Teach TableGen to pre-calculate register enum values when creating the
CodeGenRegister entries. Use this information to more intelligently build
the literal register entires in the DAGISel matcher table. Specifically,
use a single-byte OPC_EmitRegister entry for registers with a value of
less than 256 and OPC_EmitRegister2 entry for registers with a larger value.

rdar://9066491

llvm-svn: 127456
diff --git a/llvm/utils/TableGen/DAGISelEmitter.cpp b/llvm/utils/TableGen/DAGISelEmitter.cpp
index dee8f77..d66ae96 100644
--- a/llvm/utils/TableGen/DAGISelEmitter.cpp
+++ b/llvm/utils/TableGen/DAGISelEmitter.cpp
@@ -148,12 +148,8 @@
   Matcher *TheMatcher = new ScopeMatcher(&PatternMatchers[0],
                                          PatternMatchers.size());
 
-  CodeGenTarget Target(Records);
-  const std::vector<CodeGenRegister> &Registers = Target.getRegisters();
-  bool useEmitRegister2 = Registers.size() > 255;
-
   TheMatcher = OptimizeMatcher(TheMatcher, CGP);
   //Matcher->dump();
-  EmitMatcherTable(TheMatcher, CGP, useEmitRegister2, OS);
+  EmitMatcherTable(TheMatcher, CGP, OS);
   delete TheMatcher;
 }