X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FVirtRegMap.cpp;h=e0aa4053987c225a3545dbdea6f45daf1542e80b;hb=3e2346341cc7407bb895ddb13e43d512713e8a35;hp=6343e8a35299660772b93ce00f848ffcf3f3ad56;hpb=e617ccb80da76821379bbff4a2fdcd09e8401e8b;p=oota-llvm.git

diff --git a/lib/CodeGen/VirtRegMap.cpp b/lib/CodeGen/VirtRegMap.cpp
index 6343e8a3529..e0aa4053987 100644
--- a/lib/CodeGen/VirtRegMap.cpp
+++ b/lib/CodeGen/VirtRegMap.cpp
@@ -17,23 +17,25 @@
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "regalloc"
-#include "VirtRegMap.h"
+#include "llvm/CodeGen/VirtRegMap.h"
 #include "LiveDebugVariables.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/Statistic.h"
 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
+#include "llvm/CodeGen/LiveStackAnalysis.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/Passes.h"
-#include "llvm/Target/TargetMachine.h"
-#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/IR/Function.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/STLExtras.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetRegisterInfo.h"
 #include <algorithm>
 using namespace llvm;
 
@@ -76,15 +78,22 @@ unsigned VirtRegMap::createSpillSlot(const TargetRegisterClass *RC) {
   return SS;
 }
 
-unsigned VirtRegMap::getRegAllocPref(unsigned virtReg) {
-  std::pair<unsigned, unsigned> Hint = MRI->getRegAllocationHint(virtReg);
-  unsigned physReg = Hint.second;
-  if (TargetRegisterInfo::isVirtualRegister(physReg) && hasPhys(physReg))
-    physReg = getPhys(physReg);
-  if (Hint.first == 0)
-    return (TargetRegisterInfo::isPhysicalRegister(physReg))
-      ? physReg : 0;
-  return TRI->ResolveRegAllocHint(Hint.first, physReg, *MF);
+bool VirtRegMap::hasPreferredPhys(unsigned VirtReg) {
+  unsigned Hint = MRI->getSimpleHint(VirtReg);
+  if (!Hint)
+    return 0;
+  if (TargetRegisterInfo::isVirtualRegister(Hint))
+    Hint = getPhys(Hint);
+  return getPhys(VirtReg) == Hint;
+}
+
+bool VirtRegMap::hasKnownPreference(unsigned VirtReg) {
+  std::pair<unsigned, unsigned> Hint = MRI->getRegAllocationHint(VirtReg);
+  if (TargetRegisterInfo::isPhysicalRegister(Hint.second))
+    return true;
+  if (TargetRegisterInfo::isVirtualRegister(Hint.second))
+    return hasPhys(Hint.second);
+  return false;
 }
 
 int VirtRegMap::assignVirt2StackSlot(unsigned virtReg) {
@@ -126,9 +135,11 @@ void VirtRegMap::print(raw_ostream &OS, const Module*) const {
   OS << '\n';
 }
 
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 void VirtRegMap::dump() const {
   print(dbgs());
 }
+#endif
 
 //===----------------------------------------------------------------------===//
 //                              VirtRegRewriter
@@ -169,6 +180,7 @@ INITIALIZE_PASS_BEGIN(VirtRegRewriter, "virtregrewriter",
 INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
 INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
 INITIALIZE_PASS_DEPENDENCY(LiveDebugVariables)
+INITIALIZE_PASS_DEPENDENCY(LiveStacks)
 INITIALIZE_PASS_DEPENDENCY(VirtRegMap)
 INITIALIZE_PASS_END(VirtRegRewriter, "virtregrewriter",
                     "Virtual Register Rewriter", false, false)
@@ -181,6 +193,8 @@ void VirtRegRewriter::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addRequired<SlotIndexes>();
   AU.addPreserved<SlotIndexes>();
   AU.addRequired<LiveDebugVariables>();
+  AU.addRequired<LiveStacks>();
+  AU.addPreserved<LiveStacks>();
   AU.addRequired<VirtRegMap>();
   MachineFunctionPass::getAnalysisUsage(AU);
 }
@@ -251,18 +265,36 @@ void VirtRegRewriter::rewrite() {
   SmallVector<unsigned, 8> SuperDeads;
   SmallVector<unsigned, 8> SuperDefs;
   SmallVector<unsigned, 8> SuperKills;
-#ifndef NDEBUG
-  BitVector Reserved = TRI->getReservedRegs(*MF);
-#endif
+  SmallPtrSet<const MachineInstr *, 4> NoReturnInsts;
 
   for (MachineFunction::iterator MBBI = MF->begin(), MBBE = MF->end();
        MBBI != MBBE; ++MBBI) {
     DEBUG(MBBI->print(dbgs(), Indexes));
+    bool IsExitBB = MBBI->succ_empty();
     for (MachineBasicBlock::instr_iterator
            MII = MBBI->instr_begin(), MIE = MBBI->instr_end(); MII != MIE;) {
       MachineInstr *MI = MII;
       ++MII;
 
+      // Check if this instruction is a call to a noreturn function.
+      // If so, all the definitions set by this instruction can be ignored.
+      if (IsExitBB && MI->isCall())
+        for (MachineInstr::mop_iterator MOI = MI->operands_begin(),
+               MOE = MI->operands_end(); MOI != MOE; ++MOI) {
+          MachineOperand &MO = *MOI;
+          if (!MO.isGlobal())
+            continue;
+          const Function *Func = dyn_cast<Function>(MO.getGlobal());
+          if (!Func || !Func->hasFnAttribute(Attribute::NoReturn) ||
+              // We need to keep correct unwind information
+              // even if the function will not return, since the
+              // runtime may need it.
+              !Func->hasFnAttribute(Attribute::NoUnwind))
+            continue;
+          NoReturnInsts.insert(MI);
+          break;
+        }
+
       for (MachineInstr::mop_iterator MOI = MI->operands_begin(),
            MOE = MI->operands_end(); MOI != MOE; ++MOI) {
         MachineOperand &MO = *MOI;
@@ -277,7 +309,7 @@ void VirtRegRewriter::rewrite() {
         unsigned PhysReg = VRM->getPhys(VirtReg);
         assert(PhysReg != VirtRegMap::NO_PHYS_REG &&
                "Instruction uses unmapped VirtReg");
-        assert(!Reserved.test(PhysReg) && "Reserved register assignment");
+        assert(!MRI->isReserved(PhysReg) && "Reserved register assignment");
 
         // Preserve semantics of sub-register operands.
         if (MO.getSubReg()) {
@@ -343,7 +375,25 @@ void VirtRegRewriter::rewrite() {
   }
 
   // Tell MRI about physical registers in use.
-  for (unsigned Reg = 1, RegE = TRI->getNumRegs(); Reg != RegE; ++Reg)
-    if (!MRI->reg_nodbg_empty(Reg))
-      MRI->setPhysRegUsed(Reg);
+  if (NoReturnInsts.empty()) {
+    for (unsigned Reg = 1, RegE = TRI->getNumRegs(); Reg != RegE; ++Reg)
+      if (!MRI->reg_nodbg_empty(Reg))
+        MRI->setPhysRegUsed(Reg);
+  } else {
+    for (unsigned Reg = 1, RegE = TRI->getNumRegs(); Reg != RegE; ++Reg) {
+      if (MRI->reg_nodbg_empty(Reg))
+        continue;
+      // Check if this register has a use that will impact the rest of the
+      // code. Uses in debug and noreturn instructions do not impact the
+      // generated code.
+      for (MachineRegisterInfo::reg_nodbg_iterator It =
+             MRI->reg_nodbg_begin(Reg),
+             EndIt = MRI->reg_nodbg_end(); It != EndIt; ++It) {
+        if (!NoReturnInsts.count(&(*It))) {
+          MRI->setPhysRegUsed(Reg);
+          break;
+        }
+      }
+    }
+  }
 }