Fix RemoveDeadValues: Bail out early when there are no terminators

[hiraditya]

Fixes: #131765

[llvmbot]

@llvm/pr-subscribers-mlir-core

@llvm/pr-subscribers-mlir

Author: AdityaK (hiraditya)

Changes

Fixes: #131765

---

Full diff: https://github.com/llvm/llvm-project/pull/133316.diff

2 Files Affected:

• (modified) mlir/lib/Transforms/RemoveDeadValues.cpp (+2)
• (modified) mlir/test/Transforms/remove-dead-values.mlir (+15)

diff --git a/mlir/lib/Transforms/RemoveDeadValues.cpp b/mlir/lib/Transforms/RemoveDeadValues.cpp
index c20c54551cdf8..92c05d87a002d 100644
--- a/mlir/lib/Transforms/RemoveDeadValues.cpp
+++ b/mlir/lib/Transforms/RemoveDeadValues.cpp
@@ -305,6 +305,8 @@ static void processFuncOp(FunctionOpInterface funcOp, Operation *module,
   // since it forwards only to non-live value(s) (%1#1).
   Operation *lastReturnOp = funcOp.back().getTerminator();
   size_t numReturns = lastReturnOp->getNumOperands();
+  if (numReturns == 0)
+    return;
   BitVector nonLiveRets(numReturns, true);
   for (SymbolTable::SymbolUse use : uses) {
     Operation *callOp = use.getUser();
diff --git a/mlir/test/Transforms/remove-dead-values.mlir b/mlir/test/Transforms/remove-dead-values.mlir
index e549926b90456..21d53b0742e07 100644
--- a/mlir/test/Transforms/remove-dead-values.mlir
+++ b/mlir/test/Transforms/remove-dead-values.mlir
@@ -446,6 +446,21 @@ func.func @kernel(%arg0: memref<18xf32>) {
 
 // -----
 
+
+// CHECK-LABEL: llvm_unreachable
+// CHECK-LABEL: @fn_with_llvm_unreachable
+// CHECK-LABEL: @main
+// CHECK: llvm.return
+module @llvm_unreachable {
+  func.func private @fn_with_llvm_unreachable(%arg0: tensor<4x4xf32>) -> tensor<4x4xi1> {
+    llvm.unreachable
+  }
+  func.func private @main(%arg0: tensor<4x4xf32>) {
+    %0 = call @fn_with_llvm_unreachable(%arg0) : (tensor<4x4xf32>) -> tensor<4x4xi1>
+    llvm.return
+  }
+}
+
 // CHECK: func.func private @no_block_func_declaration()
 func.func private @no_block_func_declaration() -> ()
 

[srishti-pm]

LGTM