Re: [LLVMdev] Cc llvmdev: Re: llvm bpf debug info. Re: [RFC PATCH v4 3/3] bpf: Introduce function for outputing data to perf event

[Wangnan (F)]

On 2015/8/5 15:11, Alexei Starovoitov wrote:
> On 8/4/15 11:51 PM, Wangnan (F) wrote:
> > void bpf_store_half(void *skb, int off, int val)
> > asm("llvm.bpf.store.half");
> > int func()
> > {
> >          bpf_store_half(0, 0, 0);
> >          return 0;
> > }
> >
> > Compiled with:
> >
> > $ clang -g -target bpf -O2 -S -c test.c
> >
> > And get this:
> >
> >          .text
> >          .globl  func
> >          .align  8
> > func:                                   # @func
> > # BB#0:                                 # %entry
> >          mov     r1, 0
> >          mov     r2, 0
> >          mov     r3, 0
> >          call    llvm.bpf.store.half
>
> it didn't work because number and types of args were incompatible.
> Every samples/bpf/sockex[0-9]_kern.c is using llvm.bpf.load.* intrinsics.

Make it work. Thank you.

It doesn't work for me at first since in my llvm there's only 
llvm.bpf.load.*.

I think llvm.bpf.store.* belone to some patches you haven't posted yet?

> the typeid changing ids with order is surprising.
> I think the assertion in ExtractTypeInfo() is not hard.
> Just there were no such use cases. May be we can do something
> similar to what LowerIntrinsicCall() does and lower it differently
> in the backend.
But in backend can we still get type information? I thought type is
meaningful in frontend only, and backend behaviors is unable to affect
DWARF generation, right?

Thank you.

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