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Clang/LLVM

http://forum.chibios.org/viewtopic.php?f=3&t=1920

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Re: Clang/LLVM

Posted: Tue Jul 10, 2018 12:46 pm
by Giovanni
Any fix is on the repository, check it out and you have the latest state.

Use this makefile template:

Code: Select all

##############################################################################
# Build global options
# NOTE: Can be overridden externally.
#

# Compiler options here.
ifeq ($(USE_OPT),)
  USE_OPT = -O2 -ggdb -fomit-frame-pointer -falign-functions=16
endif

# C specific options here (added to USE_OPT).
ifeq ($(USE_COPT),)
  USE_COPT =
endif

# C++ specific options here (added to USE_OPT).
ifeq ($(USE_CPPOPT),)
  USE_CPPOPT = -fno-rtti
endif

# Enable this if you want the linker to remove unused code and data.
ifeq ($(USE_LINK_GC),)
  USE_LINK_GC = yes
endif

# Linker extra options here.
ifeq ($(USE_LDOPT),)
  USE_LDOPT =
endif

# Enable this if you want link time optimizations (LTO).
ifeq ($(USE_LTO),)
  USE_LTO = yes
endif

# Enable this if you want to see the full log while compiling.
ifeq ($(USE_VERBOSE_COMPILE),)
  USE_VERBOSE_COMPILE = no
endif

# If enabled, this option makes the build process faster by not compiling
# modules not used in the current configuration.
ifeq ($(USE_SMART_BUILD),)
  USE_SMART_BUILD = yes
endif

#
# Build global options
##############################################################################

##############################################################################
# Architecture or project specific options
#

# Stack size to be allocated to the Cortex-M process stack. This stack is
# the stack used by the main() thread.
ifeq ($(USE_PROCESS_STACKSIZE),)
  USE_PROCESS_STACKSIZE = 0x400
endif

# Stack size to the allocated to the Cortex-M main/exceptions stack. This
# stack is used for processing interrupts and exceptions.
ifeq ($(USE_EXCEPTIONS_STACKSIZE),)
  USE_EXCEPTIONS_STACKSIZE = 0x400
endif

# Enables the use of FPU (no, softfp, hard).
ifeq ($(USE_FPU),)
  USE_FPU = no
endif

# FPU-related options.
ifeq ($(USE_FPU_OPT),)
  USE_FPU_OPT = -mfloat-abi=$(USE_FPU) -mfpu=fpv4-sp-d16
endif

#
# Architecture or project specific options
##############################################################################

##############################################################################
# Project, target, sources and paths
#

# Define project name here
PROJECT = ch

# Target settings.
MCU  = cortex-m4 --target=arm-none-eabi -march=armv7em

# Imported source files and paths.
CHIBIOS = ../../..
CONFDIR  := ./cfg
BUILDDIR := ./build
DEPDIR   := ./.dep

# Licensing files.
include $(CHIBIOS)/os/license/license.mk
# Startup files.
include $(CHIBIOS)/os/common/startup/ARMCMx/compilers/LLVM/mk/startup_stm32f4xx.mk
# HAL-OSAL files (optional).
include $(CHIBIOS)/os/hal/hal.mk
include $(CHIBIOS)/os/hal/ports/STM32/STM32F4xx/platform.mk
include $(CHIBIOS)/os/hal/boards/ST_NUCLEO64_F401RE/board.mk
include $(CHIBIOS)/os/hal/osal/rt/osal.mk
# RTOS files (optional).
include $(CHIBIOS)/os/rt/rt.mk
include $(CHIBIOS)/os/common/ports/ARMCMx/compilers/GCC/mk/port_v7m.mk
# Auto-build files in ./source recursively.
include $(CHIBIOS)/tools/mk/autobuild.mk
# Other files (optional).
include $(CHIBIOS)/test/lib/test.mk
include $(CHIBIOS)/test/rt/rt_test.mk
include $(CHIBIOS)/test/oslib/oslib_test.mk

# Define linker script file here.
LDSCRIPT= $(STARTUPLD)/STM32F401xE.ld

# C sources that can be compiled in ARM or THUMB mode depending on the global
# setting.
CSRC = $(ALLCSRC) \
       $(TESTSRC) \
       main.c

# C++ sources that can be compiled in ARM or THUMB mode depending on the global
# setting.
CPPSRC = $(ALLCPPSRC)

# List ASM source files here.
ASMSRC = $(ALLASMSRC)

# List ASM with preprocessor source files here.
ASMXSRC = $(ALLXASMSRC)

# Inclusion directories.
INCDIR = $(CONFDIR) $(ALLINC) $(TESTINC)

# Define C warning options here.
CWARN = -Wall -Wextra -Wundef -Wstrict-prototypes

# Define C++ warning options here.
CPPWARN = -Wall -Wextra -Wundef

#
# Project, target, sources and paths
##############################################################################

##############################################################################
# Start of user section
#

# List all user C define here, like -D_DEBUG=1
UDEFS =

# Define ASM defines here
UADEFS =

# List all user directories here
UINCDIR =

# List the user directory to look for the libraries here
ULIBDIR =

# List all user libraries here
ULIBS =

#
# End of user section
##############################################################################

##############################################################################
# Common rules
#

RULESPATH = $(CHIBIOS)/os/common/startup/ARMCMx/compilers/LLVM/mk
include $(RULESPATH)/clang.mk
include $(RULESPATH)/rules.mk

#
# Common rules
##############################################################################

##############################################################################
# Custom rules
#

#
# Custom rules
##############################################################################


Giovanni

Re: Clang/LLVM

Posted: Tue Jul 10, 2018 1:06 pm
by Giovanni
I just committed some missing files and last updates, still not complete FYI.

Giovanni

Re: Clang/LLVM

Posted: Mon Jul 16, 2018 8:13 am
by kiran
I am using the latest trunk source , but currently i am stuck with below linking error :
build/bin/ld.lld: error: unable to find library -lclang_rt.builtins-arm.a
I did downloaded the lib and provided the path in makefile but still its not picked up (ldd might be looking at a specific path for this).

Any help of this from your experience on building with clang.

Regards,
Kiran

Re: Clang/LLVM

Posted: Fri Apr 16, 2021 3:53 am
by russian
Giovanni wrote:The problem I can see is that there is no real support except for Linux

but Windows Subsystem for Linux is amazing and it gives all us Windows 10 users our own Linux :)

Poke clang support?

Re: Clang/LLVM

Posted: Fri Apr 16, 2021 4:37 am
by FXCoder
WSL2 is OK for Linux compute stuff you want to do.
And even Docker containers work with desktop Docker for Windows.
But still no USB support....

Re: Clang/LLVM

Posted: Fri Apr 16, 2021 5:23 am
by russian
FXCoder wrote:But still no USB support....

I am 100% sure that USB support is not needed in order to compile ChibiOS with clang under WSL2

Re: Clang/LLVM

Posted: Fri Apr 16, 2021 5:41 am
by Giovanni
Clang should already be supported, I tried it a while ago, did something break in the meanwhile? (I will check)

See /os/common/startup/ARMCMx/compilers/LLVM/mk

Note that I tried the LLVM-based Hightec compiler, which is proprietary. Results were below GCC, especially for code size, so I have not given it much attention anymore.

I found this guide:

https://interrupt.memfault.com/blog/arm ... -baremetal

It shows how use the precompiled libraries in GCC with LLVM for targeting bare-metal, maybe you could give it a try.

Giovanni

Re: Clang/LLVM

Posted: Fri Apr 16, 2021 8:12 am
by alex31
Hello,

I will continue to use GCC for code generation, but CLANG offers very nice clang-tidy static analyser that is lacking in GCC.

A.

Re: Clang/LLVM

Posted: Fri Apr 16, 2021 8:51 am
by Giovanni
alex31 wrote:Hello,

I will continue to use GCC for code generation, but CLANG offers very nice clang-tidy static analyser that is lacking in GCC.

A.


It would be nice to try it, currently ChibiOS is checked using PClint, it is not free however.

Giovanni

Re: Clang/LLVM

Posted: Fri May 07, 2021 3:26 pm
by faisal
Giovanni wrote:Clang should already be supported, I tried it a while ago, did something break in the meanwhile? (I will check)

See /os/common/startup/ARMCMx/compilers/LLVM/mk

Note that I tried the LLVM-based Hightec compiler, which is proprietary. Results were below GCC, especially for code size, so I have not given it much attention anymore.

I found this guide:

https://interrupt.memfault.com/blog/arm ... -baremetal

It shows how use the precompiled libraries in GCC with LLVM for targeting bare-metal, maybe you could give it a try.

Giovanni


I downloaded the latest clang+llvm (12.0.0) and gave it a whirl. A few problems.

* Looking at clang.mk, TRGT=aarch32 . This doesn't make sense, there are no programs in <clang-llvm-path>/bin that start with 'aarch32' . TRGT should be 'llvm' .
* Per the memfault interrupt blog post as well as others, it is recommended to use libc, libm, and builtins from the GNU ARM GCC distribution. I don't see anything in llvm/mk/rules.mk to suggest that it is doing that.
* LD is defined as clang. Not sure if the llvm linker is ready for prime-time, it didnt work on my end. I compiled with clang, and linked with arm-none-eabi-gcc and that worked.

Basically - how did you get it to work without addressing the above?
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