4 files changed, 137 insertions, 1 deletions

diff --git a/llvm/lib/Target/R600/SIISelLowering.cpp b/llvm/lib/Target/R600/SIISelLowering.cpp
index 911c5e55949..6d2e9575e59 100644
--- a/llvm/lib/Target/R600/SIISelLowering.cpp
+++ b/llvm/lib/Target/R600/SIISelLowering.cpp
@@ -235,6 +235,26 @@ SITargetLowering::SITargetLowering(TargetMachine &TM) :
 
   setTargetDAGCombine(ISD::UINT_TO_FP);
 
+  // All memory operations. Some folding on the pointer operand is done to help
+  // matching the constant offsets in the addressing modes.
+  setTargetDAGCombine(ISD::LOAD);
+  setTargetDAGCombine(ISD::STORE);
+  setTargetDAGCombine(ISD::ATOMIC_LOAD);
+  setTargetDAGCombine(ISD::ATOMIC_STORE);
+  setTargetDAGCombine(ISD::ATOMIC_CMP_SWAP);
+  setTargetDAGCombine(ISD::ATOMIC_CMP_SWAP_WITH_SUCCESS);
+  setTargetDAGCombine(ISD::ATOMIC_SWAP);
+  setTargetDAGCombine(ISD::ATOMIC_LOAD_ADD);
+  setTargetDAGCombine(ISD::ATOMIC_LOAD_SUB);
+  setTargetDAGCombine(ISD::ATOMIC_LOAD_AND);
+  setTargetDAGCombine(ISD::ATOMIC_LOAD_OR);
+  setTargetDAGCombine(ISD::ATOMIC_LOAD_XOR);
+  setTargetDAGCombine(ISD::ATOMIC_LOAD_NAND);
+  setTargetDAGCombine(ISD::ATOMIC_LOAD_MIN);
+  setTargetDAGCombine(ISD::ATOMIC_LOAD_MAX);
+  setTargetDAGCombine(ISD::ATOMIC_LOAD_UMIN);
+  setTargetDAGCombine(ISD::ATOMIC_LOAD_UMAX);
+
   setSchedulingPreference(Sched::RegPressure);
 }
 
@@ -1296,6 +1316,56 @@ SDValue SITargetLowering::performUCharToFloatCombine(SDNode *N,
   return SDValue();
 }
 
+// (shl (add x, c1), c2) -> add (shl x, c2), (shl c1, c2)
+
+// This is a variant of
+// (mul (add x, c1), c2) -> add (mul x, c2), (mul c1, c2),
+//
+// The normal DAG combiner will do this, but only if the add has one use since
+// that would increase the number of instructions.
+//
+// This prevents us from seeing a constant offset that can be folded into a
+// memory instruction's addressing mode. If we know the resulting add offset of
+// a pointer can be folded into an addressing offset, we can replace the pointer
+// operand with the add of new constant offset. This eliminates one of the uses,
+// and may allow the remaining use to also be simplified.
+//
+SDValue SITargetLowering::performSHLPtrCombine(SDNode *N,
+                                               unsigned AddrSpace,
+                                               DAGCombinerInfo &DCI) const {
+  SDValue N0 = N->getOperand(0);
+  SDValue N1 = N->getOperand(1);
+
+  if (N0.getOpcode() != ISD::ADD)
+    return SDValue();
+
+  const ConstantSDNode *CN1 = dyn_cast<ConstantSDNode>(N1);
+  if (!CN1)
+    return SDValue();
+
+  const ConstantSDNode *CAdd = dyn_cast<ConstantSDNode>(N0.getOperand(1));
+  if (!CAdd)
+    return SDValue();
+
+  const SIInstrInfo *TII = static_cast<const SIInstrInfo *>(
+      getTargetMachine().getSubtargetImpl()->getInstrInfo());
+
+  // If the resulting offset is too large, we can't fold it into the addressing
+  // mode offset.
+  APInt Offset = CAdd->getAPIntValue() << CN1->getAPIntValue();
+  if (!TII->canFoldOffset(Offset.getZExtValue(), AddrSpace))
+    return SDValue();
+
+  SelectionDAG &DAG = DCI.DAG;
+  SDLoc SL(N);
+  EVT VT = N->getValueType(0);
+
+  SDValue ShlX = DAG.getNode(ISD::SHL, SL, VT, N0.getOperand(0), N1);
+  SDValue COffset = DAG.getConstant(Offset, MVT::i32);
+
+  return DAG.getNode(ISD::ADD, SL, VT, ShlX, COffset);
+}
+
 SDValue SITargetLowering::PerformDAGCombine(SDNode *N,
                                             DAGCombinerInfo &DCI) const {
   SelectionDAG &DAG = DCI.DAG;
@@ -1348,8 +1418,45 @@ SDValue SITargetLowering::PerformDAGCombine(SDNode *N,
   case ISD::UINT_TO_FP: {
     return performUCharToFloatCombine(N, DCI);
   }
-  }
+  case ISD::LOAD:
+  case ISD::STORE:
+  case ISD::ATOMIC_LOAD:
+  case ISD::ATOMIC_STORE:
+  case ISD::ATOMIC_CMP_SWAP:
+  case ISD::ATOMIC_CMP_SWAP_WITH_SUCCESS:
+  case ISD::ATOMIC_SWAP:
+  case ISD::ATOMIC_LOAD_ADD:
+  case ISD::ATOMIC_LOAD_SUB:
+  case ISD::ATOMIC_LOAD_AND:
+  case ISD::ATOMIC_LOAD_OR:
+  case ISD::ATOMIC_LOAD_XOR:
+  case ISD::ATOMIC_LOAD_NAND:
+  case ISD::ATOMIC_LOAD_MIN:
+  case ISD::ATOMIC_LOAD_MAX:
+  case ISD::ATOMIC_LOAD_UMIN:
+  case ISD::ATOMIC_LOAD_UMAX: { // TODO: Target mem intrinsics.
+    if (DCI.isBeforeLegalize())
+      break;
+
+    MemSDNode *MemNode = cast<MemSDNode>(N);
+    SDValue Ptr = MemNode->getBasePtr();
 
+    // TODO: We could also do this for multiplies.
+    unsigned AS = MemNode->getAddressSpace();
+    if (Ptr.getOpcode() == ISD::SHL && AS != AMDGPUAS::PRIVATE_ADDRESS) {
+      SDValue NewPtr = performSHLPtrCombine(Ptr.getNode(), AS, DCI);
+      if (NewPtr) {
+        SmallVector<SDValue, 8> NewOps;
+        for (unsigned I = 0, N = MemNode->getNumOperands(); I != N; ++I)
+          NewOps.push_back(MemNode->getOperand(I));
+
+        NewOps[N->getOpcode() == ISD::STORE ? 2 : 1] = NewPtr;
+        return SDValue(DAG.UpdateNodeOperands(MemNode, NewOps), 0);
+      }
+    }
+    break;
+  }
+  }
   return AMDGPUTargetLowering::PerformDAGCombine(N, DCI);
 }
 
diff --git a/llvm/lib/Target/R600/SIISelLowering.h b/llvm/lib/Target/R600/SIISelLowering.h
index 2a9aa49491f..b952bc0345a 100644
--- a/llvm/lib/Target/R600/SIISelLowering.h
+++ b/llvm/lib/Target/R600/SIISelLowering.h
@@ -56,6 +56,9 @@ class SITargetLowering : public AMDGPUTargetLowering {
 
   static SDValue performUCharToFloatCombine(SDNode *N,
                                             DAGCombinerInfo &DCI);
+  SDValue performSHLPtrCombine(SDNode *N,
+                               unsigned AS,
+                               DAGCombinerInfo &DCI) const;
 
 public:
   SITargetLowering(TargetMachine &tm);
diff --git a/llvm/lib/Target/R600/SIInstrInfo.cpp b/llvm/lib/Target/R600/SIInstrInfo.cpp
index 5cd8ddfaceb..3868f63b3a8 100644
--- a/llvm/lib/Target/R600/SIInstrInfo.cpp
+++ b/llvm/lib/Target/R600/SIInstrInfo.cpp
@@ -803,6 +803,28 @@ bool SIInstrInfo::isImmOperandLegal(const MachineInstr *MI, unsigned OpNo,
   return RI.regClassCanUseImmediate(OpInfo.RegClass);
 }
 
+bool SIInstrInfo::canFoldOffset(unsigned OffsetSize, unsigned AS) {
+  switch (AS) {
+  case AMDGPUAS::GLOBAL_ADDRESS: {
+    // MUBUF instructions a 12-bit offset in bytes.
+    return isUInt<12>(OffsetSize);
+  }
+  case AMDGPUAS::CONSTANT_ADDRESS: {
+    // SMRD instructions have an 8-bit offset in dwords.
+    return (OffsetSize % 4 == 0) && isUInt<8>(OffsetSize / 4);
+  }
+  case AMDGPUAS::LOCAL_ADDRESS:
+  case AMDGPUAS::REGION_ADDRESS: {
+    // The single offset versions have a 16-bit offset in bytes.
+    return isUInt<16>(OffsetSize);
+  }
+  case AMDGPUAS::PRIVATE_ADDRESS:
+    // Indirect register addressing does not use any offsets.
+  default:
+    return 0;
+  }
+}
+
 bool SIInstrInfo::hasVALU32BitEncoding(unsigned Opcode) const {
   return AMDGPU::getVOPe32(Opcode) != -1;
 }
diff --git a/llvm/lib/Target/R600/SIInstrInfo.h b/llvm/lib/Target/R600/SIInstrInfo.h
index 9d16bc4327b..cab448ac9f5 100644
--- a/llvm/lib/Target/R600/SIInstrInfo.h
+++ b/llvm/lib/Target/R600/SIInstrInfo.h
@@ -119,6 +119,10 @@ public:
   bool isImmOperandLegal(const MachineInstr *MI, unsigned OpNo,
                          const MachineOperand &MO) const;
 
+  /// \brief Return true if the given offset Size in bytes can be folded into
+  /// the immediate offsets of a memory instruction for the given address space.
+  static bool canFoldOffset(unsigned OffsetSize, unsigned AS) LLVM_READNONE;
+
   /// \brief Return true if this 64-bit VALU instruction has a 32-bit encoding.
   /// This function will return false if you pass it a 32-bit instruction.
   bool hasVALU32BitEncoding(unsigned Opcode) const;