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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