================
@@ -48,6 +48,13 @@ def BPF_END : BPFArithOp<0xd>;
def BPF_XCHG : BPFArithOp<0xe>;
def BPF_CMPXCHG : BPFArithOp<0xf>;
+class BPFAtomicLoadStoreOp<bits<4> val> {
+ bits<4> Value = val;
+}
+
+def BPF_LOAD_ACQ : BPFAtomicLoadStoreOp<0x1>;
+def BPF_STORE_REL : BPFAtomicLoadStoreOp<0xb>;
----------------
peilin-ye wrote:
@yonghong-song, my thinking was:
Right now for `BPF_ATOMIC` insns, we use a subset of `BPFArithOp<>` in `imm`:
```
def BPF_ADD : BPFArithOp<0x0>;
def BPF_OR : BPFArithOp<0x4>;
def BPF_AND : BPFArithOp<0x5>;
def BPF_XOR : BPFArithOp<0xa>;
def BPF_XCHG : BPFArithOp<0xe>;
def BPF_CMPXCHG : BPFArithOp<0xf>;
```
Will we ever want to support other `BPFArithOp<>` ops in `BPF_ATOMIC` ? Like,
`0x1` is `BPF_SUB`, but it looks like currently atomic SUB is implemented using
NEG + ADD:
```
// atomic_load_sub can be represented as a neg followed
// by an atomic_load_add.
```
So I thought, "OK, if we don't need to reserve `0x1` for `BPF_SUB`, then I can
use it". Similarly, `0xb` is `BPF_MOV` (moving value between registers), and I
think it's safe to say we'll never need it for `BPF_ATOMIC`.
But `0x2` is `BPF_MUL`; will we ever support atomic multiplication? :-)
- - -
Am I overthinking this? Should I simply use `0x1` and `0x2` ?
https://github.com/llvm/llvm-project/pull/108636
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