Emit exception handling info for functions which are

not marked nounwind, or for all functions when -enable-eh
is set, provided the target supports Dwarf EH.

llvm-gcc generates nounwind in the right places; other FEs
will need to do so also.  Given such a FE, -enable-eh should
no longer be needed.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@49006 91177308-0d34-0410-b5e6-96231b3b80d8

8 files changed, 49 insertions, 25 deletions

diff --git a/lib/CodeGen/DwarfWriter.cpp b/lib/CodeGen/DwarfWriter.cpp
index e72ff07..3296e11 100644
--- a/lib/CodeGen/DwarfWriter.cpp
+++ b/lib/CodeGen/DwarfWriter.cpp
@@ -2778,9 +2778,13 @@ private:
 
   std::vector<FunctionEHFrameInfo> EHFrames;
     
-  /// shouldEmit - Flag to indicate if debug information should be emitted.
-  ///
+  /// shouldEmit - Per-function flag to indicate if EH information should
+  /// be emitted.
   bool shouldEmit;
+
+  /// shouldEmitModule - Per-module flag to indicate if EH information should
+  /// be emitted.
+  bool shouldEmitModule;
   
   /// EmitCommonEHFrame - Emit the common eh unwind frame.
   ///
@@ -3368,6 +3372,7 @@ public:
   DwarfException(std::ostream &OS, AsmPrinter *A, const TargetAsmInfo *T)
   : Dwarf(OS, A, T, "eh")
   , shouldEmit(false)
+  , shouldEmitModule(false)
   {}
   
   virtual ~DwarfException() {}
@@ -3387,7 +3392,7 @@ public:
   /// EndModule - Emit all exception information that should come after the
   /// content.
   void EndModule() {
-    if (!shouldEmit) return;
+    if (!shouldEmitModule) return;
 
     const std::vector<Function *> Personalities = MMI->getPersonalities();
     for (unsigned i =0; i < Personalities.size(); ++i)
@@ -3403,13 +3408,14 @@ public:
   void BeginFunction(MachineFunction *MF) {
     this->MF = MF;
     
-    if (MMI &&
-        ExceptionHandling &&
+    shouldEmit = false;
+    if ((ExceptionHandling || !MF->getFunction()->doesNotThrow()) &&
         TAI->doesSupportExceptionHandling()) {
       shouldEmit = true;
       // Assumes in correct section after the entry point.
       EmitLabel("eh_func_begin", ++SubprogramCount);
     }
+    shouldEmitModule |= shouldEmit;
   }
 
   /// EndFunction - Gather and emit post-function exception information.
diff --git a/lib/CodeGen/LLVMTargetMachine.cpp b/lib/CodeGen/LLVMTargetMachine.cpp
index bae7140..67c0e47 100644
--- a/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/lib/CodeGen/LLVMTargetMachine.cpp
@@ -66,8 +66,7 @@ LLVMTargetMachine::addPassesToEmitFile(PassManagerBase &PM,
   
   PM.add(createGCLoweringPass());
 
-  if (!ExceptionHandling)
-    PM.add(createLowerInvokePass(getTargetLowering()));
+  PM.add(createLowerInvokePass(getTargetLowering()));
 
   // Make sure that no unreachable blocks are instruction selected.
   PM.add(createUnreachableBlockEliminationPass());
@@ -192,8 +191,7 @@ bool LLVMTargetMachine::addPassesToEmitMachineCode(PassManagerBase &PM,
   
   PM.add(createGCLoweringPass());
   
-  if (!ExceptionHandling)
-    PM.add(createLowerInvokePass(getTargetLowering()));
+  PM.add(createLowerInvokePass(getTargetLowering()));
   
   // Make sure that no unreachable blocks are instruction selected.
   PM.add(createUnreachableBlockEliminationPass());
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 80b5c04..ae2b418 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -169,6 +169,7 @@ namespace llvm {
     Function &Fn;
     MachineFunction &MF;
     MachineRegisterInfo &RegInfo;
+    bool needsExceptionHandling;
 
     FunctionLoweringInfo(TargetLowering &TLI, Function &Fn,MachineFunction &MF);
 
@@ -304,6 +305,10 @@ FunctionLoweringInfo::FunctionLoweringInfo(TargetLowering &tli,
         BuildMI(MBB, TII->get(TargetInstrInfo::PHI), PHIReg+i);
     }
   }
+
+  // Figure out whether we need to generate EH info.  Currently we do this for
+  // all functions not marked no-unwind, or if requested via -enable-eh.
+  needsExceptionHandling = ExceptionHandling || !Fn.doesNotThrow();
 }
 
 /// CreateRegForValue - Allocate the appropriate number of virtual registers of
@@ -2827,7 +2832,7 @@ SelectionDAGLowering::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) {
   }
     
   case Intrinsic::eh_exception: {
-    if (ExceptionHandling) {
+    if (FuncInfo.needsExceptionHandling) {
       if (!CurMBB->isLandingPad()) {
         // FIXME: Mark exception register as live in.  Hack for PR1508.
         unsigned Reg = TLI.getExceptionAddressRegister();
@@ -2852,7 +2857,7 @@ SelectionDAGLowering::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) {
     MVT::ValueType VT = (Intrinsic == Intrinsic::eh_selector_i32 ?
                          MVT::i32 : MVT::i64);
     
-    if (ExceptionHandling && MMI) {
+    if (FuncInfo.needsExceptionHandling && MMI) {
       if (CurMBB->isLandingPad())
         addCatchInfo(I, MMI, CurMBB);
       else {
@@ -2902,7 +2907,7 @@ SelectionDAGLowering::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) {
   case Intrinsic::eh_return: {
     MachineModuleInfo *MMI = DAG.getMachineModuleInfo();
 
-    if (MMI && ExceptionHandling) {
+    if (MMI && FuncInfo.needsExceptionHandling) {
       MMI->setCallsEHReturn(true);
       DAG.setRoot(DAG.getNode(ISD::EH_RETURN,
                               MVT::Other,
@@ -2925,7 +2930,7 @@ SelectionDAGLowering::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) {
    }
 
    case Intrinsic::eh_dwarf_cfa: {
-     if (ExceptionHandling) {
+     if (FuncInfo.needsExceptionHandling) {
        MVT::ValueType VT = getValue(I.getOperand(1)).getValueType();
        SDOperand CfaArg;
        if (MVT::getSizeInBits(VT) > MVT::getSizeInBits(TLI.getPointerTy()))
@@ -3176,7 +3181,7 @@ void SelectionDAGLowering::LowerCallTo(CallSite CS, SDOperand Callee,
     Args.push_back(Entry);
   }
 
-  if (LandingPad && ExceptionHandling && MMI) {
+  if (LandingPad && FuncInfo.needsExceptionHandling && MMI) {
     // Insert a label before the invoke call to mark the try range.  This can be
     // used to detect deletion of the invoke via the MachineModuleInfo.
     BeginLabel = MMI->NextLabelID();
@@ -3195,7 +3200,7 @@ void SelectionDAGLowering::LowerCallTo(CallSite CS, SDOperand Callee,
     setValue(CS.getInstruction(), Result.first);
   DAG.setRoot(Result.second);
 
-  if (LandingPad && ExceptionHandling && MMI) {
+  if (LandingPad && FuncInfo.needsExceptionHandling && MMI) {
     // Insert a label at the end of the invoke call to mark the try range.  This
     // can be used to detect deletion of the invoke via the MachineModuleInfo.
     EndLabel = MMI->NextLabelID();
@@ -4614,7 +4619,7 @@ bool SelectionDAGISel::runOnFunction(Function &Fn) {
 
   FunctionLoweringInfo FuncInfo(TLI, Fn, MF);
 
-  if (ExceptionHandling)
+  if (FuncInfo.needsExceptionHandling)
     for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
       if (InvokeInst *Invoke = dyn_cast<InvokeInst>(I->getTerminator()))
         // Mark landing pad.
@@ -4757,7 +4762,7 @@ void SelectionDAGISel::BuildSelectionDAG(SelectionDAG &DAG, BasicBlock *LLVMBB,
 
   MachineModuleInfo *MMI = DAG.getMachineModuleInfo();
 
-  if (ExceptionHandling && MMI && BB->isLandingPad()) {
+  if (FuncInfo.needsExceptionHandling && MMI && BB->isLandingPad()) {
     // Add a label to mark the beginning of the landing pad.  Deletion of the
     // landing pad can thus be detected via the MachineModuleInfo.
     unsigned LabelID = MMI->addLandingPad(BB);
diff --git a/lib/Target/PowerPC/PPCAsmPrinter.cpp b/lib/Target/PowerPC/PPCAsmPrinter.cpp
index 2537d67..4cc9d2a 100644
--- a/lib/Target/PowerPC/PPCAsmPrinter.cpp
+++ b/lib/Target/PowerPC/PPCAsmPrinter.cpp
@@ -1086,8 +1086,9 @@ bool DarwinAsmPrinter::doFinalization(Module &M) {
 
   O << "\n";
 
-  if (ExceptionHandling && TAI->doesSupportExceptionHandling() && MMI) {
+  if (TAI->doesSupportExceptionHandling() && MMI) {
     // Add the (possibly multiple) personalities to the set of global values.
+    // Only referenced functions get into the Personalities list.
     const std::vector<Function *>& Personalities = MMI->getPersonalities();
 
     for (std::vector<Function *>::const_iterator I = Personalities.begin(),
diff --git a/lib/Target/PowerPC/PPCRegisterInfo.cpp b/lib/Target/PowerPC/PPCRegisterInfo.cpp
index 0e6bc69..cc3b583 100644
--- a/lib/Target/PowerPC/PPCRegisterInfo.cpp
+++ b/lib/Target/PowerPC/PPCRegisterInfo.cpp
@@ -20,6 +20,7 @@
 #include "PPCFrameInfo.h"
 #include "PPCSubtarget.h"
 #include "llvm/Constants.h"
+#include "llvm/Function.h"
 #include "llvm/Type.h"
 #include "llvm/CodeGen/ValueTypes.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
@@ -946,6 +947,8 @@ PPCRegisterInfo::emitPrologue(MachineFunction &MF) const {
   MachineBasicBlock::iterator MBBI = MBB.begin();
   MachineFrameInfo *MFI = MF.getFrameInfo();
   MachineModuleInfo *MMI = MFI->getMachineModuleInfo();
+  bool needsFrameInfo = (MMI && MMI->hasDebugInfo()) ||
+       ExceptionHandling || !MF.getFunction()->doesNotThrow();
   
   // Prepare for frame info.
   unsigned FrameLabelId = 0;
@@ -1019,7 +1022,7 @@ PPCRegisterInfo::emitPrologue(MachineFunction &MF) const {
   unsigned TargetAlign = MF.getTarget().getFrameInfo()->getStackAlignment();
   unsigned MaxAlign = MFI->getMaxAlignment();
 
-  if (MMI && MMI->needsFrameInfo()) {
+  if (needsFrameInfo) {
     // Mark effective beginning of when frame pointer becomes valid.
     FrameLabelId = MMI->NextLabelID();
     BuildMI(MBB, MBBI, TII.get(PPC::LABEL)).addImm(FrameLabelId).addImm(0);
@@ -1095,7 +1098,7 @@ PPCRegisterInfo::emitPrologue(MachineFunction &MF) const {
     }
   }
   
-  if (MMI && MMI->needsFrameInfo()) {
+  if (needsFrameInfo) {
     std::vector<MachineMove> &Moves = MMI->getFrameMoves();
     
     if (NegFrameSize) {
diff --git a/lib/Target/X86/X86AsmPrinter.cpp b/lib/Target/X86/X86AsmPrinter.cpp
index 98e7d9c..e1bc65f 100644
--- a/lib/Target/X86/X86AsmPrinter.cpp
+++ b/lib/Target/X86/X86AsmPrinter.cpp
@@ -381,9 +381,9 @@ bool X86SharedAsmPrinter::doFinalization(Module &M) {
 
     O << "\n";
 
-    if (ExceptionHandling && TAI->doesSupportExceptionHandling() && MMI &&
-        !Subtarget->is64Bit()) {
+    if (TAI->doesSupportExceptionHandling() && MMI && !Subtarget->is64Bit()) {
       // Add the (possibly multiple) personalities to the set of global values.
+      // Only referenced functions get into the Personalities list.
       const std::vector<Function *>& Personalities = MMI->getPersonalities();
 
       for (std::vector<Function *>::const_iterator I = Personalities.begin(),
diff --git a/lib/Target/X86/X86RegisterInfo.cpp b/lib/Target/X86/X86RegisterInfo.cpp
index 5cd2fbe..95026f2 100644
--- a/lib/Target/X86/X86RegisterInfo.cpp
+++ b/lib/Target/X86/X86RegisterInfo.cpp
@@ -504,6 +504,8 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
   MachineModuleInfo *MMI = MFI->getMachineModuleInfo();
   X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
   MachineBasicBlock::iterator MBBI = MBB.begin();
+  bool needsFrameInfo = (MMI && MMI->hasDebugInfo()) ||
+      ExceptionHandling || !Fn->doesNotThrow();
   
   // Prepare for frame info.
   unsigned FrameLabelId = 0;
@@ -536,7 +538,7 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
       .addReg(FramePtr);
     NumBytes -= SlotSize;
 
-    if (MMI && MMI->needsFrameInfo()) {
+    if (needsFrameInfo) {
       // Mark effective beginning of when frame pointer becomes valid.
       FrameLabelId = MMI->NextLabelID();
       BuildMI(MBB, MBBI, TII.get(X86::LABEL)).addImm(FrameLabelId).addImm(0);
@@ -548,7 +550,7 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
   }
   
   unsigned ReadyLabelId = 0;
-  if (MMI && MMI->needsFrameInfo()) {
+  if (needsFrameInfo) {
     // Mark effective beginning of when frame pointer is ready.
     ReadyLabelId = MMI->NextLabelID();
     BuildMI(MBB, MBBI, TII.get(X86::LABEL)).addImm(ReadyLabelId).addImm(0);
@@ -607,7 +609,7 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
     }
   }
 
-  if (MMI && MMI->needsFrameInfo()) {
+  if (needsFrameInfo) {
     std::vector<MachineMove> &Moves = MMI->getFrameMoves();
     const TargetData *TD = MF.getTarget().getTargetData();
 
diff --git a/lib/Transforms/Utils/LowerInvoke.cpp b/lib/Transforms/Utils/LowerInvoke.cpp
index 7f0ef85..f546c33 100644
--- a/lib/Transforms/Utils/LowerInvoke.cpp
+++ b/lib/Transforms/Utils/LowerInvoke.cpp
@@ -47,6 +47,9 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Target/TargetLowering.h"
+#include "llvm/Target/TargetOptions.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetAsmInfo.h"
 #include <csetjmp>
 #include <set>
 using namespace llvm;
@@ -592,6 +595,12 @@ bool LowerInvoke::insertExpensiveEHSupport(Function &F) {
 }
 
 bool LowerInvoke::runOnFunction(Function &F) {
+  // If we will be generating exception info, don't do anything here.
+  if ((ExceptionHandling || !F.doesNotThrow()) &&
+      TLI &&
+      TLI->getTargetMachine().getTargetAsmInfo()->
+                              doesSupportExceptionHandling())
+    return false;
   if (ExpensiveEHSupport)
     return insertExpensiveEHSupport(F);
   else