R600/SI: add folding helper

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Tom Stellard <thomas.stellard@amd.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176100 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 30 insertions, 0 deletions

diff --git a/lib/Target/R600/AMDGPUISelLowering.h b/lib/Target/R600/AMDGPUISelLowering.h
index 404f620..9e7d997 100644
--- a/lib/Target/R600/AMDGPUISelLowering.h
+++ b/lib/Target/R600/AMDGPUISelLowering.h
@@ -65,6 +65,10 @@ public:
   SDValue LowerMinMax(SDValue Op, SelectionDAG &DAG) const;
   virtual const char* getTargetNodeName(unsigned Opcode) const;
 
+  virtual SDNode *PostISelFolding(MachineSDNode *N, SelectionDAG &DAG) const {
+    return N;
+  }
+
 // Functions defined in AMDILISelLowering.cpp
 public:
 
diff --git a/lib/Target/R600/AMDILISelDAGToDAG.cpp b/lib/Target/R600/AMDILISelDAGToDAG.cpp
index 2e726e9..2f70fa9 100644
--- a/lib/Target/R600/AMDILISelDAGToDAG.cpp
+++ b/lib/Target/R600/AMDILISelDAGToDAG.cpp
@@ -43,6 +43,7 @@ public:
 
   SDNode *Select(SDNode *N);
   virtual const char *getPassName() const;
+  virtual void PostprocessISelDAG();
 
 private:
   inline SDValue getSmallIPtrImm(unsigned Imm);
@@ -575,3 +576,21 @@ bool AMDGPUDAGToDAGISel::SelectADDRIndirect(SDValue Addr, SDValue &Base,
 
   return true;
 }
+
+void AMDGPUDAGToDAGISel::PostprocessISelDAG() {
+
+  // Go over all selected nodes and try to fold them a bit more
+  const AMDGPUTargetLowering& Lowering = ((const AMDGPUTargetLowering&)TLI);
+  for (SelectionDAG::allnodes_iterator I = CurDAG->allnodes_begin(),
+       E = CurDAG->allnodes_end(); I != E; ++I) {
+
+    MachineSDNode *Node = dyn_cast<MachineSDNode>(I);
+    if (!Node)
+      continue;
+
+    SDNode *ResNode = Lowering.PostISelFolding(Node, *CurDAG);
+    if (ResNode != Node)
+      ReplaceUses(Node, ResNode);
+  }
+}
+
diff --git a/lib/Target/R600/SIISelLowering.cpp b/lib/Target/R600/SIISelLowering.cpp
index 212e3f2..13173e8 100644
--- a/lib/Target/R600/SIISelLowering.cpp
+++ b/lib/Target/R600/SIISelLowering.cpp
@@ -357,3 +357,9 @@ SDValue SITargetLowering::PerformDAGCombine(SDNode *N,
   }
   return SDValue();
 }
+
+SDNode *SITargetLowering::PostISelFolding(MachineSDNode *Node,
+                                          SelectionDAG &DAG) const {
+  // TODO: Implement immediate folding
+  return Node;
+}
diff --git a/lib/Target/R600/SIISelLowering.h b/lib/Target/R600/SIISelLowering.h
index 5d048f8..71f99ac 100644
--- a/lib/Target/R600/SIISelLowering.h
+++ b/lib/Target/R600/SIISelLowering.h
@@ -41,6 +41,7 @@ public:
   virtual EVT getSetCCResultType(EVT VT) const;
   virtual SDValue LowerOperation(SDValue Op, SelectionDAG &DAG) const;
   virtual SDValue PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const;
+  virtual SDNode *PostISelFolding(MachineSDNode *N, SelectionDAG &DAG) const;
 };
 
 } // End namespace llvm