLTO -lLLVMPasses -lLLVMObjCARCOpts -lLLVMLibDriver -lLLVMOption -lLLVMipo -lLLVMInstrumentation -lLLVMVectorize -lLLVMLinker -lLLVMIRReader -lLLVMDebugInfoPDB -lLLVMDebugInfoDWARF -lLLVMAsmParser -lLLVMXtensaCodeGen -lLLVMSelectionDAG -lLLVMAsmPrinter -lLLVMDebugInfoCodeView -lLLVMDebugInfoMSF -lLLVMCodeGen -lLLVMScalarOpts -lLLVMInstCombine -lLLVMTransformUtils -lLLVMBitWriter -lLLVMXtensaAsmParser -lLLVMXtensaDesc -lLLVMXtensaInfo -lLLVMTarget -lLLVMAnalysis -lLLVMProfileData -lLLVMObject -lLLVMMCParser -lLLVMBitReader -lLLVMCore -lLLVMBinaryFormat -lLLVMXtensaAsmPrinter -lLLVMMC -lLLVMSupport -lLLVMDemangle -L/opt/llvm-xtensa/lib -lz -lrt -ldl -ltinfo -lpthread -lm -lxml2 -Wl,--export-dynamic -fuse-ld=gold -L/usr/lib -lphobos2-ldc-shared -ldruntime-ldc-shared -Wl,-rpath,/usr/lib -Wl,--gc-sections -lrt -ldl -lpthread -lm -m64 -ldl -ltinfo -lpthread -lm -lxml2 && :
lib/libldc.a(main.cpp.o):main.cpp:function cppmain(): error: undefined reference to 'llvm::initializeGlobalISel(llvm::PassRegistry&)'
collect2: error: ld returned 1 exit status
ninja: build stopped: subcommand failed.
```

Edit build.ninja , search `build bin/ldc2:` and edit LINK_LIBRARIES  add `-lLLVMGlobalISel` before `-lLLVMCodeGen`
and `ninja ldc2` again.

Then we got ldc2 for xtensa in build-ldc/bin

4. test

vim test.d

void d_func ()
{
        int[4] arr;
        auto c = arr.length;
}

```
build-ldc2/bin/ldc2 -mtriple=xtensa-esp32-elf -mcpu=esp32 -gcc=xtensa-esp32-elf-gcc -betterC -dip1000 -boundscheck=off -linkonce-templates test.d -c

$ file test.o
test.o: ELF 32-bit LSB relocatable, Tensilica Xtensa, version 1 (SYSV), not stripped

$ readelf -s  test.o

Symbol table '.symtab' contains 4 entries:
   Num:    Value  Size Type    Bind   Vis      Ndx Name
     0: 00000000     0 NOTYPE  LOCAL  DEFAULT  UND
     1: 00000000     0 FILE    LOCAL  DEFAULT  ABS test.d
     2: 00000000     0 SECTION LOCAL  DEFAULT    4
     3: 00000000    24 FUNC    GLOBAL DEFAULT    4 _D4test6d_funcFZv
```

You can put the long compiler command into a shell script:

```
$ cat xtensa-ldc
#!/bin/sh

export PATH=${HOME}/esp/xtensa-esp32-elf-5/bin:${PATH}
build-ldc/bin/ldc2 -mtriple=xtensa-esp32-elf -mcpu=esp32 -gcc=xtensa-esp32-elf-gcc -betterC -dip1000 -boundscheck=off -linkonce-templates $@

5. integrate with IDF as a component

create a component called `dcode`, and write this style of makefile:

```
$ cat component.mk

    $(COMPONENT_LIBRARY):dcode.a

    SRC := $(wildcard $(COMPONENT_PATH)/*.d)
    COMOBJS := $(patsubst %.d, %.o, $(SRC))

    %.o : %.d
        ldc2-xtensa -c $< -of=$@

    COMPONENT_ADD_LDFLAGS += $(COMPONENT_BUILD_DIR)/dcodelib.a

    dcodelib :
        xtensa-esp32-elf-ar rc $(COMPONENT_BUILD_DIR)/dcodelib.a $(COMOBJS)

    dcode.a: $(SRC) $(COMOBJS) dcodelib
```

And you will have betterC d code compiles and linking:

```
$ cat dcode.d

module dcode;

extern(C) int printf (scope const char * fmt, ...);

char[8] a = ['a'];

extern (C) void dlang_main()
{
    uint i = 0;


    printf("hello, dlang says : i = %d, char a len = %d\r\n", i, a.length);
}

On Tuesday, 26 November 2019 at 04:34:44 UTC, dangbinghoo wrote:
> On Tuesday, 19 November 2019 at 12:51:06 UTC, Andrea Fontana wrote:
>> I see expressif released a fork of llvm with a new target: extensa.
>> This allows you to write code for esp8266 and esp32 using clang [1]
>>
>> I wonder if we can use ldc (using -betterC I guess) to build code for these platforms as well.
>>
>
> And you will have betterC d code compiles and linking:
>
> ```
> $ cat dcode.d
>
> module dcode;
>
> extern(C) int printf (scope const char * fmt, ...);
>
> char[8] a = ['a'];
>
> extern (C) void dlang_main()
> {
>     uint i = 0;
>
>
>     printf("hello, dlang says : i = %d, char a len = %d\r\n", i, a.length);
> }

PS: and in other place of you esp32 IDF C code, just call dlang_main as a pain c function, you will probably see Dlang is saying hello.

^_^

Hope these helps!

Thanks!

----
Binghoo Dang

On Tuesday, 26 November 2019 at 04:38:17 UTC, dangbinghoo wrote:
> On Tuesday, 26 November 2019 at 04:34:44 UTC, dangbinghoo wrote:
>> On Tuesday, 19 November 2019 at 12:51:06 UTC, Andrea Fontana wrote:
>>> I see expressif released a fork of llvm with a new target: extensa.
>>> This allows you to write code for esp8266 and esp32 using clang [1]
>>>
>>> I wonder if we can use ldc (using -betterC I guess) to build code for these platforms as well.
>>>
>>
>> And you will have betterC d code compiles and linking:
>>
>> ```
>> $ cat dcode.d
>>
>> module dcode;
>>
>> extern(C) int printf (scope const char * fmt, ...);
>>
>> char[8] a = ['a'];
>>
>> extern (C) void dlang_main()
>> {
>>     uint i = 0;
>>
>>
>>     printf("hello, dlang says : i = %d, char a len = %d\r\n", i, a.length);
>> }
>
> PS: and in other place of you esp32 IDF C code, just call dlang_main as a pain c function, you will probably see Dlang is saying hello.
>
> ^_^
>
> Hope these helps!
>
> Thanks!
>
> ----
> Binghoo Dang

Thank you very much for your fantastic work! I did your instructions on WSL Debian but had to change the build configuration for llvm-xtensa according to the link you posted

cmake ../llvm-xtensa -DLLVM_TARGETS_TO_BUILD="Xtensa;X86" -DCMAKE_BUILD_TYPE=Release -G "Ninja" -DCMAKE_INSTALL_PREFIX=/opt/llvm-xtensa

without the X86 build target llvm-config complains about a missing X86disassembler component. I am currently working on a template project for ESP-IDF with D support that makes compilation very easy and includes instructions/scripts to get it working, you saved me from a lot of work :)

On Tuesday, 26 November 2019 at 12:17:51 UTC, Paul Freund wrote:
> without the X86 build target llvm-config complains about a missing X86disassembler component. I am currently working on a template project for ESP-IDF with D support that makes compilation very easy and includes instructions/scripts to get it working, you saved me from a lot of work :)

you're welcome.

the makefile I posted should work making the D code building as a common C component.

---
Binghoo dang

On Tuesday, 26 November 2019 at 13:28:13 UTC, dangbinghoo wrote:
> On Tuesday, 26 November 2019 at 12:17:51 UTC, Paul Freund wrote:
>> without the X86 build target llvm-config complains about a missing X86disassembler component. I am currently working on a template project for ESP-IDF with D support that makes compilation very easy and includes instructions/scripts to get it working, you saved me from a lot of work :)
>
> you're welcome.
>
> the makefile I posted should work making the D code building as a common C component.
>
> ---
> Binghoo dang

It is still very unpolished but here https://github.com/PaulFreund/ESP32_Dlang_Template is a project template that should include all required steps to take to get your minimal D example running on a real ESP32 (tested, works!) based on either Debian or Windows Subsystem for Linux - Debian. I definitely want to include support for CMake compilation and a few other goodies.

On Wednesday, 27 November 2019 at 09:10:10 UTC, Paul Freund wrote:
> On Tuesday, 26 November 2019 at 13:28:13 UTC, dangbinghoo wrote:
>> On Tuesday, 26 November 2019 at 12:17:51 UTC, Paul Freund

> It is still very unpolished but here https://github.com/PaulFreund/ESP32_Dlang_Template is a project template that should include all required steps to take to get your minimal D example running on a real ESP32 (tested, works!) based on either Debian or Windows Subsystem for Linux - Debian. I definitely want to include support for CMake compilation and a few other goodies.

That's great!

maybe the dcode component makefile needs some tweak, the makefile I posted has a little problem: the D code compiled object was placed in the some dir with D sources, should be fixed.


---
binghoo dang