Reverse sense of unwind-tables option. This means

stack tracebacks on Darwin x86-64 won't work by default;
nevertheless, everybody but me thinks this is a good idea.

llvm-svn: 49663

include/llvm/Target/TargetOptions.h

@@ -74,10 +74,9 @@ namespace llvm {
   /// be emitted.
   extern bool ExceptionHandling;
 
-  /// UnwindTablesOptional - This flag indicates that unwind tables need not
-  /// be emitted for all functions.  Exception handling may still require them
-  /// for some functions.
-  extern bool UnwindTablesOptional;
+  /// UnwindTablesMandatory - This flag indicates that unwind tables should
+  /// be emitted for all functions.
+  extern bool UnwindTablesMandatory;
 
   /// PerformTailCallOpt - This flag is enabled when -tailcallopt is specified
   /// on the commandline. When the flag is on, the target will perform tail call

lib/CodeGen/DwarfWriter.cpp

@@ -2906,10 +2906,10 @@ private:
     // If there are no calls then you can't unwind.  This may mean we can
     // omit the EH Frame, but some environments do not handle weak absolute
     // symbols.  
-    // If UnwindTablesOptional is not set we cannot do this optimization; the
+    // If UnwindTablesMandatory is set we cannot do this optimization; the
     // unwind info is to be available for non-EH uses.
     if (!EHFrameInfo.hasCalls &&
-        UnwindTablesOptional &&
+        !UnwindTablesMandatory &&
         ((linkage != Function::WeakLinkage && 
           linkage != Function::LinkOnceLinkage) ||
          !TAI->getWeakDefDirective() ||
@@ -3432,7 +3432,7 @@ public:
       // See if we need frame move info.
       if (MMI->hasDebugInfo() || 
           !MF->getFunction()->doesNotThrow() ||
-          !UnwindTablesOptional)
+          UnwindTablesMandatory)
         shouldEmitMoves = true;
 
       if (shouldEmitMoves || shouldEmitTable)

lib/Target/PowerPC/PPCRegisterInfo.cpp

@@ -949,7 +949,7 @@ PPCRegisterInfo::emitPrologue(MachineFunction &MF) const {
   MachineModuleInfo *MMI = MFI->getMachineModuleInfo();
   bool needsFrameMoves = (MMI && MMI->hasDebugInfo()) ||
        !MF.getFunction()->doesNotThrow() ||
-       !UnwindTablesOptional;
+       UnwindTablesMandatory;
   
   // Prepare for frame info.
   unsigned FrameLabelId = 0;

lib/Target/TargetMachine.cpp

@@ -31,7 +31,7 @@ namespace llvm {
   bool UseSoftFloat;
   bool NoZerosInBSS;
   bool ExceptionHandling;
-  bool UnwindTablesOptional;
+  bool UnwindTablesMandatory;
   Reloc::Model RelocationModel;
   CodeModel::Model CMModel;
   bool PerformTailCallOpt;
@@ -85,9 +85,9 @@ namespace {
                cl::location(ExceptionHandling),
                cl::init(false));
   cl::opt<bool, true>
-  DisableUnwindTables("unwind-tables-optional",
-               cl::desc("Generate unwinding tables only for functions that require them"),
-               cl::location(UnwindTablesOptional),
+  EnableUnwindTables("unwind-tables",
+               cl::desc("Generate unwinding tables for all functions"),
+               cl::location(UnwindTablesMandatory),
                cl::init(false));
 
   cl::opt<llvm::Reloc::Model, true>

lib/Target/X86/X86RegisterInfo.cpp

@@ -506,7 +506,7 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const {
   MachineBasicBlock::iterator MBBI = MBB.begin();
   bool needsFrameMoves = (MMI && MMI->hasDebugInfo()) || 
                           !Fn->doesNotThrow() ||
-                          !UnwindTablesOptional;
+                          UnwindTablesMandatory;
   
   // Prepare for frame info.
   unsigned FrameLabelId = 0;