FYI, I'm observing more instruction reordering with >=3.9 as compared to 3.8 for the same code. You might need the following fix:
http://git.kernel.org/cgit/linux/kernel/git/davem/net-next.git/commit/?id=57a09bf0a416700676e77102c28f9cfcb48267e0 On Sun, Oct 23, 2016 at 4:35 PM, William Tu via iovisor-dev <[email protected]> wrote: > Thanks! I upgrade LLVM to 4.0.0 and this error no longer shows up. > William > > On Sat, Oct 22, 2016 at 8:33 AM, Alexei Starovoitov > <[email protected]> wrote: >> On Fri, Oct 21, 2016 at 11:38 PM, William Tu via iovisor-dev >> <[email protected]> wrote: >>> Hi, >>> I'm running into this LLVM ERROR at compile time. Does anyone seem >>> this before or can give me some suggestions? thanks! >>> >>> ------- >>> LLVM ERROR: Cannot select: 0x3bafa28: ch = brind 0x3bc98f0:1, >>> 0x3bc98f0 [ORD=1] [ID=9] >>> 0x3bc98f0: i64,ch = load 0x3bb0db0:1, 0x3baf588, >>> 0x3bc8c58<LD8[JumpTable]> [ORD=1] [ID=8] >>> 0x3baf588: i64 = add 0x3bade48, 0x3bb06c0 [ORD=1] [ID=7] >>> 0x3bade48: i64 = shl 0x3bb0db0, 0x3bb0470 [ORD=1] [ID=6] >>> 0x3bb0db0: i64,ch = CopyFromReg 0x3b78a00, 0x3bad2b8 [ORD=1] [ID=5] >>> 0x3bad2b8: i64 = Register %vreg1 [ID=1] >>> 0x3bb0470: i64 = Constant<3> [ID=4] >>> 0x3bb06c0: i64 = JumpTable<0> [ID=2] >>> 0x3bc8c58: i64 = Constant<0> [ID=3] >>> In function: main_proto >>> samples/bpf/Makefile:128: recipe for target 'samples/bpf/sockex3_kern.o' >>> failed >>> >>> My C code is below: >>> ---------------------------------- >>> SEC("socket/0") >>> static int main_proto(struct __sk_buff *skb) >>> { >>> u32 proto2 = skb->cb[1]; >>> switch (proto2) { >>> case 0: >>> skb->cb[2]= 0; >>> break; >>> case 1: >>> skb->cb[2]= 1; >>> break; >>> case 2: >>> skb->cb[2]= 2; >>> break; >>> case 3: >>> skb->cb[2]= 3; >>> break; >>> default: >>> break; >>> } >>> return 0; >>> } >>> >>> I found that removing "case 3" will prevent the error, but then I >>> could only have 3 cases. >>> [root@vm-dev bpf]# clang --version >>> clang version 3.7.0 (tags/RELEASE_370/final) >>> [root@vm-dev lib]# llc --version >>> LLVM (http://llvm.org/): >>> LLVM version 3.7.0 >> >> 3.7.0 has several known bugs. Please upgrade to 3.7.1 or higher. >> jumptable should have been converted to branches by backend... > _______________________________________________ > iovisor-dev mailing list > [email protected] > https://lists.iovisor.org/mailman/listinfo/iovisor-dev _______________________________________________ iovisor-dev mailing list [email protected] https://lists.iovisor.org/mailman/listinfo/iovisor-dev
