Make dense maps keyed on physical registers smallerusing

MRegisterInfo::getNumRegs() instead of
MRegisterInfo::FirstVirtualRegister.

Also use MRegisterInfo::is{Physical,Virtual}Register where
appropriate.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11477 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/PeepholeOptimizer.cpp

@@ -164,7 +164,7 @@ namespace {
     // getDefinition - Return the machine instruction that defines the specified
     // SSA virtual register.
     MachineInstr *getDefinition(unsigned Reg) {
-      assert(Reg >= MRegisterInfo::FirstVirtualRegister &&
+      assert(MRegisterInfo::isVirtualRegister(Reg) &&
              "use-def chains only exist for SSA registers!");
       assert(Reg - MRegisterInfo::FirstVirtualRegister < DefiningInst.size() &&
              "Unknown register number!");