1 files changed, 68 insertions, 0 deletions
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyNullifyDebugValueLists.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyNullifyDebugValueLists.cpp
new file mode 100644
index 000000000000..62fa089a94d4
--- /dev/null
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyNullifyDebugValueLists.cpp
@@ -0,0 +1,68 @@
+//=== WebAssemblyNullifyDebugValueLists.cpp - Nullify DBG_VALUE_LISTs   ---===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Nullify DBG_VALUE_LISTs instructions as a temporary measure before we
+/// implement DBG_VALUE_LIST handling in WebAssemblyDebugValueManager.
+/// See https://bugs.llvm.org/show_bug.cgi?id=50361.
+/// TODO Correctly handle DBG_VALUE_LISTs
+///
+//===----------------------------------------------------------------------===//
+
+#include "WebAssembly.h"
+#include "WebAssemblySubtarget.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "wasm-nullify-dbg-value-lists"
+
+namespace {
+class WebAssemblyNullifyDebugValueLists final : public MachineFunctionPass {
+  StringRef getPassName() const override {
+    return "WebAssembly Nullify DBG_VALUE_LISTs";
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+
+public:
+  static char ID; // Pass identification, replacement for typeid
+  WebAssemblyNullifyDebugValueLists() : MachineFunctionPass(ID) {}
+};
+} // end anonymous namespace
+
+char WebAssemblyNullifyDebugValueLists::ID = 0;
+INITIALIZE_PASS(WebAssemblyNullifyDebugValueLists, DEBUG_TYPE,
+                "WebAssembly Nullify DBG_VALUE_LISTs", false, false)
+
+FunctionPass *llvm::createWebAssemblyNullifyDebugValueLists() {
+  return new WebAssemblyNullifyDebugValueLists();
+}
+
+bool WebAssemblyNullifyDebugValueLists::runOnMachineFunction(
+    MachineFunction &MF) {
+  LLVM_DEBUG(dbgs() << "********** Nullify DBG_VALUE_LISTs **********\n"
+                       "********** Function: "
+                    << MF.getName() << '\n');
+  const auto &TII = *MF.getSubtarget<WebAssemblySubtarget>().getInstrInfo();
+  SmallVector<MachineInstr *, 2> DbgValueLists;
+  for (auto &MBB : MF)
+    for (auto &MI : MBB)
+      if (MI.getOpcode() == TargetOpcode::DBG_VALUE_LIST)
+        DbgValueLists.push_back(&MI);
+
+  // Our backend, including WebAssemblyDebugValueManager, currently cannot
+  // handle DBG_VALUE_LISTs correctly. So this converts DBG_VALUE_LISTs to
+  // "DBG_VALUE $noreg", which will appear as "optimized out".
+  for (auto *DVL : DbgValueLists) {
+    BuildMI(*DVL->getParent(), DVL, DVL->getDebugLoc(),
+            TII.get(TargetOpcode::DBG_VALUE), false, Register(),
+            DVL->getOperand(0).getMetadata(), DVL->getOperand(1).getMetadata());
+    DVL->eraseFromParent();
+  }
+
+  return !DbgValueLists.empty();
+}