When building only radeonsi and radv, Mesa builds fails like this:

[1135/1135] Linking target src/gallium/targets/dri/libgallium_dri.so.
FAILED: src/gallium/targets/dri/libgallium_dri.so 
g++-9  -o src/gallium/targets/dri/libgallium_dri.so <...>
/usr/bin/ld: src/gallium/auxiliary/libgallium.a(gallivm_lp_bld_init.c.o): in function `init_gallivm_state':
lp_bld_init.c:(.text+0x2ad): undefined reference to `LLVMAddCoroEarlyPass'
/usr/bin/ld: lp_bld_init.c:(.text+0x2b6): undefined reference to `LLVMAddCoroSplitPass'
/usr/bin/ld: lp_bld_init.c:(.text+0x2bf): undefined reference to `LLVMAddCoroElidePass'
/usr/bin/ld: lp_bld_init.c:(.text+0x31d): undefined reference to `LLVMAddCoroCleanupPass'
collect2: error: ld returned 1 exit status
ninja: build stopped: subcommand failed.
build failed!

To fix, it, llvm coroutines module can be enabled for example like this:

diff --git a/meson.build b/meson.build
index 29d7981d13d..9ca40e3e896 100644
--- a/meson.build
+++ b/meson.build
@@ -1244,7 +1244,7 @@ endif
 llvm_modules = ['bitwriter', 'engine', 'mcdisassembler', 'mcjit']
 llvm_optional_modules = []
 if with_amd_vk or with_gallium_radeonsi or with_gallium_r600
-  llvm_modules += ['amdgpu', 'native', 'bitreader', 'ipo']
+  llvm_modules += ['amdgpu', 'native', 'bitreader', 'ipo', 'coroutines']
   if with_gallium_r600
     llvm_modules += 'asmparser'
   endif