assert(0) -> LLVM_UNREACHABLE.

Make llvm_unreachable take an optional string, thus moving the cerr<< out of
line.
LLVM_UNREACHABLE is now a simple wrapper that makes the message go away for
NDEBUG builds.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75379 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Target/TargetData.h

@@ -22,6 +22,7 @@
 
 #include "llvm/Pass.h"
 #include "llvm/Support/DataTypes.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/ADT/SmallVector.h"
 #include <string>
 
@@ -111,9 +112,8 @@ public:
   /// @note This has to exist, because this is a pass, but it should never be
   /// used.
   TargetData() : ImmutablePass(&ID) {
-    assert(0 && "ERROR: Bad TargetData ctor used.  "
-           "Tool did not specify a TargetData to use?");
-    abort();
+    llvm_report_error("ERROR: Bad TargetData ctor used.  "
+                      "Tool did not specify a TargetData to use?");
   }
 
   /// Constructs a TargetData from a specification string. See init().

include/llvm/Target/TargetInstrInfo.h

@@ -14,6 +14,7 @@
 #ifndef LLVM_TARGET_TARGETINSTRINFO_H
 #define LLVM_TARGET_TARGETINSTRINFO_H
 
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Target/TargetInstrDesc.h"
 #include "llvm/CodeGen/MachineFunction.h"
 
@@ -428,8 +429,7 @@ public:
   /// point.
   virtual void insertNoop(MachineBasicBlock &MBB, 
                           MachineBasicBlock::iterator MI) const {
-    assert(0 && "Target didn't implement insertNoop!");
-    abort();
+    LLVM_UNREACHABLE("Target didn't implement insertNoop!");
   }
 
   /// isPredicated - Returns true if the instruction is already predicated.