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...
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