Refactor some code out of MachineSink into a MachineInstr query.

llvm-svn: 48311

llvm/include/llvm/CodeGen/MachineInstr.h

@@ -22,6 +22,7 @@
 namespace llvm {
 
 class TargetInstrDesc;
+class TargetInstrInfo;
 class TargetRegisterInfo;
 
 template <typename T> struct ilist_traits;
@@ -229,10 +230,15 @@ public:
   bool addRegisterDead(unsigned IncomingReg, const TargetRegisterInfo *RegInfo,
                        bool AddIfNotFound = false);
 
-  /// copyKillDeadInfo - copies killed/dead information from one instr to another
+  /// copyKillDeadInfo - Copies killed/dead information from one instr to another
   void copyKillDeadInfo(MachineInstr *OldMI,
                         const TargetRegisterInfo *RegInfo);
 
+  /// isSafeToMove - Return true if it is safe to this instruction. If SawStore
+  /// true, it means there is a store (or call) between the instruction the
+  /// localtion and its intended destination.
+  bool isSafeToMove(const TargetInstrInfo *TII, bool &SawStore);
+
   //
   // Debugging support
   //

llvm/lib/CodeGen/MachineInstr.cpp

@@ -628,16 +628,46 @@ void MachineInstr::copyKillDeadInfo(const MachineInstr *MI) {
 /// copyPredicates - Copies predicate operand(s) from MI.
 void MachineInstr::copyPredicates(const MachineInstr *MI) {
   const TargetInstrDesc &TID = MI->getDesc();
-  if (TID.isPredicable()) {
-    for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
-      if (TID.OpInfo[i].isPredicate()) {
-        // Predicated operands must be last operands.
-        addOperand(MI->getOperand(i));
-      }
+  if (!TID.isPredicable())
+    return;
+  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+    if (TID.OpInfo[i].isPredicate()) {
+      // Predicated operands must be last operands.
+      addOperand(MI->getOperand(i));
     }
   }
 }
 
+/// isSafeToMove - Return true if it is safe to this instruction. If SawStore
+/// true, it means there is a store (or call) between the instruction the
+/// localtion and its intended destination.
+bool MachineInstr::isSafeToMove(const TargetInstrInfo *TII, bool &SawStore) {
+  // Ignore stuff that we obviously can't move.
+  if (TID->mayStore() || TID->isCall()) {
+    SawStore = true;
+    return false;
+  }
+  if (TID->isReturn() || TID->isBranch() || TID->hasUnmodeledSideEffects())
+    return false;
+
+  // See if this instruction does a load.  If so, we have to guarantee that the
+  // loaded value doesn't change between the load and the its intended
+  // destination. The check for isInvariantLoad gives the targe the chance to
+  // classify the load as always returning a constant, e.g. a constant pool
+  // load.
+  if (TID->mayLoad() && !TII->isInvariantLoad(this)) {
+    // Otherwise, this is a real load.  If there is a store between the load and
+    // end of block, we can't sink the load.
+    //
+    // FIXME: we can't do this transformation until we know that the load is
+    // not volatile, and machineinstrs don't keep this info. :(
+    //
+    //if (SawStore) 
+    return false;
+  }
+  return true;
+}
+
 void MachineInstr::dump() const {
   cerr << "  " << *this;
 }

llvm/lib/CodeGen/MachineSink.cpp

@@ -132,30 +132,9 @@ bool MachineSinking::ProcessBlock(MachineBasicBlock &MBB) {
 /// SinkInstruction - Determine whether it is safe to sink the specified machine
 /// instruction out of its current block into a successor.
 bool MachineSinking::SinkInstruction(MachineInstr *MI, bool &SawStore) {
-  const TargetInstrDesc &TID = MI->getDesc();
-  
-  // Ignore stuff that we obviously can't sink.
-  if (TID.mayStore() || TID.isCall()) {
-    SawStore = true;
+  // Check if it's safe to move the instruction.
+  if (!MI->isSafeToMove(TII, SawStore))
     return false;
-  }
-  if (TID.isReturn() || TID.isBranch() || TID.hasUnmodeledSideEffects())
-    return false;
-
-  // See if this instruction does a load.  If so, we have to guarantee that the
-  // loaded value doesn't change between the load and the end of block.  The
-  // check for isInvariantLoad gives the targe the chance to classify the load
-  // as always returning a constant, e.g. a constant pool load.
-  if (TID.mayLoad() && !TII->isInvariantLoad(MI)) {
-    // Otherwise, this is a real load.  If there is a store between the load and
-    // end of block, we can't sink the load.
-    //
-    // FIXME: we can't do this transformation until we know that the load is
-    // not volatile, and machineinstrs don't keep this info. :(
-    //
-    //if (SawStore) 
-    return false;
-  }
   
   // FIXME: This should include support for sinking instructions within the
   // block they are currently in to shorten the live ranges.  We often get