Fix RemoveDeadValues: Bail out early when there are no terminators (llvm#133316)

Fixes: llvm#131765

Author: hiraditya

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();

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() -> ()