MachineBasicBlock: Add liveins() method returning an iterator_range

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

diff --git a/lib/CodeGen/DeadMachineInstructionElim.cpp b/lib/CodeGen/DeadMachineInstructionElim.cpp
index bbb4da8330598d6bbb7a40964f071c96caa224e8..8bb548228c221db0f373bdad0ea094c7f27a3973 100644 (file)
--- a/lib/CodeGen/DeadMachineInstructionElim.cpp
+++ b/lib/CodeGen/DeadMachineInstructionElim.cpp
@@ -11,7 +11,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-#define DEBUG_TYPE "codegen-dce"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
@@ -20,9 +19,12 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
+
 using namespace llvm;
 
+#define DEBUG_TYPE "codegen-dce"
+
 STATISTIC(NumDeletes,          "Number of dead instructions deleted");
 
 namespace {
@@ -57,9 +59,13 @@ bool DeadMachineInstructionElim::isDead(const MachineInstr *MI) const {
   if (MI->isInlineAsm())
     return false;
 
+  // Don't delete frame allocation labels.
+  if (MI->getOpcode() == TargetOpcode::LOCAL_ESCAPE)
+    return false;
+
   // Don't delete instructions with side effects.
   bool SawStore = false;
-  if (!MI->isSafeToMove(TII, 0, SawStore) && !MI->isPHI())
+  if (!MI->isSafeToMove(nullptr, SawStore) && !MI->isPHI())
     return false;
 
   // Examine each operand.
@@ -84,65 +90,45 @@ bool DeadMachineInstructionElim::isDead(const MachineInstr *MI) const {
 }
 
 bool DeadMachineInstructionElim::runOnMachineFunction(MachineFunction &MF) {
+  if (skipOptnoneFunction(*MF.getFunction()))
+    return false;
+
   bool AnyChanges = false;
   MRI = &MF.getRegInfo();
-  TRI = MF.getTarget().getRegisterInfo();
-  TII = MF.getTarget().getInstrInfo();
+  TRI = MF.getSubtarget().getRegisterInfo();
+  TII = MF.getSubtarget().getInstrInfo();
 
   // Loop over all instructions in all blocks, from bottom to top, so that it's
   // more likely that chains of dependent but ultimately dead instructions will
   // be cleaned up.
-  for (MachineFunction::reverse_iterator I = MF.rbegin(), E = MF.rend();
-       I != E; ++I) {
-    MachineBasicBlock *MBB = &*I;
-
+  for (MachineBasicBlock &MBB : make_range(MF.rbegin(), MF.rend())) {
     // Start out assuming that reserved registers are live out of this block.
     LivePhysRegs = MRI->getReservedRegs();
 
     // Add live-ins from sucessors to LivePhysRegs. Normally, physregs are not
     // live across blocks, but some targets (x86) can have flags live out of a
     // block.
-    for (MachineBasicBlock::succ_iterator S = MBB->succ_begin(),
-           E = MBB->succ_end(); S != E; S++)
-      for (MachineBasicBlock::livein_iterator LI = (*S)->livein_begin();
-           LI != (*S)->livein_end(); LI++)
-        LivePhysRegs.set(*LI);
+    for (MachineBasicBlock::succ_iterator S = MBB.succ_begin(),
+           E = MBB.succ_end(); S != E; S++)
+      for (unsigned LI : (*S)->liveins())
+        LivePhysRegs.set(LI);
 
     // Now scan the instructions and delete dead ones, tracking physreg
     // liveness as we go.
-    for (MachineBasicBlock::reverse_iterator MII = MBB->rbegin(),
-         MIE = MBB->rend(); MII != MIE; ) {
+    for (MachineBasicBlock::reverse_iterator MII = MBB.rbegin(),
+         MIE = MBB.rend(); MII != MIE; ) {
       MachineInstr *MI = &*MII;
 
       // If the instruction is dead, delete it!
       if (isDead(MI)) {
         DEBUG(dbgs() << "DeadMachineInstructionElim: DELETING: " << *MI);
         // It is possible that some DBG_VALUE instructions refer to this
-        // instruction.  Examine each def operand for such references;
-        // if found, mark the DBG_VALUE as undef (but don't delete it).
-        for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
-          const MachineOperand &MO = MI->getOperand(i);
-          if (!MO.isReg() || !MO.isDef())
-            continue;
-          unsigned Reg = MO.getReg();
-          if (!TargetRegisterInfo::isVirtualRegister(Reg))
-            continue;
-          MachineRegisterInfo::use_iterator nextI;
-          for (MachineRegisterInfo::use_iterator I = MRI->use_begin(Reg),
-               E = MRI->use_end(); I!=E; I=nextI) {
-            nextI = std::next(I);  // I is invalidated by the setReg
-            MachineOperand& Use = I.getOperand();
-            MachineInstr *UseMI = Use.getParent();
-            if (UseMI==MI)
-              continue;
-            assert(Use.isDebug());
-            UseMI->getOperand(0).setReg(0U);
-          }
-        }
+        // instruction.  They get marked as undef and will be deleted
+        // in the live debug variable analysis.
+        MI->eraseFromParentAndMarkDBGValuesForRemoval();
         AnyChanges = true;
-        MI->eraseFromParent();
         ++NumDeletes;
-        MIE = MBB->rend();
+        MIE = MBB.rend();
         // MII is now pointing to the next instruction to process,
         // so don't increment it.
         continue;