[ARM] Modify codegen for memcpy intrinsic to prefer LDM/STM.

[oota-llvm.git] / lib / Target / ARM / ARMBaseInstrInfo.cpp

diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp
index 337531aaab04c259bedea93aea3fce9c5de81af8..ebfad093d85b658f9e37cfa586fc11d455a7b95d 100644 (file)
--- a/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -1219,6 +1219,60 @@ unsigned ARMBaseInstrInfo::isLoadFromStackSlotPostFE(const MachineInstr *MI,
   return MI->mayLoad() && hasLoadFromStackSlot(MI, Dummy, FrameIndex);
 }
 
+/// \brief Expands MEMCPY to either LDMIA/STMIA or LDMIA_UPD/STMID_UPD
+/// depending on whether the result is used.
+void ARMBaseInstrInfo::expandMEMCPY(MachineBasicBlock::iterator MBBI) const {
+  bool isThumb1 = Subtarget.isThumb1Only();
+  bool isThumb2 = Subtarget.isThumb2();
+  const ARMBaseInstrInfo *TII = Subtarget.getInstrInfo();
+
+  MachineInstr *MI = MBBI;
+  DebugLoc dl = MI->getDebugLoc();
+  MachineBasicBlock *BB = MI->getParent();
+
+  MachineInstrBuilder LDM, STM;
+  if (isThumb1 || !MI->getOperand(1).isDead()) {
+    LDM = BuildMI(*BB, MI, dl, TII->get(isThumb2 ? ARM::t2LDMIA_UPD
+                                                 : isThumb1 ? ARM::tLDMIA_UPD
+                                                            : ARM::LDMIA_UPD))
+             .addOperand(MI->getOperand(1));
+  } else {
+    LDM = BuildMI(*BB, MI, dl, TII->get(isThumb2 ? ARM::t2LDMIA : ARM::LDMIA));
+  }
+
+  if (isThumb1 || !MI->getOperand(0).isDead()) {
+    STM = BuildMI(*BB, MI, dl, TII->get(isThumb2 ? ARM::t2STMIA_UPD
+                                                 : isThumb1 ? ARM::tSTMIA_UPD
+                                                            : ARM::STMIA_UPD))
+             .addOperand(MI->getOperand(0));
+  } else {
+    STM = BuildMI(*BB, MI, dl, TII->get(isThumb2 ? ARM::t2STMIA : ARM::STMIA));
+  }
+
+  AddDefaultPred(LDM.addOperand(MI->getOperand(3)));
+  AddDefaultPred(STM.addOperand(MI->getOperand(2)));
+
+  // Sort the scratch registers into ascending order.
+  const TargetRegisterInfo &TRI = getRegisterInfo();
+  llvm::SmallVector<unsigned, 6> ScratchRegs;
+  for(unsigned I = 5; I < MI->getNumOperands(); ++I)
+    ScratchRegs.push_back(MI->getOperand(I).getReg());
+  std::sort(ScratchRegs.begin(), ScratchRegs.end(),
+            [&TRI](const unsigned &Reg1,
+                   const unsigned &Reg2) -> bool {
+              return TRI.getEncodingValue(Reg1) <
+                     TRI.getEncodingValue(Reg2);
+            });
+
+  for (const auto &Reg : ScratchRegs) {
+    LDM.addReg(Reg, RegState::Define);
+    STM.addReg(Reg, RegState::Kill);
+  }
+
+  BB->erase(MBBI);
+}
+
+
 bool
 ARMBaseInstrInfo::expandPostRAPseudo(MachineBasicBlock::iterator MI) const {
   MachineFunction &MF = *MI->getParent()->getParent();
@@ -1232,6 +1286,11 @@ ARMBaseInstrInfo::expandPostRAPseudo(MachineBasicBlock::iterator MI) const {
     return true;
   }
 
+  if (MI->getOpcode() == ARM::MEMCPY) {
+    expandMEMCPY(MI);
+    return true;
+  }
+
   // This hook gets to expand COPY instructions before they become
   // copyPhysReg() calls.  Look for VMOVS instructions that can legally be
   // widened to VMOVD.  We prefer the VMOVD when possible because it may be