eddyz87 wrote:
@peilin-ye,
> I couldn't find a way to generate a better error message for
> `__ATOMIC_SEQ_CST`, however; it seems that CodeGen simply calls
> `CannotYetSelect()` if nothing in `MatcherTable` matches. Any suggestions?
There is probably some tablegen incantation to invoke custom cpp for some
matched pattern but I haven't found it. Also I have not found any target info
hooks for clang to report unsupported orderings.
One option is to extend existing mechanics:
```diff
diff --git a/llvm/lib/Target/BPF/BPFISelLowering.cpp
b/llvm/lib/Target/BPF/BPFISelLowering.cpp
index ff23d3b055d0..9e54c7f3de65 100644
--- a/llvm/lib/Target/BPF/BPFISelLowering.cpp
+++ b/llvm/lib/Target/BPF/BPFISelLowering.cpp
@@ -91,6 +91,7 @@ BPFTargetLowering::BPFTargetLowering(const TargetMachine &TM,
setOperationAction(ISD::ATOMIC_LOAD_XOR, VT, Custom);
setOperationAction(ISD::ATOMIC_SWAP, VT, Custom);
setOperationAction(ISD::ATOMIC_CMP_SWAP_WITH_SUCCESS, VT, Custom);
+ setOperationAction(ISD::ATOMIC_LOAD, VT, Custom);
}
for (auto VT : { MVT::i32, MVT::i64 }) {
@@ -291,6 +292,14 @@ void BPFTargetLowering::ReplaceNodeResults(
else
Msg = "unsupported atomic operation, please use 64 bit version";
break;
+ case ISD::ATOMIC_LOAD: {
+ auto *AtomicLoad = cast<AtomicSDNode>(N);
+ if (AtomicLoad->getMergedOrdering() != AtomicOrdering::AcquireRelease &&
+ AtomicLoad->getMergedOrdering() !=
AtomicOrdering::SequentiallyConsistent)
+ return;
+ Msg = "a useful message about unsupported ordering here";
+ break;
+ }
}
SDLoc DL(N);
{llvm} 02:29:45 llvm-project$ git diff
diff --git a/llvm/lib/Target/BPF/BPFISelLowering.cpp
b/llvm/lib/Target/BPF/BPFISelLowering.cpp
index ff23d3b055d0..9e54c7f3de65 100644
--- a/llvm/lib/Target/BPF/BPFISelLowering.cpp
+++ b/llvm/lib/Target/BPF/BPFISelLowering.cpp
@@ -91,6 +91,7 @@ BPFTargetLowering::BPFTargetLowering(const TargetMachine &TM,
setOperationAction(ISD::ATOMIC_LOAD_XOR, VT, Custom);
setOperationAction(ISD::ATOMIC_SWAP, VT, Custom);
setOperationAction(ISD::ATOMIC_CMP_SWAP_WITH_SUCCESS, VT, Custom);
+ setOperationAction(ISD::ATOMIC_LOAD, VT, Custom);
}
for (auto VT : { MVT::i32, MVT::i64 }) {
@@ -291,6 +292,14 @@ void BPFTargetLowering::ReplaceNodeResults(
else
Msg = "unsupported atomic operation, please use 64 bit version";
break;
+ case ISD::ATOMIC_LOAD: {
+ auto *AtomicLoad = cast<AtomicSDNode>(N);
+ if (AtomicLoad->getMergedOrdering() != AtomicOrdering::AcquireRelease &&
+ AtomicLoad->getMergedOrdering() !=
AtomicOrdering::SequentiallyConsistent)
+ return;
+ Msg = "a useful message about unsupported ordering here";
+ break;
+ }
}
SDLoc DL(N);
```
When compiled with `-g` this would report location and a message before
complaining about selection error. But there should be a way to tweak existing
`fail` function to stop after errors are reported.
https://github.com/llvm/llvm-project/pull/108636
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