[Mlir-commits] [mlir] [mlir][RegionBranchOpInterface] explicitly check for existance of block terminator (PR #76831)

[Maksim Levental]

https://github.com/makslevental created https://github.com/llvm/llvm-project/pull/76831

`RegionBranchTerminatorOpInterface` doesn't explicitly assume existence of [block terminators](https://github.com/llvm/llvm-project/blob/759cefb70fd13284c782971aa252b453051945bf/mlir/lib/Interfaces/ControlFlowInterfaces.cpp#L187):

```cpp
    // If there is no return-like terminator, the op itself should verify
    // type consistency.
    if (regionReturnOps.empty())
      continue;
```

but it does implicitly because `block.getTerminator()`

```cpp
    SmallVector<RegionBranchTerminatorOpInterface> regionReturnOps;
    for (Block &block : region)
      if (auto terminator = dyn_cast<RegionBranchTerminatorOpInterface>(
              block.getTerminator()))
        regionReturnOps.push_back(terminator);
``` 

does `assert(mightHaveTerminator());`. So just make that explicit.



>From 759cefb70fd13284c782971aa252b453051945bf Mon Sep 17 00:00:00 2001
From: max <maksim.levental at gmail.com>
Date: Wed, 3 Jan 2024 10:26:48 -0600
Subject: [PATCH] [mlir][RegionBranchOpInterface] explicitly check for
 existance of block terminator

---
 mlir/lib/Interfaces/ControlFlowInterfaces.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/mlir/lib/Interfaces/ControlFlowInterfaces.cpp b/mlir/lib/Interfaces/ControlFlowInterfaces.cpp
index 4ed024ddae247b..0585e2ee5e0218 100644
--- a/mlir/lib/Interfaces/ControlFlowInterfaces.cpp
+++ b/mlir/lib/Interfaces/ControlFlowInterfaces.cpp
@@ -177,7 +177,10 @@ LogicalResult detail::verifyTypesAlongControlFlowEdges(Operation *op) {
 
     SmallVector<RegionBranchTerminatorOpInterface> regionReturnOps;
     for (Block &block : region)
-      if (auto terminator = dyn_cast<RegionBranchTerminatorOpInterface>(
+      if (block.mightHaveTerminator() &&
+              dyn_cast<RegionBranchTerminatorOpInterface>(
+                  block.getTerminator());
+          auto terminator = dyn_cast<RegionBranchTerminatorOpInterface>(
               block.getTerminator()))
         regionReturnOps.push_back(terminator);