[DebugInfo][RemoveDIs] Remove some debug intrinsic-only codepaths (llvm#143451)

These are opportunistic deletions as more places that make use of the
IsNewDbgInfoFormat flag are removed. It should (TM)(R) all be dead code
now that `IsNewDbgInfoFormat` should be true everywhere.

FastISel: we don't need to do debug-aware instruction counting any more,
because there are no debug instructions,
Autoupgrade: you can no-longer avoid autoupgrading of intrinsics to
records
DIBuilder: Delete the code for creating debug intrinsics (!)
LoopUtils: No need to handle debug instructions, they don't exist

Author: jmorse

llvm/lib/CodeGen/SelectionDAG/FastISel.cpp

@@ -1671,9 +1671,6 @@ void FastISel::fastEmitBranch(MachineBasicBlock *MSucc,
                               const DebugLoc &DbgLoc) {
   const BasicBlock *BB = FuncInfo.MBB->getBasicBlock();
   bool BlockHasMultipleInstrs = &BB->front() != &BB->back();
-  // Handle legacy case of debug intrinsics
-  if (BlockHasMultipleInstrs && !BB->getModule()->IsNewDbgInfoFormat)
-    BlockHasMultipleInstrs = BB->sizeWithoutDebug() > 1;
   if (BlockHasMultipleInstrs && FuncInfo.MBB->isLayoutSuccessor(MSucc)) {
     // For more accurate line information if this is the only non-debug
     // instruction in the block then emit it, otherwise we have the

llvm/lib/IR/AutoUpgrade.cpp

@@ -4490,7 +4490,6 @@ 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();
 
@@ -4518,29 +4517,15 @@ void llvm::UpgradeIntrinsicCall(CallBase *CI, Function *NewFn) {
     } else if (IsAMDGCN) {
       Rep = upgradeAMDGCNIntrinsicCall(Name, CI, F, Builder);
     } 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);
-      }
+      upgradeDbgIntrinsicToDbgRecord(Name, CI);
     } else {
       llvm_unreachable("Unknown function for CallBase upgrade.");
     }
 
-    if (!FallthroughToDefaultUpgrade) {
-      if (Rep)
-        CI->replaceAllUsesWith(Rep);
-      CI->eraseFromParent();
-      return;
-    }
+    if (Rep)
+      CI->replaceAllUsesWith(Rep);
+    CI->eraseFromParent();
+    return;
   }
 
   const auto &DefaultCase = [&]() -> void {

llvm/lib/IR/DIBuilder.cpp

@@ -1047,36 +1047,13 @@ DbgInstPtr DIBuilder::insertDbgAssign(Instruction *LinkedInstr, Value *Val,
       LinkedInstr->getMetadata(LLVMContext::MD_DIAssignID));
   assert(Link && "Linked instruction must have DIAssign metadata attached");
 
-  if (M.IsNewDbgInfoFormat) {
-    DbgVariableRecord *DVR = DbgVariableRecord::createDVRAssign(
-        Val, SrcVar, ValExpr, Link, Addr, AddrExpr, DL);
-    // Insert after LinkedInstr.
-    BasicBlock::iterator NextIt = std::next(LinkedInstr->getIterator());
-    NextIt.setHeadBit(true);
-    insertDbgVariableRecord(DVR, NextIt);
-    return DVR;
-  }
-
-  LLVMContext &Ctx = LinkedInstr->getContext();
-  Module *M = LinkedInstr->getModule();
-  if (!AssignFn)
-    AssignFn = Intrinsic::getOrInsertDeclaration(M, Intrinsic::dbg_assign);
-
-  std::array<Value *, 6> Args = {
-      MetadataAsValue::get(Ctx, ValueAsMetadata::get(Val)),
-      MetadataAsValue::get(Ctx, SrcVar),
-      MetadataAsValue::get(Ctx, ValExpr),
-      MetadataAsValue::get(Ctx, Link),
-      MetadataAsValue::get(Ctx, ValueAsMetadata::get(Addr)),
-      MetadataAsValue::get(Ctx, AddrExpr),
-  };
-
-  IRBuilder<> B(Ctx);
-  B.SetCurrentDebugLocation(DL);
-
-  auto *DVI = cast<DbgAssignIntrinsic>(B.CreateCall(AssignFn, Args));
-  DVI->insertAfter(LinkedInstr->getIterator());
-  return DVI;
+  DbgVariableRecord *DVR = DbgVariableRecord::createDVRAssign(
+      Val, SrcVar, ValExpr, Link, Addr, AddrExpr, DL);
+  // Insert after LinkedInstr.
+  BasicBlock::iterator NextIt = std::next(LinkedInstr->getIterator());
+  NextIt.setHeadBit(true);
+  insertDbgVariableRecord(DVR, NextIt);
+  return DVR;
 }
 
 /// Initialize IRBuilder for inserting dbg.declare and dbg.value intrinsics.
@@ -1101,18 +1078,10 @@ DbgInstPtr DIBuilder::insertDbgValueIntrinsic(llvm::Value *Val,
                                               DIExpression *Expr,
                                               const DILocation *DL,
                                               InsertPosition InsertPt) {
-  if (M.IsNewDbgInfoFormat) {
-    DbgVariableRecord *DVR =
-        DbgVariableRecord::createDbgVariableRecord(Val, VarInfo, Expr, DL);
-    insertDbgVariableRecord(DVR, InsertPt);
-    return DVR;
-  }
-
-  if (!ValueFn)
-    ValueFn = Intrinsic::getOrInsertDeclaration(&M, Intrinsic::dbg_value);
-  auto *DVI = insertDbgIntrinsic(ValueFn, Val, VarInfo, Expr, DL, InsertPt);
-  cast<CallInst>(DVI)->setTailCall();
-  return DVI;
+  DbgVariableRecord *DVR =
+      DbgVariableRecord::createDbgVariableRecord(Val, VarInfo, Expr, DL);
+  insertDbgVariableRecord(DVR, InsertPt);
+  return DVR;
 }
 
 DbgInstPtr DIBuilder::insertDeclare(Value *Storage, DILocalVariable *VarInfo,
@@ -1124,25 +1093,10 @@ DbgInstPtr DIBuilder::insertDeclare(Value *Storage, DILocalVariable *VarInfo,
              VarInfo->getScope()->getSubprogram() &&
          "Expected matching subprograms");
 
-  if (M.IsNewDbgInfoFormat) {
-    DbgVariableRecord *DVR =
-        DbgVariableRecord::createDVRDeclare(Storage, VarInfo, Expr, DL);
-    insertDbgVariableRecord(DVR, InsertPt);
-    return DVR;
-  }
-
-  if (!DeclareFn)
-    DeclareFn = getDeclareIntrin(M);
-
-  trackIfUnresolved(VarInfo);
-  trackIfUnresolved(Expr);
-  Value *Args[] = {getDbgIntrinsicValueImpl(VMContext, Storage),
-                   MetadataAsValue::get(VMContext, VarInfo),
-                   MetadataAsValue::get(VMContext, Expr)};
-
-  IRBuilder<> B(DL->getContext());
-  initIRBuilder(B, DL, InsertPt);
-  return B.CreateCall(DeclareFn, Args);
+  DbgVariableRecord *DVR =
+      DbgVariableRecord::createDVRDeclare(Storage, VarInfo, Expr, DL);
+  insertDbgVariableRecord(DVR, InsertPt);
+  return DVR;
 }
 
 void DIBuilder::insertDbgVariableRecord(DbgVariableRecord *DVR,
@@ -1191,23 +1145,12 @@ DbgInstPtr DIBuilder::insertLabel(DILabel *LabelInfo, const DILocation *DL,
          "Expected matching subprograms");
 
   trackIfUnresolved(LabelInfo);
-  if (M.IsNewDbgInfoFormat) {
-    DbgLabelRecord *DLR = new DbgLabelRecord(LabelInfo, DL);
-    if (InsertPt.isValid()) {
-      auto *BB = InsertPt.getBasicBlock();
-      BB->insertDbgRecordBefore(DLR, InsertPt);
-    }
-    return DLR;
+  DbgLabelRecord *DLR = new DbgLabelRecord(LabelInfo, DL);
+  if (InsertPt.isValid()) {
+    auto *BB = InsertPt.getBasicBlock();
+    BB->insertDbgRecordBefore(DLR, InsertPt);
   }
-
-  if (!LabelFn)
-    LabelFn = Intrinsic::getOrInsertDeclaration(&M, Intrinsic::dbg_label);
-
-  Value *Args[] = {MetadataAsValue::get(VMContext, LabelInfo)};
-
-  IRBuilder<> B(DL->getContext());
-  initIRBuilder(B, DL, InsertPt);
-  return B.CreateCall(LabelFn, Args);
+  return DLR;
 }
 
 void DIBuilder::replaceVTableHolder(DICompositeType *&T, DIType *VTableHolder) {

llvm/lib/IR/DebugInfo.cpp

@@ -2123,22 +2123,11 @@ static void emitDbgAssign(AssignmentInfo Info, Value *Val, Value *Dest,
     Expr = *R;
   }
   DIExpression *AddrExpr = DIExpression::get(StoreLikeInst.getContext(), {});
-  if (StoreLikeInst.getParent()->IsNewDbgInfoFormat) {
-    auto *Assign = DbgVariableRecord::createLinkedDVRAssign(
-        &StoreLikeInst, Val, VarRec.Var, Expr, Dest, AddrExpr, VarRec.DL);
-    (void)Assign;
-    LLVM_DEBUG(if (Assign) errs() << " > INSERT: " << *Assign << "\n");
-    return;
-  }
-  auto Assign = DIB.insertDbgAssign(&StoreLikeInst, Val, VarRec.Var, Expr, Dest,
-                                    AddrExpr, VarRec.DL);
+  auto *Assign = DbgVariableRecord::createLinkedDVRAssign(
+      &StoreLikeInst, Val, VarRec.Var, Expr, Dest, AddrExpr, VarRec.DL);
   (void)Assign;
-  LLVM_DEBUG(if (!Assign.isNull()) {
-    if (const auto *Record = dyn_cast<DbgRecord *>(Assign))
-      errs() << " > INSERT: " << *Record << "\n";
-    else
-      errs() << " > INSERT: " << *cast<Instruction *>(Assign) << "\n";
-  });
+  LLVM_DEBUG(if (Assign) errs() << " > INSERT: " << *Assign << "\n");
+  return;
 }
 
 #undef DEBUG_TYPE // Silence redefinition warning (from ConstantsContext.h).

llvm/lib/Transforms/Utils/LoopUtils.cpp

@@ -606,7 +606,6 @@ void llvm::deleteDeadLoop(Loop *L, DominatorTree *DT, ScalarEvolution *SE,
 
   // Use a map to unique and a vector to guarantee deterministic ordering.
   llvm::SmallDenseSet<DebugVariable, 4> DeadDebugSet;
-  llvm::SmallVector<DbgVariableIntrinsic *, 4> DeadDebugInst;
   llvm::SmallVector<DbgVariableRecord *, 4> DeadDbgVariableRecords;
 
   if (ExitBlock) {
@@ -633,29 +632,19 @@ void llvm::deleteDeadLoop(Loop *L, DominatorTree *DT, ScalarEvolution *SE,
           U.set(Poison);
         }
 
-        // RemoveDIs: do the same as below for DbgVariableRecords.
-        if (Block->IsNewDbgInfoFormat) {
-          for (DbgVariableRecord &DVR : llvm::make_early_inc_range(
-                   filterDbgVars(I.getDbgRecordRange()))) {
-            DebugVariable Key(DVR.getVariable(), DVR.getExpression(),
-                              DVR.getDebugLoc().get());
-            if (!DeadDebugSet.insert(Key).second)
-              continue;
-            // Unlinks the DVR from it's container, for later insertion.
-            DVR.removeFromParent();
-            DeadDbgVariableRecords.push_back(&DVR);
-          }
-        }
-
-        // For one of each variable encountered, preserve a debug intrinsic (set
+        // For one of each variable encountered, preserve a debug record (set
         // to Poison) and transfer it to the loop exit. This terminates any
         // variable locations that were set during the loop.
-        auto *DVI = dyn_cast<DbgVariableIntrinsic>(&I);
-        if (!DVI)
-          continue;
-        if (!DeadDebugSet.insert(DebugVariable(DVI)).second)
-          continue;
-        DeadDebugInst.push_back(DVI);
+        for (DbgVariableRecord &DVR :
+             llvm::make_early_inc_range(filterDbgVars(I.getDbgRecordRange()))) {
+          DebugVariable Key(DVR.getVariable(), DVR.getExpression(),
+                            DVR.getDebugLoc().get());
+          if (!DeadDebugSet.insert(Key).second)
+            continue;
+          // Unlinks the DVR from it's container, for later insertion.
+          DVR.removeFromParent();
+          DeadDbgVariableRecords.push_back(&DVR);
+        }
       }
 
     // After the loop has been deleted all the values defined and modified
@@ -671,9 +660,6 @@ void llvm::deleteDeadLoop(Loop *L, DominatorTree *DT, ScalarEvolution *SE,
            "There should be a non-PHI instruction in exit block, else these "
            "instructions will have no parent.");
 
-    for (auto *DVI : DeadDebugInst)
-      DVI->moveBefore(*ExitBlock, InsertDbgValueBefore);
-
     // Due to the "head" bit in BasicBlock::iterator, we're going to insert
     // each DbgVariableRecord right at the start of the block, wheras dbg.values
     // would be repeatedly inserted before the first instruction. To replicate

llvm/unittests/IR/IRBuilderTest.cpp

@@ -1003,18 +1003,8 @@ TEST_F(IRBuilderTest, DIBuilder) {
     EXPECT_TRUE(verifyModule(*M));
   };
 
-  // Test in new-debug mode.
-  EXPECT_TRUE(M->IsNewDbgInfoFormat);
   RunTest();
-
-  // Test in old-debug mode.
-  // Reset the test then call convertFromNewDbgValues to flip the flag
-  // on the test's Module, Function and BasicBlock.
   TearDown();
-  SetUp();
-  M->convertFromNewDbgValues();
-  EXPECT_FALSE(M->IsNewDbgInfoFormat);
-  RunTest();
 }
 
 TEST_F(IRBuilderTest, createArtificialSubprogram) {