[PATCH 3/5] R600: Convert non global value const loads to global loads

[Jan Vesely]

This seems more complicated, but const laods are getting their own instructions
in the next commit

Signed-off-by: Jan Vesely <jan.vesely at rutgers.edu>
---
 lib/Target/R600/AMDGPUISelDAGToDAG.cpp |  4 ++--
 lib/Target/R600/R600ISelLowering.cpp   | 35 ++++++++++++++++++++++++----------
 2 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/lib/Target/R600/AMDGPUISelDAGToDAG.cpp b/lib/Target/R600/AMDGPUISelDAGToDAG.cpp
index df4461e..bba753f 100644
--- a/lib/Target/R600/AMDGPUISelDAGToDAG.cpp
+++ b/lib/Target/R600/AMDGPUISelDAGToDAG.cpp
@@ -649,9 +649,9 @@ bool AMDGPUDAGToDAGISel::isConstantLoad(const LoadSDNode *N, int CbId) const {
 }
 
 bool AMDGPUDAGToDAGISel::isGlobalLoad(const LoadSDNode *N) const {
+  //TODO: Why do we need this?
   if (N->getAddressSpace() == AMDGPUAS::CONSTANT_ADDRESS)
-    if (Subtarget->getGeneration() < AMDGPUSubtarget::SOUTHERN_ISLANDS ||
-        N->getMemoryVT().bitsLT(MVT::i32))
+    if (N->getMemoryVT().bitsLT(MVT::i32))
       return true;
 
   return checkType(N->getMemOperand()->getValue(), AMDGPUAS::GLOBAL_ADDRESS);
diff --git a/lib/Target/R600/R600ISelLowering.cpp b/lib/Target/R600/R600ISelLowering.cpp
index 8357b6d..33909bf 100644
--- a/lib/Target/R600/R600ISelLowering.cpp
+++ b/lib/Target/R600/R600ISelLowering.cpp
@@ -1469,18 +1469,33 @@ SDValue R600TargetLowering::LowerLOAD(SDValue Op, SelectionDAG &DAG) const
   }
 
   // Lower loads constant address space global variable loads
-  if (LoadNode->getAddressSpace() == AMDGPUAS::CONSTANT_ADDRESS &&
-      isa<GlobalVariable>(GetUnderlyingObject(
+  if ((LoadNode->getAddressSpace() == AMDGPUAS::CONSTANT_ADDRESS) &&
+      (LoadNode->getExtensionType() != ISD::SEXTLOAD)) {
+     if (isa<GlobalVariable>(GetUnderlyingObject(
           LoadNode->getMemOperand()->getValue(), *getDataLayout()))) {
 
-    SDValue Ptr = DAG.getZExtOrTrunc(LoadNode->getBasePtr(), DL,
-        getPointerTy(AMDGPUAS::PRIVATE_ADDRESS));
-    Ptr = DAG.getNode(ISD::SRL, DL, MVT::i32, Ptr,
-        DAG.getConstant(2, DL, MVT::i32));
-    return DAG.getNode(AMDGPUISD::REGISTER_LOAD, DL, Op->getVTList(),
-                       LoadNode->getChain(), Ptr,
-                       DAG.getTargetConstant(0, DL, MVT::i32),
-                       Op.getOperand(2));
+      SDValue Ptr = DAG.getZExtOrTrunc(LoadNode->getBasePtr(), DL,
+          getPointerTy(AMDGPUAS::PRIVATE_ADDRESS));
+      Ptr = DAG.getNode(ISD::SRL, DL, MVT::i32, Ptr,
+          DAG.getConstant(2, DL, MVT::i32));
+      return DAG.getNode(AMDGPUISD::REGISTER_LOAD, DL, Op->getVTList(),
+                         LoadNode->getChain(), Ptr,
+                         DAG.getTargetConstant(0, DL, MVT::i32),
+                         Op.getOperand(2));
+    } else {
+      /* Replace with global load from the same address */
+      EVT MemVT = LoadNode->getMemoryVT();
+      Type *InitTy = LoadNode->getMemOperand()->getValue()->getType();
+      PointerType *PtrTy = PointerType::get(InitTy, AMDGPUAS::GLOBAL_ADDRESS);
+      Ptr = DAG.getZExtOrTrunc(Ptr, DL, getPointerTy(AMDGPUAS::GLOBAL_ADDRESS));
+      return DAG.getExtLoad(LoadNode->getExtensionType(),
+                            DL, VT, Chain, Ptr,
+                            MachinePointerInfo(UndefValue::get(PtrTy)), MemVT,
+                            LoadNode->isVolatile(),
+                            LoadNode->isNonTemporal(),
+                            LoadNode->isInvariant(),
+                            LoadNode->getAlignment());
+    }
   }
 
   if (LoadNode->getAddressSpace() == AMDGPUAS::LOCAL_ADDRESS && VT.isVector()) {
-- 
2.1.0