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.

llvm-svn: 75379
diff --git a/llvm/lib/Target/Alpha/AsmPrinter/AlphaAsmPrinter.cpp b/llvm/lib/Target/Alpha/AsmPrinter/AlphaAsmPrinter.cpp
index 11f177d..cc278b7 100644
--- a/llvm/lib/Target/Alpha/AsmPrinter/AlphaAsmPrinter.cpp
+++ b/llvm/lib/Target/Alpha/AsmPrinter/AlphaAsmPrinter.cpp
@@ -155,7 +155,7 @@
 
   EmitAlignment(MF.getAlignment(), F);
   switch (F->getLinkage()) {
-  default: assert(0 && "Unknown linkage type!");
+  default: LLVM_UNREACHABLE( "Unknown linkage type!");
   case Function::InternalLinkage:  // Symbols default to internal.
   case Function::PrivateLinkage:
     break;