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[oota-llvm.git] / lib / CodeGen / MachineBasicBlock.cpp

diff --git a/lib/CodeGen/MachineBasicBlock.cpp b/lib/CodeGen/MachineBasicBlock.cpp
index 9250577518a3765b64eaab9e1340f60a16e08675..48008537e7546887c6dea064ce2a5ee4c3017b6a 100644 (file)
--- a/lib/CodeGen/MachineBasicBlock.cpp
+++ b/lib/CodeGen/MachineBasicBlock.cpp
@@ -12,24 +12,24 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/Assembly/Writer.h"
 #include "llvm/BasicBlock.h"
 #include "llvm/CodeGen/LiveVariables.h"
 #include "llvm/CodeGen/MachineDominators.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineLoopInfo.h"
 #include "llvm/CodeGen/SlotIndexes.h"
+#include "llvm/DataLayout.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCContext.h"
-#include "llvm/Target/TargetRegisterInfo.h"
-#include "llvm/Target/TargetData.h"
-#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Target/TargetMachine.h"
-#include "llvm/Assembly/Writer.h"
-#include "llvm/ADT/SmallString.h"
-#include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/LeakDetector.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetRegisterInfo.h"
 #include <algorithm>
 using namespace llvm;
 
@@ -145,7 +145,8 @@ MachineBasicBlock::iterator MachineBasicBlock::getFirstNonPHI() {
   instr_iterator I = instr_begin(), E = instr_end();
   while (I != E && I->isPHI())
     ++I;
-  assert(!I->isInsideBundle() && "First non-phi MI cannot be inside a bundle!");
+  assert((I == E || !I->isInsideBundle()) &&
+         "First non-phi MI cannot be inside a bundle!");
   return I;
 }
 
@@ -156,7 +157,7 @@ MachineBasicBlock::SkipPHIsAndLabels(MachineBasicBlock::iterator I) {
     ++I;
   // FIXME: This needs to change if we wish to bundle labels / dbg_values
   // inside the bundle.
-  assert(!I->isInsideBundle() &&
+  assert((I == E || !I->isInsideBundle()) &&
          "First non-phi / non-label instruction is inside a bundle!");
   return I;
 }
@@ -228,7 +229,7 @@ const MachineBasicBlock *MachineBasicBlock::getLandingPadSuccessor() const {
   return 0;
 }
 
-#ifndef NDEBUG
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
 void MachineBasicBlock::dump() const {
   print(dbgs());
 }
@@ -971,6 +972,83 @@ getWeightIterator(MachineBasicBlock::const_succ_iterator I) const {
   return Weights.begin() + index;
 }
 
+/// Return whether (physical) register "Reg" has been <def>ined and not <kill>ed
+/// as of just before "MI".
+/// 
+/// Search is localised to a neighborhood of
+/// Neighborhood instructions before (searching for defs or kills) and N
+/// instructions after (searching just for defs) MI.
+MachineBasicBlock::LivenessQueryResult
+MachineBasicBlock::computeRegisterLiveness(const TargetRegisterInfo *TRI,
+                                           unsigned Reg, MachineInstr *MI,
+                                           unsigned Neighborhood) {
+  unsigned N = Neighborhood;
+  MachineBasicBlock *MBB = MI->getParent();
+
+  // Start by searching backwards from MI, looking for kills, reads or defs.
+
+  MachineBasicBlock::iterator I(MI);
+  // If this is the first insn in the block, don't search backwards.
+  if (I != MBB->begin()) {
+    do {
+      --I;
+
+      MachineOperandIteratorBase::PhysRegInfo Analysis =
+        MIOperands(I).analyzePhysReg(Reg, TRI);
+
+      if (Analysis.Defines)
+        // Outputs happen after inputs so they take precedence if both are
+        // present.
+        return Analysis.DefinesDead ? LQR_Dead : LQR_Live;
+
+      if (Analysis.Kills || Analysis.Clobbers)
+        // Register killed, so isn't live.
+        return LQR_Dead;
+
+      else if (Analysis.ReadsOverlap)
+        // Defined or read without a previous kill - live.
+        return Analysis.Reads ? LQR_Live : LQR_OverlappingLive;
+
+    } while (I != MBB->begin() && --N > 0);
+  }
+
+  // Did we get to the start of the block?
+  if (I == MBB->begin()) {
+    // If so, the register's state is definitely defined by the live-in state.
+    for (MCRegAliasIterator RAI(Reg, TRI, /*IncludeSelf=*/true);
+         RAI.isValid(); ++RAI) {
+      if (MBB->isLiveIn(*RAI))
+        return (*RAI == Reg) ? LQR_Live : LQR_OverlappingLive;
+    }
+
+    return LQR_Dead;
+  }
+
+  N = Neighborhood;
+
+  // Try searching forwards from MI, looking for reads or defs.
+  I = MachineBasicBlock::iterator(MI);
+  // If this is the last insn in the block, don't search forwards.
+  if (I != MBB->end()) {
+    for (++I; I != MBB->end() && N > 0; ++I, --N) {
+      MachineOperandIteratorBase::PhysRegInfo Analysis =
+        MIOperands(I).analyzePhysReg(Reg, TRI);
+
+      if (Analysis.ReadsOverlap)
+        // Used, therefore must have been live.
+        return (Analysis.Reads) ?
+          LQR_Live : LQR_OverlappingLive;
+
+      else if (Analysis.Clobbers || Analysis.Defines)
+        // Defined (but not read) therefore cannot have been live.
+        return LQR_Dead;
+    }
+  }
+
+  // At this point we have no idea of the liveness of the register.
+  return LQR_Unknown;
+}
+
 void llvm::WriteAsOperand(raw_ostream &OS, const MachineBasicBlock *MBB,
                           bool t) {
   OS << "BB#" << MBB->getNumber();