[tablegen] Improve performance on *GenRegisterInfo.inc by replacing S…

…parseVector with BitVector. NFC

Summary: Generating X86GenRegisterInfo.inc and AArch64GenRegisterInfo.inc is 8-9% faster on my build.

Reviewers: bogner, javed.absar

Reviewed By: bogner

Subscribers: llvm-commits, kristof.beyls

Differential Revision: https://reviews.llvm.org/D47907

llvm-svn: 334337

llvm/utils/TableGen/CodeGenRegisters.cpp

@@ -21,7 +21,6 @@
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/SparseBitVector.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringRef.h"
@@ -1635,9 +1634,10 @@ static void computeUberWeights(std::vector<UberRegSet> &UberSets,
 static bool normalizeWeight(CodeGenRegister *Reg,
                             std::vector<UberRegSet> &UberSets,
                             std::vector<UberRegSet*> &RegSets,
-                            SparseBitVector<> &NormalRegs,
+                            BitVector &NormalRegs,
                             CodeGenRegister::RegUnitList &NormalUnits,
                             CodeGenRegBank &RegBank) {
+  NormalRegs.resize(std::max(Reg->EnumValue + 1, NormalRegs.size()));
   if (NormalRegs.test(Reg->EnumValue))
     return false;
   NormalRegs.set(Reg->EnumValue);
@@ -1711,7 +1711,7 @@ void CodeGenRegBank::computeRegUnitWeights() {
     Changed = false;
     for (auto &Reg : Registers) {
       CodeGenRegister::RegUnitList NormalUnits;
-      SparseBitVector<> NormalRegs;
+      BitVector NormalRegs;
       Changed |= normalizeWeight(&Reg, UberSets, RegSets, NormalRegs,
                                  NormalUnits, *this);
     }