X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FRegisterClassInfo.cpp;h=ab33672d41f3839022fa0fdd8031906602e674be;hb=6de0a12927845ca49cd5cb1da9206fe503b565ec;hp=078a0df9151a4541b1c30aa8f6abba61e06ace41;hpb=d04a8d4b33ff316ca4cf961e06c9e312eff8e64f;p=oota-llvm.git

diff --git a/lib/CodeGen/RegisterClassInfo.cpp b/lib/CodeGen/RegisterClassInfo.cpp
index 078a0df9151..ab33672d41f 100644
--- a/lib/CodeGen/RegisterClassInfo.cpp
+++ b/lib/CodeGen/RegisterClassInfo.cpp
@@ -8,42 +8,46 @@
 //===----------------------------------------------------------------------===//
 //
 // This file implements the RegisterClassInfo class which provides dynamic
-// information about target register classes. Callee saved and reserved
-// registers depends on calling conventions and other dynamic information, so
-// some things cannot be determined statically.
+// information about target register classes. Callee-saved vs. caller-saved and
+// reserved registers depend on calling conventions and other dynamic
+// information, so some things cannot be determined statically.
 //
 //===----------------------------------------------------------------------===//
 
-#define DEBUG_TYPE "regalloc"
 #include "llvm/CodeGen/RegisterClassInfo.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
-#include "llvm/Target/TargetMachine.h"
 
 using namespace llvm;
 
+#define DEBUG_TYPE "regalloc"
+
 static cl::opt<unsigned>
 StressRA("stress-regalloc", cl::Hidden, cl::init(0), cl::value_desc("N"),
          cl::desc("Limit all regclasses to N registers"));
 
-RegisterClassInfo::RegisterClassInfo() : Tag(0), MF(0), TRI(0), CalleeSaved(0)
-{}
+RegisterClassInfo::RegisterClassInfo()
+  : Tag(0), MF(nullptr), TRI(nullptr), CalleeSaved(nullptr) {}
 
 void RegisterClassInfo::runOnMachineFunction(const MachineFunction &mf) {
   bool Update = false;
   MF = &mf;
 
   // Allocate new array the first time we see a new target.
-  if (MF->getTarget().getRegisterInfo() != TRI) {
-    TRI = MF->getTarget().getRegisterInfo();
+  if (MF->getSubtarget().getRegisterInfo() != TRI) {
+    TRI = MF->getSubtarget().getRegisterInfo();
     RegClass.reset(new RCInfo[TRI->getNumRegClasses()]);
+    unsigned NumPSets = TRI->getNumRegPressureSets();
+    PSetLimits.reset(new unsigned[NumPSets]);
+    std::fill(&PSetLimits[0], &PSetLimits[NumPSets], 0);
     Update = true;
   }
 
   // Does this MF have different CSRs?
+  assert(TRI && "no register info set");
   const MCPhysReg *CSR = TRI->getCalleeSavedRegs(MF);
   if (Update || CSR != CalleeSaved) {
     // Build a CSRNum map. Every CSR alias gets an entry pointing to the last
@@ -73,6 +77,7 @@ void RegisterClassInfo::runOnMachineFunction(const MachineFunction &mf) {
 /// registers filtered out. Volatile registers come first followed by CSR
 /// aliases ordered according to the CSR order specified by the target.
 void RegisterClassInfo::compute(const TargetRegisterClass *RC) const {
+  assert(RC && "no register class given");
   RCInfo &RCI = RegClass[RC->getID()];
 
   // Raw register count, including all reserved regs.
@@ -83,6 +88,9 @@ void RegisterClassInfo::compute(const TargetRegisterClass *RC) const {
 
   unsigned N = 0;
   SmallVector<MCPhysReg, 16> CSRAlias;
+  unsigned MinCost = 0xff;
+  unsigned LastCost = ~0u;
+  unsigned LastCostChange = 0;
 
   // FIXME: Once targets reserve registers instead of removing them from the
   // allocation order, we can simply use begin/end here.
@@ -92,17 +100,31 @@ void RegisterClassInfo::compute(const TargetRegisterClass *RC) const {
     // Remove reserved registers from the allocation order.
     if (Reserved.test(PhysReg))
       continue;
+    unsigned Cost = TRI->getCostPerUse(PhysReg);
+    MinCost = std::min(MinCost, Cost);
+
     if (CSRNum[PhysReg])
       // PhysReg aliases a CSR, save it for later.
       CSRAlias.push_back(PhysReg);
-    else
+    else {
+      if (Cost != LastCost)
+        LastCostChange = N;
       RCI.Order[N++] = PhysReg;
+      LastCost = Cost;
+    }
   }
   RCI.NumRegs = N + CSRAlias.size();
   assert (RCI.NumRegs <= NumRegs && "Allocation order larger than regclass");
 
   // CSR aliases go after the volatile registers, preserve the target's order.
-  std::copy(CSRAlias.begin(), CSRAlias.end(), &RCI.Order[N]);
+  for (unsigned i = 0, e = CSRAlias.size(); i != e; ++i) {
+    unsigned PhysReg = CSRAlias[i];
+    unsigned Cost = TRI->getCostPerUse(PhysReg);
+    if (Cost != LastCost)
+      LastCostChange = N;
+    RCI.Order[N++] = PhysReg;
+    LastCost = Cost;
+  }
 
   // Register allocator stress test.  Clip register class to N registers.
   if (StressRA && RCI.NumRegs > StressRA)
@@ -113,8 +135,11 @@ void RegisterClassInfo::compute(const TargetRegisterClass *RC) const {
     if (Super != RC && getNumAllocatableRegs(Super) > RCI.NumRegs)
       RCI.ProperSubClass = true;
 
+  RCI.MinCost = uint8_t(MinCost);
+  RCI.LastCostChange = LastCostChange;
+
   DEBUG({
-    dbgs() << "AllocationOrder(" << RC->getName() << ") = [";
+    dbgs() << "AllocationOrder(" << TRI->getRegClassName(RC) << ") = [";
     for (unsigned I = 0; I != RCI.NumRegs; ++I)
       dbgs() << ' ' << PrintReg(RCI.Order[I], TRI);
     dbgs() << (RCI.ProperSubClass ? " ] (sub-class)\n" : " ]\n");
@@ -124,3 +149,32 @@ void RegisterClassInfo::compute(const TargetRegisterClass *RC) const {
   RCI.Tag = Tag;
 }
 
+/// This is not accurate because two overlapping register sets may have some
+/// nonoverlapping reserved registers. However, computing the allocation order
+/// for all register classes would be too expensive.
+unsigned RegisterClassInfo::computePSetLimit(unsigned Idx) const {
+  const TargetRegisterClass *RC = nullptr;
+  unsigned NumRCUnits = 0;
+  for (TargetRegisterInfo::regclass_iterator
+         RI = TRI->regclass_begin(), RE = TRI->regclass_end(); RI != RE; ++RI) {
+    const int *PSetID = TRI->getRegClassPressureSets(*RI);
+    for (; *PSetID != -1; ++PSetID) {
+      if ((unsigned)*PSetID == Idx)
+        break;
+    }
+    if (*PSetID == -1)
+      continue;
+
+    // Found a register class that counts against this pressure set.
+    // For efficiency, only compute the set order for the largest set.
+    unsigned NUnits = TRI->getRegClassWeight(*RI).WeightLimit;
+    if (!RC || NUnits > NumRCUnits) {
+      RC = *RI;
+      NumRCUnits = NUnits;
+    }
+  }
+  compute(RC);
+  unsigned NReserved = RC->getNumRegs() - getNumAllocatableRegs(RC);
+  return TRI->getRegPressureSetLimit(Idx)
+    - TRI->getRegClassWeight(RC).RegWeight * NReserved;
+}