Add the ability to lower return instructions to TargetLowering. This

allows us to lower legal return types to something else, to meet ABI
requirements (such as that i64 be returned in two i32 regs on Darwin/ppc).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23802 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Target/TargetLowering.h b/include/llvm/Target/TargetLowering.h
index 734c8dc0297cd1af1ee3fdf8b0e7be2befda2e89..02278e9e422304ab9af6f6f1d15af7c0e7ccd419 100644 (file)
--- a/include/llvm/Target/TargetLowering.h
+++ b/include/llvm/Target/TargetLowering.h
@@ -311,6 +311,12 @@ public:
               unsigned CallingConv, bool isTailCall, SDOperand Callee,
               ArgListTy &Args, SelectionDAG &DAG) = 0;
 
+  /// LowerReturnTo - This hook lowers a return instruction into the appropriate
+  /// legal ISD::RET node for the target's current ABI.  This method is optional
+  /// and is intended for targets that need non-standard behavior.
+  virtual SDOperand LowerReturnTo(SDOperand Chain, SDOperand Op, 
+                                  SelectionDAG &DAG);
+  
   /// LowerVAStart - This lowers the llvm.va_start intrinsic.  If not
   /// implemented, this method prints a message and aborts.  This method should
   /// return the modified chain value.  Note that VAListPtr* correspond to the

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 72ee7501082c499999cbb69b4772556fb82faf51..4a89578eaa03538b389f39a6ebbb0857951f39b6 100644 (file)
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -450,8 +450,8 @@ void SelectionDAGLowering::visitRet(ReturnInst &I) {
   case MVT::f64:
     break; // No extension needed!
   }
-
-  DAG.setRoot(DAG.getNode(ISD::RET, MVT::Other, getRoot(), Op1));
+  // Allow targets to lower this further to meet ABI requirements
+  DAG.setRoot(TLI.LowerReturnTo(getRoot(), Op1, DAG));
 }
 
 void SelectionDAGLowering::visitBr(BranchInst &I) {
@@ -898,6 +898,11 @@ MachineBasicBlock *TargetLowering::InsertAtEndOfBasicBlock(MachineInstr *MI,
   return 0;  
 }
 
+SDOperand TargetLowering::LowerReturnTo(SDOperand Chain, SDOperand Op,
+                                        SelectionDAG &DAG) {
+  return DAG.getNode(ISD::RET, MVT::Other, Chain, Op);
+}
+
 SDOperand TargetLowering::LowerVAStart(SDOperand Chain,
                                        SDOperand VAListP, Value *VAListV,
                                        SelectionDAG &DAG) {

diff --git a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index c55bd30a2dd18469a113d6f0b2c49875708e677c..754809303112fc6be9f22accbd8a7424c884b826 100644 (file)
--- a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -1206,6 +1206,22 @@ SDOperand PPCDAGToDAGISel::Select(SDOperand Op) {
       
     // Other cases are autogenerated.
     break;
+  case ISD::ANY_EXTEND:
+    switch(N->getValueType(0)) {
+    default: assert(0 && "Unhandled type in ANY_EXTEND");
+    case MVT::i64:
+      CurDAG->SelectNodeTo(N, PPC::OR8, MVT::i64, Select(N->getOperand(0)), 
+                           Select(N->getOperand(0)));
+      break;
+    }
+    return SDOperand(N, 0);
+  case ISD::ZERO_EXTEND:
+    assert(N->getValueType(0) == MVT::i64 && 
+           N->getOperand(0).getValueType() == MVT::i32 &&
+           "ZERO_EXTEND only supported for i32 -> i64");
+    CurDAG->SelectNodeTo(N, PPC::RLDICL, MVT::i64, Select(N->getOperand(0)),
+                         getI32Imm(32));
+    return SDOperand(N, 0);
   case ISD::SHL: {
     unsigned Imm, SH, MB, ME;
     if (isOpcWithIntImmediate(N->getOperand(0).Val, ISD::AND, Imm) &&
@@ -1393,11 +1409,6 @@ SDOperand PPCDAGToDAGISel::Select(SDOperand Op) {
       SDOperand Val = Select(N->getOperand(1));
       if (N->getOperand(1).getValueType() == MVT::i32) {
         Chain = CurDAG->getCopyToReg(Chain, PPC::R3, Val);
-      } else if (N->getOperand(1).getValueType() == MVT::i64) {
-        SDOperand Srl = CurDAG->getTargetNode(PPC::RLDICL, MVT::i64, Val,
-                                              getI32Imm(32), getI32Imm(32));
-        Chain = CurDAG->getCopyToReg(Chain, PPC::R4, Val);
-        Chain = CurDAG->getCopyToReg(Chain, PPC::R3, Srl);
       } else {
         assert(MVT::isFloatingPoint(N->getOperand(1).getValueType()));
         Chain = CurDAG->getCopyToReg(Chain, PPC::F1, Val);

diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp
index 8cc538df83afab6eaf94604ec4d7b62e98f14bf7..5256e4839d1a14e3ce90d7cf951581bd7dad9598 100644 (file)
--- a/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -693,6 +693,19 @@ PPCTargetLowering::LowerCallTo(SDOperand Chain,
   return std::make_pair(RetVal, Chain);
 }
 
+SDOperand PPCTargetLowering::LowerReturnTo(SDOperand Chain, SDOperand Op,
+                                           SelectionDAG &DAG) {
+  if (Op.getValueType() == MVT::i64) {
+    SDOperand Hi = DAG.getNode(ISD::EXTRACT_ELEMENT, MVT::i32, Op, 
+                               DAG.getConstant(1, MVT::i32));
+    SDOperand Lo = DAG.getNode(ISD::EXTRACT_ELEMENT, MVT::i32, Op,
+                               DAG.getConstant(0, MVT::i32));
+    return DAG.getNode(ISD::RET, MVT::Other, Chain, Lo, Hi);
+  } else {
+    return DAG.getNode(ISD::RET, MVT::Other, Chain, Op);
+  }
+}
+
 SDOperand PPCTargetLowering::LowerVAStart(SDOperand Chain, SDOperand VAListP,
                                           Value *VAListV, SelectionDAG &DAG) {
   // vastart just stores the address of the VarArgsFrameIndex slot into the

diff --git a/lib/Target/PowerPC/PPCISelLowering.h b/lib/Target/PowerPC/PPCISelLowering.h
index 0b3690ddf691c8c58540e1e5e5be0a2a023efb18..f44f192e6934855dbd5c438093734238b6299794 100644 (file)
--- a/lib/Target/PowerPC/PPCISelLowering.h
+++ b/lib/Target/PowerPC/PPCISelLowering.h
@@ -63,6 +63,9 @@ namespace llvm {
                   unsigned CC,
                   bool isTailCall, SDOperand Callee, ArgListTy &Args,
                   SelectionDAG &DAG);
+
+    virtual SDOperand LowerReturnTo(SDOperand Chain, SDOperand Op,
+                                    SelectionDAG &DAG);
     
     virtual SDOperand LowerVAStart(SDOperand Chain, SDOperand VAListP,
                                    Value *VAListV, SelectionDAG &DAG);