1 files changed, 94 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Utils/EscapeEnumerator.cpp b/llvm/lib/Transforms/Utils/EscapeEnumerator.cpp
new file mode 100644
index 000000000000..914babeb6829
--- /dev/null
+++ b/llvm/lib/Transforms/Utils/EscapeEnumerator.cpp
@@ -0,0 +1,94 @@
+//===- EscapeEnumerator.cpp -----------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Defines a helper class that enumerates all possible exits from a function,
+// including exception handling.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/EscapeEnumerator.h"
+#include "llvm/Analysis/EHPersonalities.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/IR/CallSite.h"
+#include "llvm/IR/Module.h"
+using namespace llvm;
+
+static FunctionCallee getDefaultPersonalityFn(Module *M) {
+  LLVMContext &C = M->getContext();
+  Triple T(M->getTargetTriple());
+  EHPersonality Pers = getDefaultEHPersonality(T);
+  return M->getOrInsertFunction(getEHPersonalityName(Pers),
+                                FunctionType::get(Type::getInt32Ty(C), true));
+}
+
+IRBuilder<> *EscapeEnumerator::Next() {
+  if (Done)
+    return nullptr;
+
+  // Find all 'return', 'resume', and 'unwind' instructions.
+  while (StateBB != StateE) {
+    BasicBlock *CurBB = &*StateBB++;
+
+    // Branches and invokes do not escape, only unwind, resume, and return
+    // do.
+    Instruction *TI = CurBB->getTerminator();
+    if (!isa<ReturnInst>(TI) && !isa<ResumeInst>(TI))
+      continue;
+
+    Builder.SetInsertPoint(TI);
+    return &Builder;
+  }
+
+  Done = true;
+
+  if (!HandleExceptions)
+    return nullptr;
+
+  if (F.doesNotThrow())
+    return nullptr;
+
+  // Find all 'call' instructions that may throw.
+  SmallVector<Instruction *, 16> Calls;
+  for (BasicBlock &BB : F)
+    for (Instruction &II : BB)
+      if (CallInst *CI = dyn_cast<CallInst>(&II))
+        if (!CI->doesNotThrow())
+          Calls.push_back(CI);
+
+  if (Calls.empty())
+    return nullptr;
+
+  // Create a cleanup block.
+  LLVMContext &C = F.getContext();
+  BasicBlock *CleanupBB = BasicBlock::Create(C, CleanupBBName, &F);
+  Type *ExnTy = StructType::get(Type::getInt8PtrTy(C), Type::getInt32Ty(C));
+  if (!F.hasPersonalityFn()) {
+    FunctionCallee PersFn = getDefaultPersonalityFn(F.getParent());
+    F.setPersonalityFn(cast<Constant>(PersFn.getCallee()));
+  }
+
+  if (isScopedEHPersonality(classifyEHPersonality(F.getPersonalityFn()))) {
+    report_fatal_error("Scoped EH not supported");
+  }
+
+  LandingPadInst *LPad =
+      LandingPadInst::Create(ExnTy, 1, "cleanup.lpad", CleanupBB);
+  LPad->setCleanup(true);
+  ResumeInst *RI = ResumeInst::Create(LPad, CleanupBB);
+
+  // Transform the 'call' instructions into 'invoke's branching to the
+  // cleanup block. Go in reverse order to make prettier BB names.
+  SmallVector<Value *, 16> Args;
+  for (unsigned I = Calls.size(); I != 0;) {
+    CallInst *CI = cast<CallInst>(Calls[--I]);
+    changeToInvokeAndSplitBasicBlock(CI, CleanupBB);
+  }
+
+  Builder.SetInsertPoint(RI);
+  return &Builder;
+}