LLVM support on all applicable architectures

[zephyrbot]

Reported by Anas Nashif:

Expand LLVM support to all architectures with LLVM toolchain

(Imported from Jira ZEP-2253)

• ARM support for LLVM/clang Getting LLVM work on ARM #10150

[zephyrbot]

by Mark Linkmeyer:

Moved to 1.10 per review with Chris

[nashif]

depends on Cmake integration.

Some platforms will be able to build, but not link, so we need gcc as well.

[Skjerve]

Is this still on track for 1.12?

[galak]

how far did you get with llvm, any instructions on how to replicate what you have so far?

[marc-hb]

Mentioning clang PR #14077 just for the record, I understand it's only for host toolchain and x86

[raveslave]

Anyone running their projects as native_posix + LLVM in Xcode (macOS) ?

[ochipara]

I am trying to use llvm/clang to build the helloworld sample. I have managed to run through the cmake configuration, but I am running into some compilation issues. Specifically, the following clang gets stuck trying to compile the following asm instruction:
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/kernel/fatal.c:7:
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/include/kernel.h:17:
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/include/kernel_includes.h:34:
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/include/arch/cpu.h:17:
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/include/arch/arm/arch.h:33:
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/include/arch/arm/asm_inline.h:18:
/Users/ochipara/Working/embedded/zephyrproject/zephyr/include/arch/arm/asm_inline_gcc.h:86:3: error: invalid operand for instruction
"mov %1, %2;"
^
:1:22: note: instantiated into assembly here
mov r1, #32;mrs r0, BASEPRI;msr BASEPRI, r1;isb;
^
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/kernel/fatal.c:7:
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/include/kernel.h:17:
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/include/kernel_includes.h:34:
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/include/arch/cpu.h:17:
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/include/arch/arm/arch.h:33:
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/include/arch/arm/asm_inline.h:18:
/Users/ochipara/Working/embedded/zephyrproject/zephyr/include/arch/arm/asm_inline_gcc.h:86:3: error: invalid operand for instruction
"mov %1, %2;"
^
:1:34: note: instantiated into assembly here
mov r1, #32;mrs r0, BASEPRI;msr BASEPRI, r1;isb;
^
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/kernel/fatal.c:7:
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/include/kernel.h:17:
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/include/kernel_includes.h:34:
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/include/arch/cpu.h:17:
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/include/arch/arm/arch.h:33:
In file included from /Users/ochipara/Working/embedded/zephyrproject/zephyr/include/arch/arm/asm_inline.h:18:
/Users/ochipara/Working/embedded/zephyrproject/zephyr/include/arch/arm/asm_inline_gcc.h:86:3: error: instruction requires: data-barriers
"mov %1, %2;"
^
:1:46: note: instantiated into assembly here
mov r1, #32;mrs r0, BASEPRI;msr BASEPRI, r1;isb;

Any suggestions on how this may be fixed? Thanks!

[jettr]

We are very interested in LLVM support for ARM (and RISC-V). Is this something that is realistic for 2.5?

[galak]

We are very interested in LLVM support for ARM (and RISC-V). Is this something that is realistic for 2.5?

@jettr - curious what config of LLVM you guys are interested in? Meaning I assume this means clang, but which linker and assembler are you guys interested in utilizing.

[jettr]

Yes, we would be using Clang and LLD ideally with compiler-rt

[msink]

Ideally support for generic clang/llvm toolchain for ARM - it can open doors for programming on modern llvm based languages, like Rust or Kotlin.

[markand]

I come a little bit late into the party but I'm interested in this as well since clang is de-facto a cross compiler which does not require to rebuild GCC in many flavors (all that triplets that you know of). I'm pretty confident with LLVM builds and its toolchains but not in the embedded areas. For curiosity I've built some apps for zephyr using verbose ninja rules and was surprised to see how many linker options are required so I may help in the LLVM process but may not in the ARM and other platforms specific options.

[zzzh]

there's already a LLVM Embedded Toolchain for Arm, please get it supported!!!

[zzzh]

Sorry, just realized that it's a bare-metal toolchain.

[hakehuang]

@nashif any planning to support this?