Add GPRPair Register class to ARM.

Some instructions in ARM require 2 even-odd paired GPRs. This
patch adds support for such register class.

Patch by Weiming Zhao!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166816 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 45 insertions, 0 deletions

diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp
index b5c6159d3a..3c7bb24f42 100644
--- a/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -702,6 +702,8 @@ void ARMBaseInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
     Opc = ARM::VMOVD, BeginIdx = ARM::dsub_0, SubRegs = 3;
   else if (ARM::DQuadRegClass.contains(DestReg, SrcReg))
     Opc = ARM::VMOVD, BeginIdx = ARM::dsub_0, SubRegs = 4;
+  else if (ARM::GPRPairRegClass.contains(DestReg, SrcReg))
+    Opc = ARM::MOVr, BeginIdx = ARM::gsub_0, SubRegs = 2;
 
   else if (ARM::DPairSpcRegClass.contains(DestReg, SrcReg))
     Opc = ARM::VMOVD, BeginIdx = ARM::dsub_0, SubRegs = 2, Spacing = 2;
@@ -791,6 +793,13 @@ storeRegToStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
         AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::VSTRD))
                    .addReg(SrcReg, getKillRegState(isKill))
                    .addFrameIndex(FI).addImm(0).addMemOperand(MMO));
+      } else if (ARM::GPRPairRegClass.hasSubClassEq(RC)) {
+        MachineInstrBuilder MIB =
+          AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::STMIA))
+                       .addFrameIndex(FI))
+                       .addMemOperand(MMO);
+          MIB = AddDReg(MIB, SrcReg, ARM::gsub_0, getKillRegState(isKill), TRI);
+                AddDReg(MIB, SrcReg, ARM::gsub_1, 0, TRI);
       } else
         llvm_unreachable("Unknown reg class!");
       break;
@@ -938,6 +947,7 @@ loadRegFromStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
   DebugLoc DL;
   if (I != MBB.end()) DL = I->getDebugLoc();
   MachineFunction &MF = *MBB.getParent();
+  ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
   MachineFrameInfo &MFI = *MF.getFrameInfo();
   unsigned Align = MFI.getObjectAlignment(FI);
   MachineMemOperand *MMO =
@@ -963,6 +973,15 @@ loadRegFromStackSlot(MachineBasicBlock &MBB, MachineBasicBlock::iterator I,
     if (ARM::DPRRegClass.hasSubClassEq(RC)) {
       AddDefaultPred(BuildMI(MBB, I, DL, get(ARM::VLDRD), DestReg)
                    .addFrameIndex(FI).addImm(0).addMemOperand(MMO));
+    } else if (ARM::GPRPairRegClass.hasSubClassEq(RC)) {
+      unsigned LdmOpc = AFI->isThumbFunction() ? ARM::t2LDMIA : ARM::LDMIA;
+      MachineInstrBuilder MIB =
+        AddDefaultPred(BuildMI(MBB, I, DL, get(LdmOpc))
+                    .addFrameIndex(FI).addImm(0).addMemOperand(MMO));
+      MIB = AddDReg(MIB, DestReg, ARM::gsub_0, RegState::DefineNoRead, TRI);
+      MIB = AddDReg(MIB, DestReg, ARM::gsub_1, RegState::DefineNoRead, TRI);
+      if (TargetRegisterInfo::isPhysicalRegister(DestReg))
+        MIB.addReg(DestReg, RegState::ImplicitDefine);
     } else
       llvm_unreachable("Unknown reg class!");
     break;
diff --git a/lib/Target/ARM/ARMBaseRegisterInfo.cpp b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
index 68e7ce53c6..d3585bbd46 100644
--- a/lib/Target/ARM/ARMBaseRegisterInfo.cpp
+++ b/lib/Target/ARM/ARMBaseRegisterInfo.cpp
@@ -106,12 +106,23 @@ getReservedRegs(const MachineFunction &MF) const {
     for (unsigned i = 0; i != 16; ++i)
       Reserved.set(ARM::D16 + i);
   }
+  const TargetRegisterClass *RC  = &ARM::GPRPairRegClass;
+  for(TargetRegisterClass::iterator I = RC->begin(), E = RC->end(); I!=E; ++I)
+    for (MCSubRegIterator SI(*I, this); SI.isValid(); ++SI)
+      if (Reserved.test(*SI)) Reserved.set(*I);
+
   return Reserved;
 }
 
 bool ARMBaseRegisterInfo::isReservedReg(const MachineFunction &MF,
                                         unsigned Reg) const {
   const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
+  const TargetRegisterClass *RC  = &ARM::GPRPairRegClass;
+  if (RC->contains(Reg)) {
+    for (MCSubRegIterator SI(Reg, this); SI.isValid(); ++SI)
+      if(isReservedReg(MF, *SI)) return true;
+    return false;
+  }
 
   switch (Reg) {
   default: break;
@@ -147,6 +158,7 @@ ARMBaseRegisterInfo::getLargestLegalSuperClass(const TargetRegisterClass *RC)
     case ARM::QPRRegClassID:
     case ARM::QQPRRegClassID:
     case ARM::QQQQPRRegClassID:
+    case ARM::GPRPairRegClassID:
       return Super;
     }
     Super = *I++;
diff --git a/lib/Target/ARM/ARMRegisterInfo.td b/lib/Target/ARM/ARMRegisterInfo.td
index ed8ac1aff7..b0f576bc2b 100644
--- a/lib/Target/ARM/ARMRegisterInfo.td
+++ b/lib/Target/ARM/ARMRegisterInfo.td
@@ -49,6 +49,9 @@ def ssub_0  : SubRegIndex;
 def ssub_1  : SubRegIndex;
 def ssub_2  : SubRegIndex<[dsub_1, ssub_0]>;
 def ssub_3  : SubRegIndex<[dsub_1, ssub_1]>;
+
+def gsub_0  : SubRegIndex;
+def gsub_1  : SubRegIndex;
 // Let TableGen synthesize the remaining 12 ssub_* indices.
 // We don't need to name them.
 }
@@ -313,6 +316,17 @@ def DPair : RegisterClass<"ARM", [v16i8, v8i16, v4i32, v2i64, v4f32, v2f64],
   let AltOrderSelect = [{ return 1; }];
 }
 
+// Pseudo-registers representing even-odd pairs of GPRs from R1 to R13/SP.
+// These are needed by instructions (e.g. ldrexd/strexd) requiring even-odd GPRs.
+def Tuples2R : RegisterTuples<[gsub_0, gsub_1],
+                              [(add R0, R2, R4, R6, R8, R10, R12),
+                               (add R1, R3, R5, R7, R9, R11, SP)]>;
+
+// Register class representing a pair of even-odd GPRs.
+def GPRPair : RegisterClass<"ARM", [untyped], 64, (add Tuples2R)> {
+  let Size = 64; // 2 x 32 bits, we have no predefined type of that size.
+}
+
 // Pseudo-registers representing 3 consecutive D registers.
 def Tuples3D : RegisterTuples<[dsub_0, dsub_1, dsub_2],
                               [(shl DPR, 0),