[llvm-extract] support unnamed bbs.

Author: Yilin Li

llvm/include/llvm/IR/Value.h

@@ -290,9 +290,7 @@ class Value {
   /// \note It is an error to call V->takeName(V).
   void takeName(Value *V);
 
-#ifndef NDEBUG
   std::string getNameOrAsOperand() const;
-#endif
 
   /// Change all uses of this to point to a new Value.
   ///

llvm/lib/IR/Value.cpp

@@ -440,7 +440,6 @@ void Value::takeName(Value *V) {
     ST->reinsertValue(this);
 }
 
-#ifndef NDEBUG
 std::string Value::getNameOrAsOperand() const {
   if (!getName().empty())
     return std::string(getName());
@@ -450,7 +449,6 @@ std::string Value::getNameOrAsOperand() const {
   printAsOperand(OS, false);
   return OS.str();
 }
-#endif
 
 void Value::assertModuleIsMaterializedImpl() const {
 #ifndef NDEBUG

llvm/tools/llvm-extract/llvm-extract.cpp

@@ -90,10 +90,13 @@ static cl::list<std::string> ExtractBlocks(
         "Each pair will create a function.\n"
         "If multiple basic blocks are specified in one pair,\n"
         "the first block in the sequence should dominate the rest.\n"
+        "If an unnamed basic block is to be extracted,\n"
+        "'%' should be added before the basic block variable names.\n"
         "eg:\n"
         "  --bb=f:bb1;bb2 will extract one function with both bb1 and bb2;\n"
         "  --bb=f:bb1 --bb=f:bb2 will extract two functions, one with bb1, one "
-        "with bb2."),
+        "with bb2.\n"
+        "  --bb=f:%1 will extract one function with basic block 1;"),
     cl::value_desc("function:bb1[;bb2...]"), cl::cat(ExtractCat));
 
 // ExtractAlias - The alias to extract from the module.
@@ -356,7 +359,7 @@ int main(int argc, char **argv) {
         // The function has been materialized, so add its matching basic blocks
         // to the block extractor list, or fail if a name is not found.
         auto Res = llvm::find_if(*P.first, [&](const BasicBlock &BB) {
-          return BB.getName() == BBName;
+          return BB.getNameOrAsOperand() == BBName;
         });
         if (Res == P.first->end()) {
           errs() << argv[0] << ": function " << P.first->getName()