[NFC][RemoveDIs] Provide an iterator-taking split-block method

jmorse · jmorse · commit 1d82c765eff0 · 2023-09-11T17:50:47.000+01:00
As per the stack of patches this is attached to, allow users of BasicBlock::splitBasicBlock to provide an iterator for a position, instead of just an instruction pointer. This is to fit with my proposal for how to get rid of debug intrinsics [0]. There are other call-sites that would need to change, but this is sufficient for a stage2clang self host and some other C++ projects to build identical binaries, in the context of the whole remove-DIs project. [0] https://discourse.llvm.org/t/rfc-instruction-api-changes-needed-to-eliminate-debug-intrinsics-from-ir/68939 Differential Revision: https://reviews.llvm.org/D152545
diff --git a/llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h b/llvm/include/llvm/Transforms/Utils/BasicBlockUtils.h
@@ -280,10 +280,16 @@ BasicBlock *ehAwareSplitEdge(BasicBlock *BB, BasicBlock *Succ,
 /// branch. The new block with name \p BBName is returned.
 ///
 /// FIXME: deprecated, switch to the DomTreeUpdater-based one.
-BasicBlock *SplitBlock(BasicBlock *Old, Instruction *SplitPt, DominatorTree *DT,
+BasicBlock *SplitBlock(BasicBlock *Old, BasicBlock::iterator SplitPt, DominatorTree *DT,
                        LoopInfo *LI = nullptr,
                        MemorySSAUpdater *MSSAU = nullptr,
                        const Twine &BBName = "", bool Before = false);
+inline BasicBlock *SplitBlock(BasicBlock *Old, Instruction *SplitPt, DominatorTree *DT,
+                       LoopInfo *LI = nullptr,
+                       MemorySSAUpdater *MSSAU = nullptr,
+                       const Twine &BBName = "", bool Before = false) {
+  return SplitBlock(Old, SplitPt->getIterator(), DT, LI, MSSAU, BBName, Before);
+}
 
 /// Split the specified block at the specified instruction.
 ///
@@ -293,19 +299,30 @@ BasicBlock *SplitBlock(BasicBlock *Old, Instruction *SplitPt, DominatorTree *DT,
 /// Everything before \p SplitPt stays in \p Old and everything starting with \p
 /// SplitPt moves to a new block. The two blocks are joined by an unconditional
 /// branch. The new block with name \p BBName is returned.
-BasicBlock *SplitBlock(BasicBlock *Old, Instruction *SplitPt,
+BasicBlock *SplitBlock(BasicBlock *Old, BasicBlock::iterator SplitPt,
                        DomTreeUpdater *DTU = nullptr, LoopInfo *LI = nullptr,
                        MemorySSAUpdater *MSSAU = nullptr,
                        const Twine &BBName = "", bool Before = false);
+inline BasicBlock *SplitBlock(BasicBlock *Old, Instruction *SplitPt,
+                       DomTreeUpdater *DTU = nullptr, LoopInfo *LI = nullptr,
+                       MemorySSAUpdater *MSSAU = nullptr,
+                       const Twine &BBName = "", bool Before = false) {
+  return SplitBlock(Old, SplitPt->getIterator(), DTU, LI, MSSAU, BBName, Before);
+}
 
 /// Split the specified block at the specified instruction \p SplitPt.
 /// All instructions before \p SplitPt are moved to a new block and all
 /// instructions after \p SplitPt stay in the old block. The new block and the
 /// old block are joined by inserting an unconditional branch to the end of the
 /// new block. The new block with name \p BBName is returned.
-BasicBlock *splitBlockBefore(BasicBlock *Old, Instruction *SplitPt,
+BasicBlock *splitBlockBefore(BasicBlock *Old, BasicBlock::iterator SplitPt,
                              DomTreeUpdater *DTU, LoopInfo *LI,
                              MemorySSAUpdater *MSSAU, const Twine &BBName = "");
+inline BasicBlock *splitBlockBefore(BasicBlock *Old, Instruction *SplitPt,
+                             DomTreeUpdater *DTU, LoopInfo *LI,
+                             MemorySSAUpdater *MSSAU, const Twine &BBName = "") {
+  return splitBlockBefore(Old, SplitPt->getIterator(), DTU, LI, MSSAU, BBName);
+}
 
 /// This method introduces at least one new basic block into the function and
 /// moves some of the predecessors of BB to be predecessors of the new block.
@@ -417,22 +434,44 @@ ReturnInst *FoldReturnIntoUncondBranch(ReturnInst *RI, BasicBlock *BB,
 /// Returns the NewBasicBlock's terminator.
 ///
 /// Updates DTU and LI if given.
-Instruction *SplitBlockAndInsertIfThen(Value *Cond, Instruction *SplitBefore,
+Instruction *SplitBlockAndInsertIfThen(Value *Cond, BasicBlock::iterator SplitBefore,
                                        bool Unreachable,
                                        MDNode *BranchWeights = nullptr,
                                        DomTreeUpdater *DTU = nullptr,
                                        LoopInfo *LI = nullptr,
                                        BasicBlock *ThenBlock = nullptr);
 
+inline Instruction *SplitBlockAndInsertIfThen(Value *Cond, Instruction *SplitBefore,
+                                       bool Unreachable,
+                                       MDNode *BranchWeights = nullptr,
+                                       DomTreeUpdater *DTU = nullptr,
+                                       LoopInfo *LI = nullptr,
+                                       BasicBlock *ThenBlock = nullptr) {
+  return SplitBlockAndInsertIfThen(Cond, SplitBefore->getIterator(),
+                                   Unreachable, BranchWeights, DTU, LI,
+                                   ThenBlock);
+}
+
 /// Similar to SplitBlockAndInsertIfThen, but the inserted block is on the false
 /// path of the branch.
-Instruction *SplitBlockAndInsertIfElse(Value *Cond, Instruction *SplitBefore,
+Instruction *SplitBlockAndInsertIfElse(Value *Cond, BasicBlock::iterator SplitBefore,
                                        bool Unreachable,
                                        MDNode *BranchWeights = nullptr,
                                        DomTreeUpdater *DTU = nullptr,
                                        LoopInfo *LI = nullptr,
                                        BasicBlock *ElseBlock = nullptr);
 
+inline Instruction *SplitBlockAndInsertIfElse(Value *Cond, Instruction *SplitBefore,
+                                       bool Unreachable,
+                                       MDNode *BranchWeights = nullptr,
+                                       DomTreeUpdater *DTU = nullptr,
+                                       LoopInfo *LI = nullptr,
+                                       BasicBlock *ElseBlock = nullptr) {
+  return SplitBlockAndInsertIfElse(Cond, SplitBefore->getIterator(),
+                                   Unreachable, BranchWeights, DTU, LI,
+                                   ElseBlock);
+}
+
 /// SplitBlockAndInsertIfThenElse is similar to SplitBlockAndInsertIfThen,
 /// but also creates the ElseBlock.
 /// Before:
@@ -449,13 +488,25 @@ Instruction *SplitBlockAndInsertIfElse(Value *Cond, Instruction *SplitBefore,
 ///   Tail
 ///
 /// Updates DT if given.
-void SplitBlockAndInsertIfThenElse(Value *Cond, Instruction *SplitBefore,
+void SplitBlockAndInsertIfThenElse(Value *Cond,
+                                   BasicBlock::iterator SplitBefore,
                                    Instruction **ThenTerm,
                                    Instruction **ElseTerm,
                                    MDNode *BranchWeights = nullptr,
                                    DomTreeUpdater *DTU = nullptr,
                                    LoopInfo *LI = nullptr);
 
+inline void SplitBlockAndInsertIfThenElse(Value *Cond, Instruction *SplitBefore,
+                                   Instruction **ThenTerm,
+                                   Instruction **ElseTerm,
+                                   MDNode *BranchWeights = nullptr,
+                                   DomTreeUpdater *DTU = nullptr,
+                                   LoopInfo *LI = nullptr)
+{
+  SplitBlockAndInsertIfThenElse(Cond, SplitBefore->getIterator(), ThenTerm,
+                               ElseTerm, BranchWeights, DTU, LI);
+}
+
 /// Split the containing block at the specified instruction - everything before
 /// SplitBefore stays in the old basic block, and the rest of the instructions
 /// in the BB are moved to a new block. The two blocks are connected by a
@@ -483,7 +534,8 @@ void SplitBlockAndInsertIfThenElse(Value *Cond, Instruction *SplitBefore,
 /// caller must ensure that Tail is reachable from Head.
 /// Returns the newly created blocks in \p ThenBlock and \p ElseBlock.
 /// Updates DTU and LI if given.
-void SplitBlockAndInsertIfThenElse(Value *Cond, Instruction *SplitBefore,
+void SplitBlockAndInsertIfThenElse(Value *Cond,
+                                   BasicBlock::iterator SplitBefore,
                                    BasicBlock **ThenBlock,
                                    BasicBlock **ElseBlock,
                                    bool UnreachableThen = false,
@@ -492,6 +544,18 @@ void SplitBlockAndInsertIfThenElse(Value *Cond, Instruction *SplitBefore,
                                    DomTreeUpdater *DTU = nullptr,
                                    LoopInfo *LI = nullptr);
 
+inline void SplitBlockAndInsertIfThenElse(Value *Cond, Instruction *SplitBefore,
+                                   BasicBlock **ThenBlock,
+                                   BasicBlock **ElseBlock,
+                                   bool UnreachableThen = false,
+                                   bool UnreachableElse = false,
+                                   MDNode *BranchWeights = nullptr,
+                                   DomTreeUpdater *DTU = nullptr,
+                                   LoopInfo *LI = nullptr) {
+  SplitBlockAndInsertIfThenElse(Cond, SplitBefore->getIterator(), ThenBlock,
+    ElseBlock, UnreachableThen, UnreachableElse, BranchWeights, DTU, LI);
+}
+
 /// Insert a for (int i = 0; i < End; i++) loop structure (with the exception
 /// that \p End is assumed > 0, and thus not checked on entry) at \p
 /// SplitBefore.  Returns the first insert point in the loop body, and the
diff --git a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
@@ -610,7 +610,7 @@ static bool unswitchTrivialBranch(Loop &L, BranchInst &BI, DominatorTree &DT,
     UnswitchedBB = LoopExitBB;
   } else {
     UnswitchedBB =
-        SplitBlock(LoopExitBB, &LoopExitBB->front(), &DT, &LI, MSSAU);
+        SplitBlock(LoopExitBB, LoopExitBB->begin(), &DT, &LI, MSSAU, "", false);
   }
 
   if (MSSAU && VerifyMemorySSA)
@@ -883,7 +883,7 @@ static bool unswitchTrivialSwitch(Loop &L, SwitchInst &SI, DominatorTree &DT,
       rewritePHINodesForUnswitchedExitBlock(*DefaultExitBB, *ParentBB, *OldPH);
     } else {
       auto *SplitBB =
-          SplitBlock(DefaultExitBB, &DefaultExitBB->front(), &DT, &LI, MSSAU);
+          SplitBlock(DefaultExitBB, DefaultExitBB->begin(), &DT, &LI, MSSAU);
       rewritePHINodesForExitAndUnswitchedBlocks(*DefaultExitBB, *SplitBB,
                                                 *ParentBB, *OldPH,
                                                 /*FullUnswitch*/ true);
@@ -910,7 +910,7 @@ static bool unswitchTrivialSwitch(Loop &L, SwitchInst &SI, DominatorTree &DT,
     BasicBlock *&SplitExitBB = SplitExitBBMap[ExitBB];
     if (!SplitExitBB) {
       // If this is the first time we see this, do the split and remember it.
-      SplitExitBB = SplitBlock(ExitBB, &ExitBB->front(), &DT, &LI, MSSAU);
+      SplitExitBB = SplitBlock(ExitBB, ExitBB->begin(), &DT, &LI, MSSAU);
       rewritePHINodesForExitAndUnswitchedBlocks(*ExitBB, *SplitExitBB,
                                                 *ParentBB, *OldPH,
                                                 /*FullUnswitch*/ true);
@@ -1211,7 +1211,7 @@ static BasicBlock *buildClonedLoopBlocks(
     // place to merge the CFG, so split the exit first. This is always safe to
     // do because there cannot be any non-loop predecessors of a loop exit in
     // loop simplified form.
-    auto *MergeBB = SplitBlock(ExitBB, &ExitBB->front(), &DT, &LI, MSSAU);
+    auto *MergeBB = SplitBlock(ExitBB, ExitBB->begin(), &DT, &LI, MSSAU);
 
     // Rearrange the names to make it easier to write test cases by having the
     // exit block carry the suffix rather than the merge block carrying the
diff --git a/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp b/llvm/lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -879,7 +879,7 @@ llvm::SplitAllCriticalEdges(Function &F,
   return NumBroken;
 }
 
-static BasicBlock *SplitBlockImpl(BasicBlock *Old, Instruction *SplitPt,
+static BasicBlock *SplitBlockImpl(BasicBlock *Old, BasicBlock::iterator SplitPt,
                                   DomTreeUpdater *DTU, DominatorTree *DT,
                                   LoopInfo *LI, MemorySSAUpdater *MSSAU,
                                   const Twine &BBName, bool Before) {
@@ -889,7 +889,7 @@ static BasicBlock *SplitBlockImpl(BasicBlock *Old, Instruction *SplitPt,
                             DTU ? DTU : (DT ? &LocalDTU : nullptr), LI, MSSAU,
                             BBName);
   }
-  BasicBlock::iterator SplitIt = SplitPt->getIterator();
+  BasicBlock::iterator SplitIt = SplitPt;
   while (isa<PHINode>(SplitIt) || SplitIt->isEHPad()) {
     ++SplitIt;
     assert(SplitIt != SplitPt->getParent()->end());
@@ -935,27 +935,27 @@ static BasicBlock *SplitBlockImpl(BasicBlock *Old, Instruction *SplitPt,
   return New;
 }
 
-BasicBlock *llvm::SplitBlock(BasicBlock *Old, Instruction *SplitPt,
+BasicBlock *llvm::SplitBlock(BasicBlock *Old, BasicBlock::iterator SplitPt,
                              DominatorTree *DT, LoopInfo *LI,
                              MemorySSAUpdater *MSSAU, const Twine &BBName,
                              bool Before) {
   return SplitBlockImpl(Old, SplitPt, /*DTU=*/nullptr, DT, LI, MSSAU, BBName,
                         Before);
 }
-BasicBlock *llvm::SplitBlock(BasicBlock *Old, Instruction *SplitPt,
+BasicBlock *llvm::SplitBlock(BasicBlock *Old, BasicBlock::iterator SplitPt,
                              DomTreeUpdater *DTU, LoopInfo *LI,
                              MemorySSAUpdater *MSSAU, const Twine &BBName,
                              bool Before) {
   return SplitBlockImpl(Old, SplitPt, DTU, /*DT=*/nullptr, LI, MSSAU, BBName,
                         Before);
 }
 
-BasicBlock *llvm::splitBlockBefore(BasicBlock *Old, Instruction *SplitPt,
+BasicBlock *llvm::splitBlockBefore(BasicBlock *Old, BasicBlock::iterator SplitPt,
                                    DomTreeUpdater *DTU, LoopInfo *LI,
                                    MemorySSAUpdater *MSSAU,
                                    const Twine &BBName) {
 
-  BasicBlock::iterator SplitIt = SplitPt->getIterator();
+  BasicBlock::iterator SplitIt = SplitPt;
   while (isa<PHINode>(SplitIt) || SplitIt->isEHPad())
     ++SplitIt;
   std::string Name = BBName.str();
@@ -1471,7 +1471,7 @@ ReturnInst *llvm::FoldReturnIntoUncondBranch(ReturnInst *RI, BasicBlock *BB,
 }
 
 Instruction *llvm::SplitBlockAndInsertIfThen(Value *Cond,
-                                             Instruction *SplitBefore,
+                                             BasicBlock::iterator SplitBefore,
                                              bool Unreachable,
                                              MDNode *BranchWeights,
                                              DomTreeUpdater *DTU, LoopInfo *LI,
@@ -1484,7 +1484,7 @@ Instruction *llvm::SplitBlockAndInsertIfThen(Value *Cond,
 }
 
 Instruction *llvm::SplitBlockAndInsertIfElse(Value *Cond,
-                                             Instruction *SplitBefore,
+                                             BasicBlock::iterator SplitBefore,
                                              bool Unreachable,
                                              MDNode *BranchWeights,
                                              DomTreeUpdater *DTU, LoopInfo *LI,
@@ -1496,7 +1496,7 @@ Instruction *llvm::SplitBlockAndInsertIfElse(Value *Cond,
   return ElseBlock->getTerminator();
 }
 
-void llvm::SplitBlockAndInsertIfThenElse(Value *Cond, Instruction *SplitBefore,
+void llvm::SplitBlockAndInsertIfThenElse(Value *Cond, BasicBlock::iterator SplitBefore,
                                          Instruction **ThenTerm,
                                          Instruction **ElseTerm,
                                          MDNode *BranchWeights,
@@ -1512,7 +1512,7 @@ void llvm::SplitBlockAndInsertIfThenElse(Value *Cond, Instruction *SplitBefore,
 }
 
 void llvm::SplitBlockAndInsertIfThenElse(
-    Value *Cond, Instruction *SplitBefore, BasicBlock **ThenBlock,
+    Value *Cond, BasicBlock::iterator SplitBefore, BasicBlock **ThenBlock,
     BasicBlock **ElseBlock, bool UnreachableThen, bool UnreachableElse,
     MDNode *BranchWeights, DomTreeUpdater *DTU, LoopInfo *LI) {
   assert((ThenBlock || ElseBlock) &&
@@ -1529,7 +1529,7 @@ void llvm::SplitBlockAndInsertIfThenElse(
   }
 
   LLVMContext &C = Head->getContext();
-  BasicBlock *Tail = Head->splitBasicBlock(SplitBefore->getIterator());
+  BasicBlock *Tail = Head->splitBasicBlock(SplitBefore);
   BasicBlock *TrueBlock = Tail;
   BasicBlock *FalseBlock = Tail;
   bool ThenToTailEdge = false;
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -4015,9 +4015,11 @@ static bool mergeConditionalStoreToAddress(
     QPred = QB.CreateNot(QPred);
   Value *CombinedPred = QB.CreateOr(PPred, QPred);
 
-  auto *T = SplitBlockAndInsertIfThen(CombinedPred, &*QB.GetInsertPoint(),
+  BasicBlock::iterator InsertPt = QB.GetInsertPoint();
+  auto *T = SplitBlockAndInsertIfThen(CombinedPred, InsertPt,
                                       /*Unreachable=*/false,
                                       /*BranchWeights=*/nullptr, DTU);
+
   QB.SetInsertPoint(T);
   StoreInst *SI = cast<StoreInst>(QB.CreateStore(QPHI, Address));
   SI->setAAMetadata(PStore->getAAMetadata().merge(QStore->getAAMetadata()));
