[RemoveDIs][BC] Reject intrinsic->record upgrades for old-format modules (#87494)

Fixes issue noted at: #86274

When loading bitcode lazily, we may request debug intrinsics be upgraded
to debug records during the module parsing phase; later on we perform
this upgrade when materializing the module functions. If we change the
module's debug info format between parsing and materializing however,
then the requested upgrade is no longer correct and leads to an
assertion. This patch fixes the issue by adding an extra check in the
autoupgrader to see if the upgrade is no longer suitable, and either
exit-out or fall back to the correct intrinsic->intrinsic upgrade if one
is required.

Author: SLTozer

llvm/include/llvm/IR/AutoUpgrade.h

@@ -36,7 +36,8 @@ namespace llvm {
   /// for upgrading, and returns true if it requires upgrading. It may return
   /// null in NewFn if the all calls to the original intrinsic function
   /// should be transformed to non-function-call instructions.
-  bool UpgradeIntrinsicFunction(Function *F, Function *&NewFn);
+  bool UpgradeIntrinsicFunction(Function *F, Function *&NewFn,
+                                bool CanUpgradeDebugIntrinsicsToRecords = true);
 
   /// This is the complement to the above, replacing a specific call to an
   /// intrinsic function with a call to the specified new function.

llvm/lib/IR/AutoUpgrade.cpp

@@ -983,7 +983,8 @@ static Intrinsic::ID shouldUpgradeNVPTXBF16Intrinsic(StringRef Name) {
   return Intrinsic::not_intrinsic;
 }
 
-static bool upgradeIntrinsicFunction1(Function *F, Function *&NewFn) {
+static bool upgradeIntrinsicFunction1(Function *F, Function *&NewFn,
+                                      bool CanUpgradeDebugIntrinsicsToRecords) {
   assert(F && "Illegal to upgrade a non-existent Function.");
 
   StringRef Name = F->getName();
@@ -1057,7 +1058,8 @@ static bool upgradeIntrinsicFunction1(Function *F, Function *&NewFn) {
   case 'd':
     if (Name.consume_front("dbg.")) {
       // Mark debug intrinsics for upgrade to new debug format.
-      if (F->getParent()->IsNewDbgInfoFormat) {
+      if (CanUpgradeDebugIntrinsicsToRecords &&
+          F->getParent()->IsNewDbgInfoFormat) {
         if (Name == "addr" || Name == "value" || Name == "assign" ||
             Name == "declare" || Name == "label") {
           // There's no function to replace these with.
@@ -1413,9 +1415,11 @@ static bool upgradeIntrinsicFunction1(Function *F, Function *&NewFn) {
   return false;
 }
 
-bool llvm::UpgradeIntrinsicFunction(Function *F, Function *&NewFn) {
+bool llvm::UpgradeIntrinsicFunction(Function *F, Function *&NewFn,
+                                    bool CanUpgradeDebugIntrinsicsToRecords) {
   NewFn = nullptr;
-  bool Upgraded = upgradeIntrinsicFunction1(F, NewFn);
+  bool Upgraded =
+      upgradeIntrinsicFunction1(F, NewFn, CanUpgradeDebugIntrinsicsToRecords);
   assert(F != NewFn && "Intrinsic function upgraded to the same function");
 
   // Upgrade intrinsic attributes.  This does not change the function.
@@ -2412,6 +2416,7 @@ void llvm::UpgradeIntrinsicCall(CallBase *CI, Function *NewFn) {
   Builder.SetInsertPoint(CI->getParent(), CI->getIterator());
 
   if (!NewFn) {
+    bool FallthroughToDefaultUpgrade = false;
     // Get the Function's name.
     StringRef Name = F->getName();
 
@@ -4262,16 +4267,30 @@ void llvm::UpgradeIntrinsicCall(CallBase *CI, Function *NewFn) {
       Rep = upgradeARMIntrinsicCall(Name, CI, F, Builder);
     } else if (IsAMDGCN) {
       Rep = upgradeAMDGCNIntrinsicCall(Name, CI, F, Builder);
-    } else if (IsDbg && CI->getModule()->IsNewDbgInfoFormat) {
-      upgradeDbgIntrinsicToDbgRecord(Name, CI);
+    } else if (IsDbg) {
+      // We might have decided we don't want the new format after all between
+      // first requesting the upgrade and now; skip the conversion if that is
+      // the case, and check here to see if the intrinsic needs to be upgraded
+      // normally.
+      if (!CI->getModule()->IsNewDbgInfoFormat) {
+        bool NeedsUpgrade =
+            upgradeIntrinsicFunction1(CI->getCalledFunction(), NewFn, false);
+        if (!NeedsUpgrade)
+          return;
+        FallthroughToDefaultUpgrade = true;
+      } else {
+        upgradeDbgIntrinsicToDbgRecord(Name, CI);
+      }
     } else {
       llvm_unreachable("Unknown function for CallBase upgrade.");
     }
 
-    if (Rep)
-      CI->replaceAllUsesWith(Rep);
-    CI->eraseFromParent();
-    return;
+    if (!FallthroughToDefaultUpgrade) {
+      if (Rep)
+        CI->replaceAllUsesWith(Rep);
+      CI->eraseFromParent();
+      return;
+    }
   }
 
   const auto &DefaultCase = [&]() -> void {