From 65e6d4a3f84da042972671dda29134ec66940b53 Mon Sep 17 00:00:00 2001
From: Matthias Braun <matze@braunis.de>
Date: Sat, 17 Oct 2015 01:03:44 +0000
Subject: [PATCH] RegisterPressure: Unify the sparse sets in LiveRegsSet; NFC

Also do some cleanups comment improvements.

llvm-svn: 250598
---
 llvm/include/llvm/CodeGen/RegisterPressure.h | 56 ++++++++++++++------
 llvm/lib/CodeGen/RegisterPressure.cpp        | 31 ++++++-----
 2 files changed, 60 insertions(+), 27 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/RegisterPressure.h b/llvm/include/llvm/CodeGen/RegisterPressure.h
index 1903ba768dde..67ae00762b24 100644
--- a/llvm/include/llvm/CodeGen/RegisterPressure.h
+++ b/llvm/include/llvm/CodeGen/RegisterPressure.h
@@ -193,30 +193,56 @@ struct RegPressureDelta {
   }
 };
 
-/// \brief A set of live virtual registers and physical register units.
+/// A set of live virtual registers and physical register units.
 ///
-/// Virtual and physical register numbers require separate sparse sets, but most
-/// of the RegisterPressureTracker handles them uniformly.
-struct LiveRegSet {
-  SparseSet<unsigned> PhysRegs;
-  SparseSet<unsigned, VirtReg2IndexFunctor> VirtRegs;
+/// This is a wrapper around a SparseSet which deals with mapping register unit
+/// and virtual register indexes to an index usable by the sparse set.
+class LiveRegSet {
+private:
+  SparseSet<unsigned> Regs;
+  unsigned NumRegUnits;
+
+  unsigned getSparseIndexFromReg(unsigned Reg) const {
+    if (TargetRegisterInfo::isVirtualRegister(Reg))
+      return TargetRegisterInfo::virtReg2Index(Reg) + NumRegUnits;
+    assert(Reg < NumRegUnits);
+    return Reg;
+  }
+  unsigned getRegFromSparseIndex(unsigned SparseIndex) const {
+    if (SparseIndex >= NumRegUnits)
+      return TargetRegisterInfo::index2VirtReg(SparseIndex-NumRegUnits);
+    return SparseIndex;
+  }
+
+public:
+  void clear();
+  void init(const MachineRegisterInfo &MRI);
 
   bool contains(unsigned Reg) const {
-    if (TargetRegisterInfo::isVirtualRegister(Reg))
-      return VirtRegs.count(Reg);
-    return PhysRegs.count(Reg);
+    unsigned SparseIndex = getSparseIndexFromReg(Reg);
+    return Regs.count(SparseIndex);
   }
 
   bool insert(unsigned Reg) {
-    if (TargetRegisterInfo::isVirtualRegister(Reg))
-      return VirtRegs.insert(Reg).second;
-    return PhysRegs.insert(Reg).second;
+    unsigned SparseIndex = getSparseIndexFromReg(Reg);
+    return Regs.insert(SparseIndex).second;
   }
 
   bool erase(unsigned Reg) {
-    if (TargetRegisterInfo::isVirtualRegister(Reg))
-      return VirtRegs.erase(Reg);
-    return PhysRegs.erase(Reg);
+    unsigned SparseIndex = getSparseIndexFromReg(Reg);
+    return Regs.erase(SparseIndex);
+  }
+
+  size_t size() const {
+    return Regs.size();
+  }
+
+  template<typename ContainerT>
+  void appendTo(ContainerT &To) const {
+    for (unsigned I : Regs) {
+      unsigned Reg = getRegFromSparseIndex(I);
+      To.push_back(Reg);
+    }
   }
 };
 
diff --git a/llvm/lib/CodeGen/RegisterPressure.cpp b/llvm/lib/CodeGen/RegisterPressure.cpp
index 8172c558ac72..2ef23c7541de 100644
--- a/llvm/lib/CodeGen/RegisterPressure.cpp
+++ b/llvm/lib/CodeGen/RegisterPressure.cpp
@@ -157,6 +157,18 @@ void RegionPressure::openBottom(MachineBasicBlock::const_iterator PrevBottom) {
   LiveInRegs.clear();
 }
 
+void LiveRegSet::init(const MachineRegisterInfo &MRI) {
+  const TargetRegisterInfo &TRI = *MRI.getTargetRegisterInfo();
+  unsigned NumRegUnits = TRI.getNumRegs();
+  unsigned NumVirtRegs = MRI.getNumVirtRegs();
+  Regs.setUniverse(NumRegUnits + NumVirtRegs);
+  this->NumRegUnits = NumRegUnits;
+}
+
+void LiveRegSet::clear() {
+  Regs.clear();
+}
+
 const LiveRange *RegPressureTracker::getLiveRange(unsigned Reg) const {
   if (TargetRegisterInfo::isVirtualRegister(Reg))
     return &LIS->getInterval(Reg);
@@ -176,8 +188,7 @@ void RegPressureTracker::reset() {
   else
     static_cast<RegionPressure&>(P).reset();
 
-  LiveRegs.PhysRegs.clear();
-  LiveRegs.VirtRegs.clear();
+  LiveRegs.clear();
   UntiedDefs.clear();
 }
 
@@ -210,8 +221,7 @@ void RegPressureTracker::init(const MachineFunction *mf,
 
   P.MaxSetPressure = CurrSetPressure;
 
-  LiveRegs.PhysRegs.setUniverse(TRI->getNumRegUnits());
-  LiveRegs.VirtRegs.setUniverse(MRI->getNumVirtRegs());
+  LiveRegs.init(*MRI);
   if (TrackUntiedDefs)
     UntiedDefs.setUniverse(MRI->getNumVirtRegs());
 }
@@ -250,9 +260,8 @@ void RegPressureTracker::closeTop() {
     static_cast<RegionPressure&>(P).TopPos = CurrPos;
 
   assert(P.LiveInRegs.empty() && "inconsistent max pressure result");
-  P.LiveInRegs.reserve(LiveRegs.PhysRegs.size() + LiveRegs.VirtRegs.size());
-  P.LiveInRegs.append(LiveRegs.PhysRegs.begin(), LiveRegs.PhysRegs.end());
-  P.LiveInRegs.append(LiveRegs.VirtRegs.begin(), LiveRegs.VirtRegs.end());
+  P.LiveInRegs.reserve(LiveRegs.size());
+  LiveRegs.appendTo(P.LiveInRegs);
 }
 
 /// Set the boundary for the bottom of the region and summarize live outs.
@@ -263,16 +272,14 @@ void RegPressureTracker::closeBottom() {
     static_cast<RegionPressure&>(P).BottomPos = CurrPos;
 
   assert(P.LiveOutRegs.empty() && "inconsistent max pressure result");
-  P.LiveOutRegs.reserve(LiveRegs.PhysRegs.size() + LiveRegs.VirtRegs.size());
-  P.LiveOutRegs.append(LiveRegs.PhysRegs.begin(), LiveRegs.PhysRegs.end());
-  P.LiveOutRegs.append(LiveRegs.VirtRegs.begin(), LiveRegs.VirtRegs.end());
+  P.LiveOutRegs.reserve(LiveRegs.size());
+  LiveRegs.appendTo(P.LiveOutRegs);
 }
 
 /// Finalize the region boundaries and record live ins and live outs.
 void RegPressureTracker::closeRegion() {
   if (!isTopClosed() && !isBottomClosed()) {
-    assert(LiveRegs.PhysRegs.empty() && LiveRegs.VirtRegs.empty() &&
-           "no region boundary");
+    assert(LiveRegs.size() == 0 && "no region boundary");
     return;
   }
   if (!isBottomClosed())