1 files changed, 61 insertions, 52 deletions

diff --git a/contrib/llvm-project/llvm/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp b/contrib/llvm-project/llvm/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
index 9af39d9a0dd1..3631733713ab 100644
--- a/contrib/llvm-project/llvm/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
+++ b/contrib/llvm-project/llvm/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
@@ -6,10 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This pass is used to ensure that functions have at most one return
-// instruction in them.  Additionally, it keeps track of which node is the new
-// exit node of the CFG.  If there are no exit nodes in the CFG, the getExitNode
-// method will return a null pointer.
+// This pass is used to ensure that functions have at most one return and one
+// unreachable instruction in them.
 //
 //===----------------------------------------------------------------------===//
 
@@ -22,73 +20,66 @@
 #include "llvm/Transforms/Utils.h"
 using namespace llvm;
 
-char UnifyFunctionExitNodes::ID = 0;
+char UnifyFunctionExitNodesLegacyPass::ID = 0;
 
-UnifyFunctionExitNodes::UnifyFunctionExitNodes() : FunctionPass(ID) {
-  initializeUnifyFunctionExitNodesPass(*PassRegistry::getPassRegistry());
+UnifyFunctionExitNodesLegacyPass::UnifyFunctionExitNodesLegacyPass()
+    : FunctionPass(ID) {
+  initializeUnifyFunctionExitNodesLegacyPassPass(
+      *PassRegistry::getPassRegistry());
 }
 
-INITIALIZE_PASS(UnifyFunctionExitNodes, "mergereturn",
+INITIALIZE_PASS(UnifyFunctionExitNodesLegacyPass, "mergereturn",
                 "Unify function exit nodes", false, false)
 
 Pass *llvm::createUnifyFunctionExitNodesPass() {
-  return new UnifyFunctionExitNodes();
+  return new UnifyFunctionExitNodesLegacyPass();
 }
 
-void UnifyFunctionExitNodes::getAnalysisUsage(AnalysisUsage &AU) const{
+void UnifyFunctionExitNodesLegacyPass::getAnalysisUsage(
+    AnalysisUsage &AU) const {
   // We preserve the non-critical-edgeness property
   AU.addPreservedID(BreakCriticalEdgesID);
   // This is a cluster of orthogonal Transforms
   AU.addPreservedID(LowerSwitchID);
 }
 
-// UnifyAllExitNodes - Unify all exit nodes of the CFG by creating a new
-// BasicBlock, and converting all returns to unconditional branches to this
-// new basic block.  The singular exit node is returned.
-//
-// If there are no return stmts in the Function, a null pointer is returned.
-//
-bool UnifyFunctionExitNodes::runOnFunction(Function &F) {
-  // Loop over all of the blocks in a function, tracking all of the blocks that
-  // return.
-  //
-  std::vector<BasicBlock*> ReturningBlocks;
-  std::vector<BasicBlock*> UnreachableBlocks;
+namespace {
+
+bool unifyUnreachableBlocks(Function &F) {
+  std::vector<BasicBlock *> UnreachableBlocks;
+
   for (BasicBlock &I : F)
-    if (isa<ReturnInst>(I.getTerminator()))
-      ReturningBlocks.push_back(&I);
-    else if (isa<UnreachableInst>(I.getTerminator()))
+    if (isa<UnreachableInst>(I.getTerminator()))
       UnreachableBlocks.push_back(&I);
 
-  // Then unreachable blocks.
-  if (UnreachableBlocks.empty()) {
-    UnreachableBlock = nullptr;
-  } else if (UnreachableBlocks.size() == 1) {
-    UnreachableBlock = UnreachableBlocks.front();
-  } else {
-    UnreachableBlock = BasicBlock::Create(F.getContext(),
-                                          "UnifiedUnreachableBlock", &F);
-    new UnreachableInst(F.getContext(), UnreachableBlock);
-
-    for (BasicBlock *BB : UnreachableBlocks) {
-      BB->getInstList().pop_back();  // Remove the unreachable inst.
-      BranchInst::Create(UnreachableBlock, BB);
-    }
+  if (UnreachableBlocks.size() <= 1)
+    return false;
+
+  BasicBlock *UnreachableBlock =
+      BasicBlock::Create(F.getContext(), "UnifiedUnreachableBlock", &F);
+  new UnreachableInst(F.getContext(), UnreachableBlock);
+
+  for (BasicBlock *BB : UnreachableBlocks) {
+    BB->getInstList().pop_back(); // Remove the unreachable inst.
+    BranchInst::Create(UnreachableBlock, BB);
   }
 
-  // Now handle return blocks.
-  if (ReturningBlocks.empty()) {
-    ReturnBlock = nullptr;
-    return false;                          // No blocks return
-  } else if (ReturningBlocks.size() == 1) {
-    ReturnBlock = ReturningBlocks.front(); // Already has a single return block
+  return true;
+}
+
+bool unifyReturnBlocks(Function &F) {
+  std::vector<BasicBlock *> ReturningBlocks;
+
+  for (BasicBlock &I : F)
+    if (isa<ReturnInst>(I.getTerminator()))
+      ReturningBlocks.push_back(&I);
+
+  if (ReturningBlocks.size() <= 1)
     return false;
-  }
 
-  // Otherwise, we need to insert a new basic block into the function, add a PHI
-  // nodes (if the function returns values), and convert all of the return
-  // instructions into unconditional branches.
-  //
+  // Insert a new basic block into the function, add PHI nodes (if the function
+  // returns values), and convert all of the return instructions into
+  // unconditional branches.
   BasicBlock *NewRetBlock = BasicBlock::Create(F.getContext(),
                                                "UnifiedReturnBlock", &F);
 
@@ -105,7 +96,6 @@ bool UnifyFunctionExitNodes::runOnFunction(Function &F) {
 
   // Loop over all of the blocks, replacing the return instruction with an
   // unconditional branch.
-  //
   for (BasicBlock *BB : ReturningBlocks) {
     // Add an incoming element to the PHI node for every return instruction that
     // is merging into this new block...
@@ -115,6 +105,25 @@ bool UnifyFunctionExitNodes::runOnFunction(Function &F) {
     BB->getInstList().pop_back();  // Remove the return insn
     BranchInst::Create(NewRetBlock, BB);
   }
-  ReturnBlock = NewRetBlock;
+
   return true;
 }
+} // namespace
+
+// Unify all exit nodes of the CFG by creating a new BasicBlock, and converting
+// all returns to unconditional branches to this new basic block. Also, unify
+// all unreachable blocks.
+bool UnifyFunctionExitNodesLegacyPass::runOnFunction(Function &F) {
+  bool Changed = false;
+  Changed |= unifyUnreachableBlocks(F);
+  Changed |= unifyReturnBlocks(F);
+  return Changed;
+}
+
+PreservedAnalyses UnifyFunctionExitNodesPass::run(Function &F,
+                                                  FunctionAnalysisManager &AM) {
+  bool Changed = false;
+  Changed |= unifyUnreachableBlocks(F);
+  Changed |= unifyReturnBlocks(F);
+  return Changed ? PreservedAnalyses() : PreservedAnalyses::all();
+}