Recommitting EH patch; this should answer most of the

review feedback.
-enable-eh is still accepted but doesn't do anything.
EH intrinsics use Dwarf EH if the target supports that,
and are handled by LowerInvoke otherwise.
The separation of the EH table and frame move data is,
I think, logically figured out, but either one still
causes full EH info to be generated (not sure how to
split the metadata correctly).
MachineModuleInfo::needsFrameInfo is no longer used and
is removed.

llvm-svn: 49064

4 files changed, 98 insertions, 90 deletions

diff --git a/llvm/lib/CodeGen/DwarfWriter.cpp b/llvm/lib/CodeGen/DwarfWriter.cpp
index e72ff07a9d7..0fa956e0972 100644
--- a/llvm/lib/CodeGen/DwarfWriter.cpp
+++ b/llvm/lib/CodeGen/DwarfWriter.cpp
@@ -2777,10 +2777,22 @@ private:
   };
 
   std::vector<FunctionEHFrameInfo> EHFrames;
-    
-  /// shouldEmit - Flag to indicate if debug information should be emitted.
-  ///
-  bool shouldEmit;
+
+  /// shouldEmitTable - Per-function flag to indicate if EH tables should
+  /// be emitted.
+  bool shouldEmitTable;
+
+  /// shouldEmitMoves - Per-function flag to indicate if frame moves info
+  /// should be emitted.
+  bool shouldEmitMoves;
+
+  /// shouldEmitTableModule - Per-module flag to indicate if EH tables
+  /// should be emitted.
+  bool shouldEmitTableModule;
+
+  /// shouldEmitFrameModule - Per-module flag to indicate if frame moves 
+  /// should be emitted.
+  bool shouldEmitMovesModule;
   
   /// EmitCommonEHFrame - Emit the common eh unwind frame.
   ///
@@ -3045,9 +3057,6 @@ private:
   };
 
   void EmitExceptionTable() {
-    // Map all labels and get rid of any dead landing pads.
-    MMI->TidyLandingPads();
-
     const std::vector<GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
     const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
     const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
@@ -3367,7 +3376,10 @@ public:
   //
   DwarfException(std::ostream &OS, AsmPrinter *A, const TargetAsmInfo *T)
   : Dwarf(OS, A, T, "eh")
-  , shouldEmit(false)
+  , shouldEmitTable(false)
+  , shouldEmitMoves(false)
+  , shouldEmitTableModule(false)
+  , shouldEmitMovesModule(false)
   {}
   
   virtual ~DwarfException() {}
@@ -3387,48 +3399,59 @@ public:
   /// EndModule - Emit all exception information that should come after the
   /// content.
   void EndModule() {
-    if (!shouldEmit) return;
-
-    const std::vector<Function *> Personalities = MMI->getPersonalities();
-    for (unsigned i =0; i < Personalities.size(); ++i)
-      EmitCommonEHFrame(Personalities[i], i);
-
-    for (std::vector<FunctionEHFrameInfo>::iterator I = EHFrames.begin(),
-           E = EHFrames.end(); I != E; ++I)
-      EmitEHFrame(*I);
+    if (shouldEmitMovesModule || shouldEmitTableModule) {
+      const std::vector<Function *> Personalities = MMI->getPersonalities();
+      for (unsigned i =0; i < Personalities.size(); ++i)
+        EmitCommonEHFrame(Personalities[i], i);
+
+      for (std::vector<FunctionEHFrameInfo>::iterator I = EHFrames.begin(),
+             E = EHFrames.end(); I != E; ++I)
+        EmitEHFrame(*I);
+    }
   }
 
   /// BeginFunction - Gather pre-function exception information.  Assumes being 
   /// emitted immediately after the function entry point.
   void BeginFunction(MachineFunction *MF) {
     this->MF = MF;
-    
-    if (MMI &&
-        ExceptionHandling &&
-        TAI->doesSupportExceptionHandling()) {
-      shouldEmit = true;
-      // Assumes in correct section after the entry point.
-      EmitLabel("eh_func_begin", ++SubprogramCount);
+    shouldEmitTable = shouldEmitMoves = false;
+    if (TAI->doesSupportExceptionHandling()) {
+
+      // Map all labels and get rid of any dead landing pads.
+      MMI->TidyLandingPads();
+      // If any landing pads survive, we need an EH table.
+      if (MMI->getLandingPads().size())
+        shouldEmitTable = true;
+
+      // See if we need frame move info.
+      if (MMI->hasDebugInfo() || !MF->getFunction()->doesNotThrow())
+        shouldEmitMoves = true;
+
+      if (shouldEmitMoves || shouldEmitTable)
+        // Assumes in correct section after the entry point.
+        EmitLabel("eh_func_begin", ++SubprogramCount);
     }
+    shouldEmitTableModule |= shouldEmitTable;
+    shouldEmitMovesModule |= shouldEmitMoves;
   }
 
   /// EndFunction - Gather and emit post-function exception information.
   ///
   void EndFunction() {
-    if (!shouldEmit) return;
+    if (shouldEmitMoves || shouldEmitTable) {
+      EmitLabel("eh_func_end", SubprogramCount);
+      EmitExceptionTable();
 
-    EmitLabel("eh_func_end", SubprogramCount);
-    EmitExceptionTable();
-
-    // Save EH frame information
-    EHFrames.
-      push_back(FunctionEHFrameInfo(getAsm()->getCurrentFunctionEHName(MF),
+      // Save EH frame information
+      EHFrames.
+        push_back(FunctionEHFrameInfo(getAsm()->getCurrentFunctionEHName(MF),
                                     SubprogramCount,
                                     MMI->getPersonalityIndex(),
                                     MF->getFrameInfo()->hasCalls(),
                                     !MMI->getLandingPads().empty(),
                                     MMI->getFrameMoves(),
                                     MF->getFunction()));
+      }
   }
 };
 
diff --git a/llvm/lib/CodeGen/LLVMTargetMachine.cpp b/llvm/lib/CodeGen/LLVMTargetMachine.cpp
index bae7140bfb1..c65a6b9a795 100644
--- a/llvm/lib/CodeGen/LLVMTargetMachine.cpp
+++ b/llvm/lib/CodeGen/LLVMTargetMachine.cpp
@@ -19,6 +19,7 @@
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/CodeGen/Collector.h"
 #include "llvm/Target/TargetOptions.h"
+#include "llvm/Target/TargetAsmInfo.h"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Support/CommandLine.h"
 using namespace llvm;
@@ -66,7 +67,7 @@ LLVMTargetMachine::addPassesToEmitFile(PassManagerBase &PM,
   
   PM.add(createGCLoweringPass());
 
-  if (!ExceptionHandling)
+  if (!getTargetAsmInfo()->doesSupportExceptionHandling())
     PM.add(createLowerInvokePass(getTargetLowering()));
 
   // Make sure that no unreachable blocks are instruction selected.
@@ -192,7 +193,7 @@ bool LLVMTargetMachine::addPassesToEmitMachineCode(PassManagerBase &PM,
   
   PM.add(createGCLoweringPass());
   
-  if (!ExceptionHandling)
+  if (!getTargetAsmInfo()->doesSupportExceptionHandling())
     PM.add(createLowerInvokePass(getTargetLowering()));
   
   // Make sure that no unreachable blocks are instruction selected.
diff --git a/llvm/lib/CodeGen/MachineModuleInfo.cpp b/llvm/lib/CodeGen/MachineModuleInfo.cpp
index 2446bff293d..0cfcc61b780 100644
--- a/llvm/lib/CodeGen/MachineModuleInfo.cpp
+++ b/llvm/lib/CodeGen/MachineModuleInfo.cpp
@@ -1583,12 +1583,6 @@ void MachineModuleInfo::AnalyzeModule(Module &M) {
   }
 }
 
-/// needsFrameInfo - Returns true if we need to gather callee-saved register
-/// move info for the frame.
-bool MachineModuleInfo::needsFrameInfo() const {
-  return hasDebugInfo() || ExceptionHandling;
-}
-
 /// SetupCompileUnits - Set up the unique vector of compile units.
 ///
 void MachineModuleInfo::SetupCompileUnits(Module &M) {
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 80b5c046a71..f237cafd493 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -2827,22 +2827,18 @@ SelectionDAGLowering::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) {
   }
     
   case Intrinsic::eh_exception: {
-    if (ExceptionHandling) {
-      if (!CurMBB->isLandingPad()) {
-        // FIXME: Mark exception register as live in.  Hack for PR1508.
-        unsigned Reg = TLI.getExceptionAddressRegister();
-        if (Reg) CurMBB->addLiveIn(Reg);
-      }
-      // Insert the EXCEPTIONADDR instruction.
-      SDVTList VTs = DAG.getVTList(TLI.getPointerTy(), MVT::Other);
-      SDOperand Ops[1];
-      Ops[0] = DAG.getRoot();
-      SDOperand Op = DAG.getNode(ISD::EXCEPTIONADDR, VTs, Ops, 1);
-      setValue(&I, Op);
-      DAG.setRoot(Op.getValue(1));
-    } else {
-      setValue(&I, DAG.getConstant(0, TLI.getPointerTy()));
+    if (!CurMBB->isLandingPad()) {
+      // FIXME: Mark exception register as live in.  Hack for PR1508.
+      unsigned Reg = TLI.getExceptionAddressRegister();
+      if (Reg) CurMBB->addLiveIn(Reg);
     }
+    // Insert the EXCEPTIONADDR instruction.
+    SDVTList VTs = DAG.getVTList(TLI.getPointerTy(), MVT::Other);
+    SDOperand Ops[1];
+    Ops[0] = DAG.getRoot();
+    SDOperand Op = DAG.getNode(ISD::EXCEPTIONADDR, VTs, Ops, 1);
+    setValue(&I, Op);
+    DAG.setRoot(Op.getValue(1));
     return 0;
   }
 
@@ -2852,7 +2848,7 @@ SelectionDAGLowering::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) {
     MVT::ValueType VT = (Intrinsic == Intrinsic::eh_selector_i32 ?
                          MVT::i32 : MVT::i64);
     
-    if (ExceptionHandling && MMI) {
+    if (MMI) {
       if (CurMBB->isLandingPad())
         addCatchInfo(I, MMI, CurMBB);
       else {
@@ -2902,7 +2898,7 @@ SelectionDAGLowering::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) {
   case Intrinsic::eh_return: {
     MachineModuleInfo *MMI = DAG.getMachineModuleInfo();
 
-    if (MMI && ExceptionHandling) {
+    if (MMI) {
       MMI->setCallsEHReturn(true);
       DAG.setRoot(DAG.getNode(ISD::EH_RETURN,
                               MVT::Other,
@@ -2925,32 +2921,27 @@ SelectionDAGLowering::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) {
    }
 
    case Intrinsic::eh_dwarf_cfa: {
-     if (ExceptionHandling) {
-       MVT::ValueType VT = getValue(I.getOperand(1)).getValueType();
-       SDOperand CfaArg;
-       if (MVT::getSizeInBits(VT) > MVT::getSizeInBits(TLI.getPointerTy()))
-         CfaArg = DAG.getNode(ISD::TRUNCATE,
-                              TLI.getPointerTy(), getValue(I.getOperand(1)));
-       else
-         CfaArg = DAG.getNode(ISD::SIGN_EXTEND,
-                              TLI.getPointerTy(), getValue(I.getOperand(1)));
-       
-       SDOperand Offset = DAG.getNode(ISD::ADD,
-                                      TLI.getPointerTy(),
-                                      DAG.getNode(ISD::FRAME_TO_ARGS_OFFSET,
-                                                  TLI.getPointerTy()),
-                                      CfaArg);
-       setValue(&I, DAG.getNode(ISD::ADD,
-                                TLI.getPointerTy(),
-                                DAG.getNode(ISD::FRAMEADDR,
-                                            TLI.getPointerTy(),
-                                            DAG.getConstant(0,
-                                                            TLI.getPointerTy())),
-                                Offset));
-     } else {
-       setValue(&I, DAG.getConstant(0, TLI.getPointerTy()));
-     }
-
+     MVT::ValueType VT = getValue(I.getOperand(1)).getValueType();
+     SDOperand CfaArg;
+     if (MVT::getSizeInBits(VT) > MVT::getSizeInBits(TLI.getPointerTy()))
+       CfaArg = DAG.getNode(ISD::TRUNCATE,
+                            TLI.getPointerTy(), getValue(I.getOperand(1)));
+     else
+       CfaArg = DAG.getNode(ISD::SIGN_EXTEND,
+                            TLI.getPointerTy(), getValue(I.getOperand(1)));
+
+     SDOperand Offset = DAG.getNode(ISD::ADD,
+                                    TLI.getPointerTy(),
+                                    DAG.getNode(ISD::FRAME_TO_ARGS_OFFSET,
+                                                TLI.getPointerTy()),
+                                    CfaArg);
+     setValue(&I, DAG.getNode(ISD::ADD,
+                              TLI.getPointerTy(),
+                              DAG.getNode(ISD::FRAMEADDR,
+                                          TLI.getPointerTy(),
+                                          DAG.getConstant(0,
+                                                          TLI.getPointerTy())),
+                              Offset));
      return 0;
   }
 
@@ -3176,7 +3167,7 @@ void SelectionDAGLowering::LowerCallTo(CallSite CS, SDOperand Callee,
     Args.push_back(Entry);
   }
 
-  if (LandingPad && ExceptionHandling && MMI) {
+  if (LandingPad && 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 +3186,7 @@ void SelectionDAGLowering::LowerCallTo(CallSite CS, SDOperand Callee,
     setValue(CS.getInstruction(), Result.first);
   DAG.setRoot(Result.second);
 
-  if (LandingPad && ExceptionHandling && MMI) {
+  if (LandingPad && 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();
@@ -4614,11 +4605,10 @@ bool SelectionDAGISel::runOnFunction(Function &Fn) {
 
   FunctionLoweringInfo FuncInfo(TLI, Fn, MF);
 
-  if (ExceptionHandling)
-    for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
-      if (InvokeInst *Invoke = dyn_cast<InvokeInst>(I->getTerminator()))
-        // Mark landing pad.
-        FuncInfo.MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
+  for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
+    if (InvokeInst *Invoke = dyn_cast<InvokeInst>(I->getTerminator()))
+      // Mark landing pad.
+      FuncInfo.MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
 
   for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
     SelectBasicBlock(I, MF, FuncInfo);
@@ -4757,7 +4747,7 @@ void SelectionDAGISel::BuildSelectionDAG(SelectionDAG &DAG, BasicBlock *LLVMBB,
 
   MachineModuleInfo *MMI = DAG.getMachineModuleInfo();
 
-  if (ExceptionHandling && MMI && BB->isLandingPad()) {
+  if (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);