[PATCH] D86495: [CSSPGO] MIR target-independent pseudo instruction for pseudo-probe intrinsic

[Mariusz Ceier via Phabricator via llvm-commits]

mceier added inline comments.


================
Comment at: llvm/include/llvm/CodeGen/SelectionDAGNodes.h:1752-1777
+/// This SDNode is used for PSEUDO_PROBE values, which are the function guid and
+/// the index of the basic block being probed. A pseudo probe serves as a place
+/// holder and will be removed at the end of compilation. It does not have any
+/// operand because we do not want the instruction selection to deal with any.
+class PseudoProbeSDNode : public SDNode {
+  friend class SelectionDAG;
+  uint64_t Guid;
----------------
The size of this class (66 if I computed it correctly) exceeds the size of LargestSDNode (64 bytes) in llvm/include/llvm/CodeGen/SelectionDAGNodes.h causing static_assert to fail in Recycler.h when compiling SelectionDAG.cpp (at least) on 32-bit system:


```
In file included from llvm/include/llvm/CodeGen/MachineFunction.h:35,
                 from llvm/include/llvm/CodeGen/SelectionDAG.h:31,
                 from llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:13:
llvm/include/llvm/Support/Recycler.h: In instantiation of ‘SubClass* llvm::Recycler<T, Size, Align>::Allocate(AllocatorType&) [with SubClass = llvm::PseudoProbeSDNode; AllocatorType = llvm::BumpPtrAllocatorImpl<>; T = llvm::SDNode; unsigned int Size = 64; unsigned int Align = 4]’:
llvm/include/llvm/Support/RecyclingAllocator.h:43:65:   required from ‘SubClass* llvm::RecyclingAllocator<AllocatorType, T, Size, Align>::Allocate() [with SubClass = llvm::PseudoProbeSDNode; AllocatorType = llvm::BumpPtrAllocatorImpl<>; T = llvm::SDNode; unsigned int Size = 64; unsigned int Align = 4]’
llvm/include/llvm/CodeGen/SelectionDAG.h:380:57:   required from ‘SDNodeT* llvm::SelectionDAG::newSDNode(ArgTypes&& ...) [with SDNodeT = llvm::PseudoProbeSDNode; ArgTypes = {const unsigned int&, unsigned int, const llvm::DebugLoc&, const llvm::SDVTList&, long long unsigned int&, long long unsigned int&, unsigned int&}]’
llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp:6906:72:   required from here
llvm/include/llvm/Support/Recycler.h:86:36: error: static assertion failed: Recycler allocation size is less than object size!
   86 |     static_assert(sizeof(SubClass) <= Size,
      |                   ~~~~~~~~~~~~~~~~~^~~~~~~
```

Relevant bug: https://bugs.llvm.org/show_bug.cgi?id=48259

I'm guessing this code in llvm/include/llvm/CodeGen/SelectionDAGNodes.h:

```
using LargestSDNode = AlignedCharArrayUnion<AtomicSDNode, TargetIndexSDNode,
                                            BlockAddressSDNode,
                                            GlobalAddressSDNode>;
```

should be changed to:

```
using LargestSDNode = AlignedCharArrayUnion<AtomicSDNode, TargetIndexSDNode,
                                            BlockAddressSDNode,
                                            GlobalAddressSDNode,
                                            PseudoProbeSDNode>;
```


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D86495/new/

https://reviews.llvm.org/D86495