X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FDwarfEHPrepare.cpp;h=d1261a3565b93417b536e59898b40e1befcaa944;hb=23eaf26fa3510526b11230c76ea39221277dd2ea;hp=a2e6068ff87d41e1b58b89092a7e1922481f4218;hpb=82f149d794dcb705a05e9e260402cbf3f36f1957;p=oota-llvm.git

diff --git a/lib/CodeGen/DwarfEHPrepare.cpp b/lib/CodeGen/DwarfEHPrepare.cpp
index a2e6068ff87..d1261a3565b 100644
--- a/lib/CodeGen/DwarfEHPrepare.cpp
+++ b/lib/CodeGen/DwarfEHPrepare.cpp
@@ -8,20 +8,20 @@
 //===----------------------------------------------------------------------===//
 //
 // This pass mulches exception handling code into a form adapted to code
-// generation.  Required if using dwarf exception handling.
+// generation. Required if using dwarf exception handling.
 //
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "dwarfehprepare"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/Dominators.h"
-#include "llvm/CodeGen/Passes.h"
 #include "llvm/Function.h"
 #include "llvm/Instructions.h"
 #include "llvm/IntrinsicInst.h"
 #include "llvm/Module.h"
 #include "llvm/Pass.h"
-#include "llvm/Support/Compiler.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/MC/MCAsmInfo.h"
 #include "llvm/Target/TargetLowering.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
@@ -33,13 +33,22 @@ STATISTIC(NumExceptionValuesMoved, "Number of eh.exception calls moved");
 STATISTIC(NumStackTempsIntroduced, "Number of stack temporaries introduced");
 
 namespace {
-  class VISIBILITY_HIDDEN DwarfEHPrepare : public FunctionPass {
+  class DwarfEHPrepare : public FunctionPass {
     const TargetLowering *TLI;
     bool CompileFast;
 
     // The eh.exception intrinsic.
     Function *ExceptionValueIntrinsic;
 
+    // The eh.selector intrinsic.
+    Function *SelectorIntrinsic;
+
+    // _Unwind_Resume_or_Rethrow call.
+    Constant *URoR;
+
+    // The EH language-specific catch-all type.
+    GlobalVariable *EHCatchAllValue;
+
     // _Unwind_Resume or the target equivalent.
     Constant *RewindFunction;
 
@@ -67,18 +76,88 @@ namespace {
     Instruction *CreateValueLoad(BasicBlock *BB);
 
     /// CreateReadOfExceptionValue - Return the result of the eh.exception
-    /// intrinsic by calling the intrinsic if in a landing pad, or loading
-    /// it from the exception value variable otherwise.
+    /// intrinsic by calling the intrinsic if in a landing pad, or loading it
+    /// from the exception value variable otherwise.
     Instruction *CreateReadOfExceptionValue(BasicBlock *BB) {
       return LandingPads.count(BB) ?
         CreateExceptionValueCall(BB) : CreateValueLoad(BB);
     }
 
+    /// CleanupSelectors - Any remaining eh.selector intrinsic calls which still
+    /// use the ".llvm.eh.catch.all.value" call need to convert to using its
+    /// initializer instead.
+    bool CleanupSelectors();
+
+    /// FindAllCleanupSelectors - Find all eh.selector calls that are clean-ups.
+    void FindAllCleanupSelectors(SmallPtrSet<IntrinsicInst*, 32> &Sels);
+
+    /// FindAllURoRInvokes - Find all URoR invokes in the function.
+    void FindAllURoRInvokes(SmallPtrSet<InvokeInst*, 32> &URoRInvokes);
+
+    /// HandleURoRInvokes - Handle invokes of "_Unwind_Resume_or_Rethrow"
+    /// calls. The "unwind" part of these invokes jump to a landing pad within
+    /// the current function. This is a candidate to merge the selector
+    /// associated with the URoR invoke with the one from the URoR's landing
+    /// pad.
+    bool HandleURoRInvokes();
+
+    /// FindSelectorAndURoR - Find the eh.selector call and URoR call associated
+    /// with the eh.exception call. This recursively looks past instructions
+    /// which don't change the EH pointer value, like casts or PHI nodes.
+    bool FindSelectorAndURoR(Instruction *Inst, bool &URoRInvoke,
+                             SmallPtrSet<IntrinsicInst*, 8> &SelCalls);
+      
+    /// DoMem2RegPromotion - Take an alloca call and promote it from memory to a
+    /// register.
+    bool DoMem2RegPromotion(Value *V) {
+      AllocaInst *AI = dyn_cast<AllocaInst>(V);
+      if (!AI || !isAllocaPromotable(AI)) return false;
+
+      // Turn the alloca into a register.
+      std::vector<AllocaInst*> Allocas(1, AI);
+      PromoteMemToReg(Allocas, *DT, *DF);
+      return true;
+    }
+
+    /// PromoteStoreInst - Perform Mem2Reg on a StoreInst.
+    bool PromoteStoreInst(StoreInst *SI) {
+      if (!SI || !DT || !DF) return false;
+      if (DoMem2RegPromotion(SI->getOperand(1)))
+        return true;
+      return false;
+    }
+
+    /// PromoteEHPtrStore - Promote the storing of an EH pointer into a
+    /// register. This should get rid of the store and subsequent loads.
+    bool PromoteEHPtrStore(IntrinsicInst *II) {
+      if (!DT || !DF) return false;
+
+      bool Changed = false;
+      StoreInst *SI;
+
+      while (1) {
+        SI = 0;
+        for (Value::use_iterator
+               I = II->use_begin(), E = II->use_end(); I != E; ++I) {
+          SI = dyn_cast<StoreInst>(I);
+          if (SI) break;
+        }
+
+        if (!PromoteStoreInst(SI))
+          break;
+
+        Changed = true;
+      }
+
+      return false;
+    }
+
   public:
     static char ID; // Pass identification, replacement for typeid.
     DwarfEHPrepare(const TargetLowering *tli, bool fast) :
       FunctionPass(&ID), TLI(tli), CompileFast(fast),
-      ExceptionValueIntrinsic(0), RewindFunction(0) {}
+      ExceptionValueIntrinsic(0), SelectorIntrinsic(0),
+      URoR(0), EHCatchAllValue(0), RewindFunction(0) {}
 
     virtual bool runOnFunction(Function &Fn);
 
@@ -105,14 +184,246 @@ FunctionPass *llvm::createDwarfEHPass(const TargetLowering *tli, bool fast) {
   return new DwarfEHPrepare(tli, fast);
 }
 
+/// FindAllCleanupSelectors - Find all eh.selector calls that are clean-ups.
+void DwarfEHPrepare::
+FindAllCleanupSelectors(SmallPtrSet<IntrinsicInst*, 32> &Sels) {
+  for (Value::use_iterator
+         I = SelectorIntrinsic->use_begin(),
+         E = SelectorIntrinsic->use_end(); I != E; ++I) {
+    IntrinsicInst *SI = cast<IntrinsicInst>(I);
+    if (!SI || SI->getParent()->getParent() != F) continue;
+
+    unsigned NumOps = SI->getNumOperands();
+    if (NumOps > 4) continue;
+    bool IsCleanUp = (NumOps == 3);
+
+    if (!IsCleanUp)
+      if (ConstantInt *CI = dyn_cast<ConstantInt>(SI->getOperand(3)))
+        IsCleanUp = (CI->getZExtValue() == 0);
+
+    if (IsCleanUp)
+      Sels.insert(SI);
+  }
+}
+
+/// FindAllURoRInvokes - Find all URoR invokes in the function.
+void DwarfEHPrepare::
+FindAllURoRInvokes(SmallPtrSet<InvokeInst*, 32> &URoRInvokes) {
+  for (Value::use_iterator
+         I = URoR->use_begin(),
+         E = URoR->use_end(); I != E; ++I) {
+    if (InvokeInst *II = dyn_cast<InvokeInst>(I))
+      URoRInvokes.insert(II);
+  }
+}
+
+/// CleanupSelectors - Any remaining eh.selector intrinsic calls which still use
+/// the ".llvm.eh.catch.all.value" call need to convert to using its
+/// initializer instead.
+bool DwarfEHPrepare::CleanupSelectors() {
+  if (!EHCatchAllValue) return false;
+
+  if (!SelectorIntrinsic) {
+    SelectorIntrinsic =
+      Intrinsic::getDeclaration(F->getParent(), Intrinsic::eh_selector);
+    if (!SelectorIntrinsic) return false;
+  }
+
+  bool Changed = false;
+  for (Value::use_iterator
+         I = SelectorIntrinsic->use_begin(),
+         E = SelectorIntrinsic->use_end(); I != E; ++I) {
+    IntrinsicInst *Sel = dyn_cast<IntrinsicInst>(I);
+    if (!Sel || Sel->getParent()->getParent() != F) continue;
+
+    // Index of the ".llvm.eh.catch.all.value" variable.
+    unsigned OpIdx = Sel->getNumOperands() - 1;
+    GlobalVariable *GV = dyn_cast<GlobalVariable>(Sel->getOperand(OpIdx));
+    if (GV != EHCatchAllValue) continue;
+    Sel->setOperand(OpIdx, EHCatchAllValue->getInitializer());
+    Changed = true;
+  }
+
+  return Changed;
+}
+
+/// FindSelectorAndURoR - Find the eh.selector call associated with the
+/// eh.exception call. And indicate if there is a URoR "invoke" associated with
+/// the eh.exception call. This recursively looks past instructions which don't
+/// change the EH pointer value, like casts or PHI nodes.
+bool
+DwarfEHPrepare::FindSelectorAndURoR(Instruction *Inst, bool &URoRInvoke,
+                                    SmallPtrSet<IntrinsicInst*, 8> &SelCalls) {
+  SmallPtrSet<PHINode*, 32> SeenPHIs;
+  bool Changed = false;
+
+ restart:
+  for (Value::use_iterator
+         I = Inst->use_begin(), E = Inst->use_end(); I != E; ++I) {
+    Instruction *II = dyn_cast<Instruction>(I);
+    if (!II || II->getParent()->getParent() != F) continue;
+    
+    if (IntrinsicInst *Sel = dyn_cast<IntrinsicInst>(II)) {
+      if (Sel->getIntrinsicID() == Intrinsic::eh_selector)
+        SelCalls.insert(Sel);
+    } else if (InvokeInst *Invoke = dyn_cast<InvokeInst>(II)) {
+      if (Invoke->getCalledFunction() == URoR)
+        URoRInvoke = true;
+    } else if (CastInst *CI = dyn_cast<CastInst>(II)) {
+      Changed |= FindSelectorAndURoR(CI, URoRInvoke, SelCalls);
+    } else if (StoreInst *SI = dyn_cast<StoreInst>(II)) {
+      if (!PromoteStoreInst(SI)) continue;
+      Changed = true;
+      SeenPHIs.clear();
+      goto restart;             // Uses may have changed, restart loop.
+    } else if (PHINode *PN = dyn_cast<PHINode>(II)) {
+      if (SeenPHIs.insert(PN))
+        // Don't process a PHI node more than once.
+        Changed |= FindSelectorAndURoR(PN, URoRInvoke, SelCalls);
+    }
+  }
+
+  return Changed;
+}
+
+/// HandleURoRInvokes - Handle invokes of "_Unwind_Resume_or_Rethrow" calls. The
+/// "unwind" part of these invokes jump to a landing pad within the current
+/// function. This is a candidate to merge the selector associated with the URoR
+/// invoke with the one from the URoR's landing pad.
+bool DwarfEHPrepare::HandleURoRInvokes() {
+  if (!DT) return CleanupSelectors(); // We require DominatorTree information.
+
+  if (!EHCatchAllValue) {
+    EHCatchAllValue =
+      F->getParent()->getNamedGlobal(".llvm.eh.catch.all.value");
+    if (!EHCatchAllValue) return false;
+  }
+
+  if (!SelectorIntrinsic) {
+    SelectorIntrinsic =
+      Intrinsic::getDeclaration(F->getParent(), Intrinsic::eh_selector);
+    if (!SelectorIntrinsic) return false;
+  }
+
+  if (!URoR) {
+    URoR = F->getParent()->getFunction("_Unwind_Resume_or_Rethrow");
+    if (!URoR) return CleanupSelectors();
+  }
+
+  SmallPtrSet<IntrinsicInst*, 32> Sels;
+  SmallPtrSet<InvokeInst*, 32> URoRInvokes;
+  FindAllCleanupSelectors(Sels);
+  FindAllURoRInvokes(URoRInvokes);
+
+  SmallPtrSet<IntrinsicInst*, 32> SelsToConvert;
+
+  for (SmallPtrSet<IntrinsicInst*, 32>::iterator
+         SI = Sels.begin(), SE = Sels.end(); SI != SE; ++SI) {
+    const BasicBlock *SelBB = (*SI)->getParent();
+    for (SmallPtrSet<InvokeInst*, 32>::iterator
+           UI = URoRInvokes.begin(), UE = URoRInvokes.end(); UI != UE; ++UI) {
+      const BasicBlock *URoRBB = (*UI)->getParent();
+      if (SelBB == URoRBB || DT->dominates(SelBB, URoRBB)) {
+        SelsToConvert.insert(*SI);
+        break;
+      }
+    }
+  }
+
+  bool Changed = false;
+
+  if (Sels.size() != SelsToConvert.size()) {
+    // If we haven't been able to convert all of the clean-up selectors, then
+    // loop through the slow way to see if they still need to be converted.
+    if (!ExceptionValueIntrinsic) {
+      ExceptionValueIntrinsic =
+        Intrinsic::getDeclaration(F->getParent(), Intrinsic::eh_exception);
+      if (!ExceptionValueIntrinsic) return CleanupSelectors();
+    }
+
+    for (Value::use_iterator
+           I = ExceptionValueIntrinsic->use_begin(),
+           E = ExceptionValueIntrinsic->use_end(); I != E; ++I) {
+      IntrinsicInst *EHPtr = dyn_cast<IntrinsicInst>(I);
+      if (!EHPtr || EHPtr->getParent()->getParent() != F) continue;
+
+      Changed |= PromoteEHPtrStore(EHPtr);
+
+      bool URoRInvoke = false;
+      SmallPtrSet<IntrinsicInst*, 8> SelCalls;
+      Changed |= FindSelectorAndURoR(EHPtr, URoRInvoke, SelCalls);
+
+      if (URoRInvoke) {
+        // This EH pointer is being used by an invoke of an URoR instruction and
+        // an eh.selector intrinsic call. If the eh.selector is a 'clean-up', we
+        // need to convert it to a 'catch-all'.
+        for (SmallPtrSet<IntrinsicInst*, 8>::iterator
+               SI = SelCalls.begin(), SE = SelCalls.end(); SI != SE; ++SI) {
+          IntrinsicInst *II = *SI;
+          unsigned NumOps = II->getNumOperands();
+
+          if (NumOps <= 4) {
+            bool IsCleanUp = (NumOps == 3);
+
+            if (!IsCleanUp)
+              if (ConstantInt *CI = dyn_cast<ConstantInt>(II->getOperand(3)))
+                IsCleanUp = (CI->getZExtValue() == 0);
+
+            if (IsCleanUp)
+              SelsToConvert.insert(II);
+          }
+        }
+      }
+    }
+  }
+
+  if (!SelsToConvert.empty()) {
+    // Convert all clean-up eh.selectors, which are associated with "invokes" of
+    // URoR calls, into catch-all eh.selectors.
+    Changed = true;
+
+    for (SmallPtrSet<IntrinsicInst*, 8>::iterator
+           SI = SelsToConvert.begin(), SE = SelsToConvert.end();
+         SI != SE; ++SI) {
+      IntrinsicInst *II = *SI;
+      SmallVector<Value*, 8> Args;
+
+      // Use the exception object pointer and the personality function
+      // from the original selector.
+      Args.push_back(II->getOperand(1)); // Exception object pointer.
+      Args.push_back(II->getOperand(2)); // Personality function.
+      Args.push_back(EHCatchAllValue->getInitializer()); // Catch-all indicator.
+
+      CallInst *NewSelector =
+        CallInst::Create(SelectorIntrinsic, Args.begin(), Args.end(),
+                         "eh.sel.catch.all", II);
+
+      NewSelector->setTailCall(II->isTailCall());
+      NewSelector->setAttributes(II->getAttributes());
+      NewSelector->setCallingConv(II->getCallingConv());
+
+      II->replaceAllUsesWith(NewSelector);
+      II->eraseFromParent();
+    }
+  }
+
+  Changed |= CleanupSelectors();
+  return Changed;
+}
+
 /// NormalizeLandingPads - Normalize and discover landing pads, noting them
 /// in the LandingPads set.  A landing pad is normal if the only CFG edges
-/// that end at it are unwind edges from invoke instructions.
+/// that end at it are unwind edges from invoke instructions. If we inlined
+/// through an invoke we could have a normal branch from the previous
+/// unwind block through to the landing pad for the original invoke.
 /// Abnormal landing pads are fixed up by redirecting all unwind edges to
 /// a new basic block which falls through to the original.
 bool DwarfEHPrepare::NormalizeLandingPads() {
   bool Changed = false;
 
+  const MCAsmInfo *MAI = TLI->getTargetMachine().getMCAsmInfo();
+  bool usingSjLjEH = MAI->getExceptionHandlingType() == ExceptionHandling::SjLj;
+
   for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
     TerminatorInst *TI = I->getTerminator();
     if (!isa<InvokeInst>(TI))
@@ -124,14 +435,24 @@ bool DwarfEHPrepare::NormalizeLandingPads() {
 
     // Check that only invoke unwind edges end at the landing pad.
     bool OnlyUnwoundTo = true;
+    bool SwitchOK = usingSjLjEH;
     for (pred_iterator PI = pred_begin(LPad), PE = pred_end(LPad);
          PI != PE; ++PI) {
       TerminatorInst *PT = (*PI)->getTerminator();
+      // The SjLj dispatch block uses a switch instruction. This is effectively
+      // an unwind edge, so we can disregard it here. There will only ever
+      // be one dispatch, however, so if there are multiple switches, one
+      // of them truly is a normal edge, not an unwind edge.
+      if (SwitchOK && isa<SwitchInst>(PT)) {
+        SwitchOK = false;
+        continue;
+      }
       if (!isa<InvokeInst>(PT) || LPad == PT->getSuccessor(0)) {
         OnlyUnwoundTo = false;
         break;
       }
     }
+
     if (OnlyUnwoundTo) {
       // Only unwind edges lead to the landing pad.  Remember the landing pad.
       LandingPads.insert(LPad);
@@ -219,29 +540,40 @@ bool DwarfEHPrepare::NormalizeLandingPads() {
 /// at runtime if there is no such exception: using unwind to throw a new
 /// exception is currently not supported.
 bool DwarfEHPrepare::LowerUnwinds() {
-  bool Changed = false;
+  SmallVector<TerminatorInst*, 16> UnwindInsts;
 
   for (Function::iterator I = F->begin(), E = F->end(); I != E; ++I) {
     TerminatorInst *TI = I->getTerminator();
-    if (!isa<UnwindInst>(TI))
-      continue;
+    if (isa<UnwindInst>(TI))
+      UnwindInsts.push_back(TI);
+  }
+
+  if (UnwindInsts.empty()) return false;
+
+  // Find the rewind function if we didn't already.
+  if (!RewindFunction) {
+    LLVMContext &Ctx = UnwindInsts[0]->getContext();
+    std::vector<const Type*>
+      Params(1, Type::getInt8PtrTy(Ctx));
+    FunctionType *FTy = FunctionType::get(Type::getVoidTy(Ctx),
+                                          Params, false);
+    const char *RewindName = TLI->getLibcallName(RTLIB::UNWIND_RESUME);
+    RewindFunction = F->getParent()->getOrInsertFunction(RewindName, FTy);
+  }
+
+  bool Changed = false;
+
+  for (SmallVectorImpl<TerminatorInst*>::iterator
+         I = UnwindInsts.begin(), E = UnwindInsts.end(); I != E; ++I) {
+    TerminatorInst *TI = *I;
 
     // Replace the unwind instruction with a call to _Unwind_Resume (or the
     // appropriate target equivalent) followed by an UnreachableInst.
 
-    // Find the rewind function if we didn't already.
-    if (!RewindFunction) {
-      std::vector<const Type*> Params(1,
-                     PointerType::getUnqual(Type::getInt8Ty(TI->getContext())));
-      FunctionType *FTy = FunctionType::get(Type::getVoidTy(TI->getContext()),
-                                            Params, false);
-      const char *RewindName = TLI->getLibcallName(RTLIB::UNWIND_RESUME);
-      RewindFunction = F->getParent()->getOrInsertFunction(RewindName, FTy);
-    }
-
     // Create the call...
     CallInst *CI = CallInst::Create(RewindFunction,
-				    CreateReadOfExceptionValue(I), "", TI);
+                                    CreateReadOfExceptionValue(TI->getParent()),
+                                    "", TI);
     CI->setCallingConv(TLI->getLibcallCallingConv(RTLIB::UNWIND_RESUME));
     // ...followed by an UnreachableInst.
     new UnreachableInst(TI->getContext(), TI);
@@ -319,7 +651,7 @@ bool DwarfEHPrepare::PromoteStackTemporaries() {
   if (ExceptionValueVar && DT && DF && isAllocaPromotable(ExceptionValueVar)) {
     // Turn the exception temporary into registers and phi nodes if possible.
     std::vector<AllocaInst*> Allocas(1, ExceptionValueVar);
-    PromoteMemToReg(Allocas, *DT, *DF, ExceptionValueVar->getContext());
+    PromoteMemToReg(Allocas, *DT, *DF);
     return true;
   }
   return false;
@@ -329,7 +661,7 @@ bool DwarfEHPrepare::PromoteStackTemporaries() {
 /// the start of the basic block (unless there already is one, in which case
 /// the existing call is returned).
 Instruction *DwarfEHPrepare::CreateExceptionValueCall(BasicBlock *BB) {
-  Instruction *Start = BB->getFirstNonPHI();
+  Instruction *Start = BB->getFirstNonPHIOrDbg();
   // Is this a call to eh.exception?
   if (IntrinsicInst *CI = dyn_cast<IntrinsicInst>(Start))
     if (CI->getIntrinsicID() == Intrinsic::eh_exception)
@@ -349,7 +681,7 @@ Instruction *DwarfEHPrepare::CreateExceptionValueCall(BasicBlock *BB) {
 /// (creating it if necessary) at the start of the basic block (unless
 /// there already is a load, in which case the existing load is returned).
 Instruction *DwarfEHPrepare::CreateValueLoad(BasicBlock *BB) {
-  Instruction *Start = BB->getFirstNonPHI();
+  Instruction *Start = BB->getFirstNonPHIOrDbg();
   // Is this a load of the exception temporary?
   if (ExceptionValueVar)
     if (LoadInst* LI = dyn_cast<LoadInst>(Start))
@@ -396,6 +728,8 @@ bool DwarfEHPrepare::runOnFunction(Function &Fn) {
   if (!CompileFast)
     Changed |= PromoteStackTemporaries();
 
+  Changed |= HandleURoRInvokes();
+
   LandingPads.clear();
 
   return Changed;