1 files changed, 71 insertions, 43 deletions

diff --git a/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp b/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
index 13d349be40b..717b07ca059 100644
--- a/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -110,8 +110,8 @@ class TwoAddressInstructionPass : public MachineFunctionPass {
   bool isProfitableToCommute(unsigned regA, unsigned regB, unsigned regC,
                              MachineInstr *MI, unsigned Dist);
 
-  bool commuteInstruction(MachineBasicBlock::iterator &mi,
-                          unsigned RegB, unsigned RegC, unsigned Dist);
+  bool commuteInstruction(MachineInstr *MI,
+                          unsigned RegBIdx, unsigned RegCIdx, unsigned Dist);
 
   bool isProfitableToConv3Addr(unsigned RegA, unsigned RegB);
 
@@ -133,6 +133,11 @@ class TwoAddressInstructionPass : public MachineFunctionPass {
                                unsigned SrcIdx, unsigned DstIdx,
                                unsigned Dist, bool shouldOnlyCommute);
 
+  bool tryInstructionCommute(MachineInstr *MI,
+                             unsigned DstOpIdx,
+                             unsigned BaseOpIdx,
+                             bool BaseOpKilled,
+                             unsigned Dist);
   void scanUses(unsigned DstReg);
 
   void processCopy(MachineInstr *MI);
@@ -645,12 +650,13 @@ isProfitableToCommute(unsigned regA, unsigned regB, unsigned regC,
 /// commuteInstruction - Commute a two-address instruction and update the basic
 /// block, distance map, and live variables if needed. Return true if it is
 /// successful.
-bool TwoAddressInstructionPass::
-commuteInstruction(MachineBasicBlock::iterator &mi,
-                   unsigned RegB, unsigned RegC, unsigned Dist) {
-  MachineInstr *MI = mi;
+bool TwoAddressInstructionPass::commuteInstruction(MachineInstr *MI,
+                                                   unsigned RegBIdx,
+                                                   unsigned RegCIdx,
+                                                   unsigned Dist) {
+  unsigned RegC = MI->getOperand(RegCIdx).getReg();
   DEBUG(dbgs() << "2addr: COMMUTING  : " << *MI);
-  MachineInstr *NewMI = TII->commuteInstruction(MI);
+  MachineInstr *NewMI = TII->commuteInstruction(MI, false, RegBIdx, RegCIdx);
 
   if (NewMI == nullptr) {
     DEBUG(dbgs() << "2addr: COMMUTING FAILED!\n");
@@ -1155,6 +1161,61 @@ rescheduleKillAboveMI(MachineBasicBlock::iterator &mi,
   return true;
 }
 
+/// Tries to commute the operand 'BaseOpIdx' and some other operand in the
+/// given machine instruction to improve opportunities for coalescing and
+/// elimination of a register to register copy.
+///
+/// 'DstOpIdx' specifies the index of MI def operand.
+/// 'BaseOpKilled' specifies if the register associated with 'BaseOpIdx'
+/// operand is killed by the given instruction.
+/// The 'Dist' arguments provides the distance of MI from the start of the
+/// current basic block and it is used to determine if it is profitable
+/// to commute operands in the instruction.
+///
+/// Returns true if the transformation happened. Otherwise, returns false.
+bool TwoAddressInstructionPass::tryInstructionCommute(MachineInstr *MI,
+                                                      unsigned DstOpIdx,
+                                                      unsigned BaseOpIdx,
+                                                      bool BaseOpKilled,
+                                                      unsigned Dist) {
+  unsigned DstOpReg = MI->getOperand(DstOpIdx).getReg();
+  unsigned BaseOpReg = MI->getOperand(BaseOpIdx).getReg();
+  unsigned OpsNum = MI->getDesc().getNumOperands();
+  unsigned OtherOpIdx = MI->getDesc().getNumDefs();
+  for (; OtherOpIdx < OpsNum; OtherOpIdx++) {
+    // The call of findCommutedOpIndices below only checks if BaseOpIdx
+    // and OtherOpIdx are commutable, it does not really searches for
+    // other commutable operands and does not change the values of passed
+    // variables.
+    if (OtherOpIdx == BaseOpIdx ||
+        !TII->findCommutedOpIndices(MI, BaseOpIdx, OtherOpIdx))
+      continue;
+
+    unsigned OtherOpReg = MI->getOperand(OtherOpIdx).getReg();
+    bool AggressiveCommute = false;
+
+    // If OtherOp dies but BaseOp does not, swap the OtherOp and BaseOp
+    // operands. This makes the live ranges of DstOp and OtherOp joinable.
+    bool DoCommute =
+        !BaseOpKilled && isKilled(*MI, OtherOpReg, MRI, TII, LIS, false);
+
+    if (!DoCommute &&
+        isProfitableToCommute(DstOpReg, BaseOpReg, OtherOpReg, MI, Dist)) {
+      DoCommute = true;
+      AggressiveCommute = true;
+    }
+
+    // If it's profitable to commute, try to do so.
+    if (DoCommute && commuteInstruction(MI, BaseOpIdx, OtherOpIdx, Dist)) {
+      ++NumCommuted;
+      if (AggressiveCommute)
+        ++NumAggrCommuted;
+      return true;
+    }
+  }
+  return false;
+}
+
 /// tryInstructionTransform - For the case where an instruction has a single
 /// pair of tied register operands, attempt some transformations that may
 /// either eliminate the tied operands or improve the opportunities for
@@ -1181,31 +1242,7 @@ tryInstructionTransform(MachineBasicBlock::iterator &mi,
   if (TargetRegisterInfo::isVirtualRegister(regA))
     scanUses(regA);
 
-  // Check if it is profitable to commute the operands.
-  unsigned SrcOp1, SrcOp2;
-  unsigned regC = 0;
-  unsigned regCIdx = ~0U;
-  bool TryCommute = false;
-  bool AggressiveCommute = false;
-  if (MI.isCommutable() && MI.getNumOperands() >= 3 &&
-      TII->findCommutedOpIndices(&MI, SrcOp1, SrcOp2)) {
-    if (SrcIdx == SrcOp1)
-      regCIdx = SrcOp2;
-    else if (SrcIdx == SrcOp2)
-      regCIdx = SrcOp1;
-
-    if (regCIdx != ~0U) {
-      regC = MI.getOperand(regCIdx).getReg();
-      if (!regBKilled && isKilled(MI, regC, MRI, TII, LIS, false))
-        // If C dies but B does not, swap the B and C operands.
-        // This makes the live ranges of A and C joinable.
-        TryCommute = true;
-      else if (isProfitableToCommute(regA, regB, regC, &MI, Dist)) {
-        TryCommute = true;
-        AggressiveCommute = true;
-      }
-    }
-  }
+  bool Commuted = tryInstructionCommute(&MI, DstIdx, SrcIdx, regBKilled, Dist);
 
   // If the instruction is convertible to 3 Addr, instead
   // of returning try 3 Addr transformation aggresively and
@@ -1215,17 +1252,8 @@ tryInstructionTransform(MachineBasicBlock::iterator &mi,
   //   addl     %esi, %edi
   //   movl     %edi, %eax
   //   ret
-  bool Commuted = false;
-
-  // If it's profitable to commute, try to do so.
-  if (TryCommute && commuteInstruction(mi, regB, regC, Dist)) {
-    Commuted = true;
-    ++NumCommuted;
-    if (AggressiveCommute)
-      ++NumAggrCommuted;
-    if (!MI.isConvertibleTo3Addr())
-      return false;
-  }
+  if (Commuted && !MI.isConvertibleTo3Addr())
+    return false;
 
   if (shouldOnlyCommute)
     return false;