1 files changed, 113 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/GlobalISel/LostDebugLocObserver.cpp b/llvm/lib/CodeGen/GlobalISel/LostDebugLocObserver.cpp
new file mode 100644
index 000000000000..6d606e5550f1
--- /dev/null
+++ b/llvm/lib/CodeGen/GlobalISel/LostDebugLocObserver.cpp
@@ -0,0 +1,113 @@
+//===----- llvm/CodeGen/GlobalISel/LostDebugLocObserver.cpp -----*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+/// Tracks DebugLocs between checkpoints and verifies that they are transferred.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/GlobalISel/LostDebugLocObserver.h"
+
+using namespace llvm;
+
+#define LOC_DEBUG(X) DEBUG_WITH_TYPE(DebugType.str().c_str(), X)
+
+void LostDebugLocObserver::analyzeDebugLocations() {
+  if (LostDebugLocs.empty()) {
+    LOC_DEBUG(dbgs() << ".. No debug info was present\n");
+    return;
+  }
+  if (PotentialMIsForDebugLocs.empty()) {
+    LOC_DEBUG(
+        dbgs() << ".. No instructions to carry debug info (dead code?)\n");
+    return;
+  }
+
+  LOC_DEBUG(dbgs() << ".. Searching " << PotentialMIsForDebugLocs.size()
+                   << " instrs for " << LostDebugLocs.size() << " locations\n");
+  SmallPtrSet<MachineInstr *, 4> FoundIn;
+  for (MachineInstr *MI : PotentialMIsForDebugLocs) {
+    if (!MI->getDebugLoc())
+      continue;
+    // Check this first in case there's a matching line-0 location on both input
+    // and output.
+    if (MI->getDebugLoc().getLine() == 0) {
+      LOC_DEBUG(
+          dbgs() << ".. Assuming line-0 location covers remainder (if any)\n");
+      return;
+    }
+    if (LostDebugLocs.erase(MI->getDebugLoc())) {
+      LOC_DEBUG(dbgs() << ".. .. found " << MI->getDebugLoc() << " in " << *MI);
+      FoundIn.insert(MI);
+      continue;
+    }
+  }
+  if (LostDebugLocs.empty())
+    return;
+
+  NumLostDebugLocs += LostDebugLocs.size();
+  LOC_DEBUG({
+    dbgs() << ".. Lost locations:\n";
+    for (const DebugLoc &Loc : LostDebugLocs) {
+      dbgs() << ".. .. ";
+      Loc.print(dbgs());
+      dbgs() << "\n";
+    }
+    dbgs() << ".. MIs with matched locations:\n";
+    for (MachineInstr *MI : FoundIn)
+      if (PotentialMIsForDebugLocs.erase(MI))
+        dbgs() << ".. .. " << *MI;
+    dbgs() << ".. Remaining MIs with unmatched/no locations:\n";
+    for (const MachineInstr *MI : PotentialMIsForDebugLocs)
+      dbgs() << ".. .. " << *MI;
+  });
+}
+
+void LostDebugLocObserver::checkpoint(bool CheckDebugLocs) {
+  if (CheckDebugLocs)
+    analyzeDebugLocations();
+  PotentialMIsForDebugLocs.clear();
+  LostDebugLocs.clear();
+}
+
+void LostDebugLocObserver::createdInstr(MachineInstr &MI) {
+  PotentialMIsForDebugLocs.insert(&MI);
+}
+
+static bool irTranslatorNeverAddsLocations(unsigned Opcode) {
+  switch (Opcode) {
+  default:
+    return false;
+  case TargetOpcode::G_CONSTANT:
+  case TargetOpcode::G_FCONSTANT:
+  case TargetOpcode::G_IMPLICIT_DEF:
+  case TargetOpcode::G_GLOBAL_VALUE:
+    return true;
+  }
+}
+
+void LostDebugLocObserver::erasingInstr(MachineInstr &MI) {
+  if (irTranslatorNeverAddsLocations(MI.getOpcode()))
+    return;
+
+  PotentialMIsForDebugLocs.erase(&MI);
+  if (MI.getDebugLoc())
+    LostDebugLocs.insert(MI.getDebugLoc());
+}
+
+void LostDebugLocObserver::changingInstr(MachineInstr &MI) {
+  if (irTranslatorNeverAddsLocations(MI.getOpcode()))
+    return;
+
+  PotentialMIsForDebugLocs.erase(&MI);
+  if (MI.getDebugLoc())
+    LostDebugLocs.insert(MI.getDebugLoc());
+}
+
+void LostDebugLocObserver::changedInstr(MachineInstr &MI) {
+  PotentialMIsForDebugLocs.insert(&MI);
+}