1 files changed, 183 insertions, 0 deletions
diff --git a/contrib/llvm/lib/CodeGen/DwarfEHPrepare.cpp b/contrib/llvm/lib/CodeGen/DwarfEHPrepare.cpp
new file mode 100644
index 0000000..f27ec77
--- /dev/null
+++ b/contrib/llvm/lib/CodeGen/DwarfEHPrepare.cpp
@@ -0,0 +1,183 @@
+//===-- DwarfEHPrepare - Prepare exception handling for code generation ---===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass mulches exception handling code into a form adapted to code
+// generation. Required if using dwarf exception handling.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "dwarfehprepare"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Module.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/CallSite.h"
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/SSAUpdater.h"
+using namespace llvm;
+
+STATISTIC(NumResumesLowered, "Number of resume calls lowered");
+
+namespace {
+  class DwarfEHPrepare : public FunctionPass {
+    const TargetMachine *TM;
+    const TargetLoweringBase *TLI;
+
+    // RewindFunction - _Unwind_Resume or the target equivalent.
+    Constant *RewindFunction;
+
+    bool InsertUnwindResumeCalls(Function &Fn);
+    Value *GetExceptionObject(ResumeInst *RI);
+
+  public:
+    static char ID; // Pass identification, replacement for typeid.
+    DwarfEHPrepare(const TargetMachine *tm) :
+      FunctionPass(ID), TM(tm), TLI(TM->getTargetLowering()),
+      RewindFunction(0) {
+        initializeDominatorTreePass(*PassRegistry::getPassRegistry());
+      }
+
+    virtual bool runOnFunction(Function &Fn);
+
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const { }
+
+    const char *getPassName() const {
+      return "Exception handling preparation";
+    }
+  };
+} // end anonymous namespace
+
+char DwarfEHPrepare::ID = 0;
+
+FunctionPass *llvm::createDwarfEHPass(const TargetMachine *tm) {
+  return new DwarfEHPrepare(tm);
+}
+
+/// GetExceptionObject - Return the exception object from the value passed into
+/// the 'resume' instruction (typically an aggregate). Clean up any dead
+/// instructions, including the 'resume' instruction.
+Value *DwarfEHPrepare::GetExceptionObject(ResumeInst *RI) {
+  Value *V = RI->getOperand(0);
+  Value *ExnObj = 0;
+  InsertValueInst *SelIVI = dyn_cast<InsertValueInst>(V);
+  LoadInst *SelLoad = 0;
+  InsertValueInst *ExcIVI = 0;
+  bool EraseIVIs = false;
+
+  if (SelIVI) {
+    if (SelIVI->getNumIndices() == 1 && *SelIVI->idx_begin() == 1) {
+      ExcIVI = dyn_cast<InsertValueInst>(SelIVI->getOperand(0));
+      if (ExcIVI && isa<UndefValue>(ExcIVI->getOperand(0)) &&
+          ExcIVI->getNumIndices() == 1 && *ExcIVI->idx_begin() == 0) {
+        ExnObj = ExcIVI->getOperand(1);
+        SelLoad = dyn_cast<LoadInst>(SelIVI->getOperand(1));
+        EraseIVIs = true;
+      }
+    }
+  }
+
+  if (!ExnObj)
+    ExnObj = ExtractValueInst::Create(RI->getOperand(0), 0, "exn.obj", RI);
+
+  RI->eraseFromParent();
+
+  if (EraseIVIs) {
+    if (SelIVI->getNumUses() == 0)
+      SelIVI->eraseFromParent();
+    if (ExcIVI->getNumUses() == 0)
+      ExcIVI->eraseFromParent();
+    if (SelLoad && SelLoad->getNumUses() == 0)
+      SelLoad->eraseFromParent();
+  }
+
+  return ExnObj;
+}
+
+/// InsertUnwindResumeCalls - Convert the ResumeInsts that are still present
+/// into calls to the appropriate _Unwind_Resume function.
+bool DwarfEHPrepare::InsertUnwindResumeCalls(Function &Fn) {
+  bool UsesNewEH = false;
+  SmallVector<ResumeInst*, 16> Resumes;
+  for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
+    TerminatorInst *TI = I->getTerminator();
+    if (ResumeInst *RI = dyn_cast<ResumeInst>(TI))
+      Resumes.push_back(RI);
+    else if (InvokeInst *II = dyn_cast<InvokeInst>(TI))
+      UsesNewEH = II->getUnwindDest()->isLandingPad();
+  }
+
+  if (Resumes.empty())
+    return UsesNewEH;
+
+  // Find the rewind function if we didn't already.
+  if (!RewindFunction) {
+    LLVMContext &Ctx = Resumes[0]->getContext();
+    FunctionType *FTy = FunctionType::get(Type::getVoidTy(Ctx),
+                                          Type::getInt8PtrTy(Ctx), false);
+    const char *RewindName = TLI->getLibcallName(RTLIB::UNWIND_RESUME);
+    RewindFunction = Fn.getParent()->getOrInsertFunction(RewindName, FTy);
+  }
+
+  // Create the basic block where the _Unwind_Resume call will live.
+  LLVMContext &Ctx = Fn.getContext();
+  unsigned ResumesSize = Resumes.size();
+
+  if (ResumesSize == 1) {
+    // Instead of creating a new BB and PHI node, just append the call to
+    // _Unwind_Resume to the end of the single resume block.
+    ResumeInst *RI = Resumes.front();
+    BasicBlock *UnwindBB = RI->getParent();
+    Value *ExnObj = GetExceptionObject(RI);
+
+    // Call the _Unwind_Resume function.
+    CallInst *CI = CallInst::Create(RewindFunction, ExnObj, "", UnwindBB);
+    CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));
+
+    // We never expect _Unwind_Resume to return.
+    new UnreachableInst(Ctx, UnwindBB);
+    return true;
+  }
+
+  BasicBlock *UnwindBB = BasicBlock::Create(Ctx, "unwind_resume", &Fn);
+  PHINode *PN = PHINode::Create(Type::getInt8PtrTy(Ctx), ResumesSize,
+                                "exn.obj", UnwindBB);
+
+  // Extract the exception object from the ResumeInst and add it to the PHI node
+  // that feeds the _Unwind_Resume call.
+  for (SmallVectorImpl<ResumeInst*>::iterator
+         I = Resumes.begin(), E = Resumes.end(); I != E; ++I) {
+    ResumeInst *RI = *I;
+    BasicBlock *Parent = RI->getParent();
+    BranchInst::Create(UnwindBB, Parent);
+
+    Value *ExnObj = GetExceptionObject(RI);
+    PN->addIncoming(ExnObj, Parent);
+
+    ++NumResumesLowered;
+  }
+
+  // Call the function.
+  CallInst *CI = CallInst::Create(RewindFunction, PN, "", UnwindBB);
+  CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));
+
+  // We never expect _Unwind_Resume to return.
+  new UnreachableInst(Ctx, UnwindBB);
+  return true;
+}
+
+bool DwarfEHPrepare::runOnFunction(Function &Fn) {
+  bool Changed = InsertUnwindResumeCalls(Fn);
+  return Changed;
+}