clang

Compiling DragonFly BSD using llvm/clang

This page tracks the progress on an effort to compile DragonFly with llvm/clang instead of gcc.

First, you'll need to build clang as described here (it builds out of the box on DragonFly).

cd /usr/src
env WORLD_CCVER=clang make -DNO_GCC44 buildworld
env WORLD_CCVER=clang make buildkernel KERNCONF=...

Type	llvm/clang revision	Status	Remarks
GENERIC	66925	Doesn't compile	Filed llvm/clang bug ~~#3805~~
GENERIC	67025	Doesn't link (ncr, nsp, tmc)	This commit should fix it
GENERIC	67025	Compiles, doesn't boot	(see Current Log) - Filed llvm/clang bug #3812.
GENERIC	67025	Boots, seems to work ok	network adapters removed from system
GENERIC	67025	Boots, survives stress test (buildworld)

Type	llvm/clang revision	Status	Problem area	Remarks
world	67025	Doesn't compile	all	Filed llvm/clang bug ~~#3853~~
world	69545	Partially compiles	lib/libc	Issue with zero-size arrays (see note below), filed llvm/clang bug #4020 Edit: This commit solves this issue

Bug #	Bug Description	Affects	Status
3805	ccc ignores -x assembler-with-cpp	build of locore.s	Fixed
3812	assembler doesn't properly process clobber,input and output register lists	atomic_intr_cond_try in atomic.h	Closed
3822	failed assertion with -O2	build of GENERIC with -O2	Fixed
3853	__thread keyword not supported	build of all userland base tools	Fixed
4007	clang doesn't know -Werror-foo is the same as -Werror=foo	barrage of warnings during make depend	Fixed
4020	clang doesn't allow zero-sized arrays	build of lib/libc	Closed (won't fix)
4022	incorrect handling of __inline	build of LINT	Closed

The long standing atomic_intr_cond_try issue has been solved in commit caae4d604234d17dff3080f60624a583965c2cf4.

llvm/clang doesn't support zero sized arrays and automatically generates arrays with a size 1 when a zero-size array is specified.

NOTE: This issue has been fixed in this commit.