[PowerPC] Fix small argument stack slot offset for LE

When small arguments (structures < 8 bytes or "float") are passed in a
stack slot in the ppc64 SVR4 ABI, they must reside in the least
significant part of that slot.  On BE, this means that an offset needs
to be added to the stack address of the parameter, but on LE, the least
significant part of the slot has the same address as the slot itself.

This changes the PowerPC back-end ABI code to only add the small
argument stack slot offset for BE.  It also adds test cases to verify
the correct behavior on both BE and LE.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211368 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 20 insertions, 11 deletions

diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp
index f6884d5a27..b20516e3a4 100644
--- a/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -2433,6 +2433,7 @@ PPCTargetLowering::LowerFormalArguments_64SVR4(
                                       SmallVectorImpl<SDValue> &InVals) const {
   // TODO: add description of PPC stack frame format, or at least some docs.
   //
+  bool isLittleEndian = Subtarget.isLittleEndian();
   MachineFunction &MF = DAG.getMachineFunction();
   MachineFrameInfo *MFI = MF.getFrameInfo();
   PPCFunctionInfo *FuncInfo = MF.getInfo<PPCFunctionInfo>();
@@ -2533,7 +2534,7 @@ PPCTargetLowering::LowerFormalArguments_64SVR4(
       }
 
       // All aggregates smaller than 8 bytes must be passed right-justified.
-      if (ObjSize < PtrByteSize)
+      if (ObjSize < PtrByteSize && !isLittleEndian)
         CurArgOffset = CurArgOffset + (PtrByteSize - ObjSize);
       // The value of the object is its address.
       int FI = MFI->CreateFixedObject(ObjSize, CurArgOffset, true);
@@ -2683,9 +2684,9 @@ PPCTargetLowering::LowerFormalArguments_64SVR4(
     // We need to load the argument to a virtual register if we determined
     // above that we ran out of physical registers of the appropriate type.
     if (needsLoad) {
-      int FI = MFI->CreateFixedObject(ObjSize,
-                                      CurArgOffset + (ArgSize - ObjSize),
-                                      isImmutable);
+      if (ObjSize < ArgSize && !isLittleEndian)
+        CurArgOffset += ArgSize - ObjSize;
+      int FI = MFI->CreateFixedObject(ObjSize, CurArgOffset, isImmutable);
       SDValue FIN = DAG.getFrameIndex(FI, PtrVT);
       ArgVal = DAG.getLoad(ObjectVT, dl, Chain, FIN, MachinePointerInfo(),
                            false, false, false, 0);
@@ -4034,6 +4035,7 @@ PPCTargetLowering::LowerCall_64SVR4(SDValue Chain, SDValue Callee,
                                     SDLoc dl, SelectionDAG &DAG,
                                     SmallVectorImpl<SDValue> &InVals) const {
 
+  bool isLittleEndian = Subtarget.isLittleEndian();
   unsigned NumOps = Outs.size();
 
   EVT PtrVT = DAG.getTargetLoweringInfo().getPointerTy();
@@ -4177,9 +4179,12 @@ PPCTargetLowering::LowerCall_64SVR4(SDValue Chain, SDValue Callee,
       }
 
       if (GPR_idx == NumGPRs && Size < 8) {
-        SDValue Const = DAG.getConstant(PtrByteSize - Size,
-                                        PtrOff.getValueType());
-        SDValue AddPtr = DAG.getNode(ISD::ADD, dl, PtrVT, PtrOff, Const);
+        SDValue AddPtr = PtrOff;
+        if (!isLittleEndian) {
+          SDValue Const = DAG.getConstant(PtrByteSize - Size,
+                                          PtrOff.getValueType());
+          AddPtr = DAG.getNode(ISD::ADD, dl, PtrVT, PtrOff, Const);
+        }
         Chain = CallSeqStart = createMemcpyOutsideCallSeq(Arg, AddPtr,
                                                           CallSeqStart,
                                                           Flags, DAG, dl);
@@ -4214,8 +4219,11 @@ PPCTargetLowering::LowerCall_64SVR4(SDValue Chain, SDValue Callee,
         // small aggregates, particularly for packed ones.
         // FIXME: It would be preferable to use the slot in the
         // parameter save area instead of a new local variable.
-        SDValue Const = DAG.getConstant(8 - Size, PtrOff.getValueType());
-        SDValue AddPtr = DAG.getNode(ISD::ADD, dl, PtrVT, PtrOff, Const);
+        SDValue AddPtr = PtrOff;
+        if (!isLittleEndian) {
+          SDValue Const = DAG.getConstant(8 - Size, PtrOff.getValueType());
+          AddPtr = DAG.getNode(ISD::ADD, dl, PtrVT, PtrOff, Const);
+        }
         Chain = CallSeqStart = createMemcpyOutsideCallSeq(Arg, AddPtr,
                                                           CallSeqStart,
                                                           Flags, DAG, dl);
@@ -4276,7 +4284,8 @@ PPCTargetLowering::LowerCall_64SVR4(SDValue Chain, SDValue Callee,
           // must be passed right-justified in the stack doubleword, and
           // in the GPR, if one is available.
           SDValue StoreOff;
-          if (Arg.getSimpleValueType().SimpleTy == MVT::f32) {
+          if (Arg.getSimpleValueType().SimpleTy == MVT::f32 &&
+              !isLittleEndian) {
             SDValue ConstFour = DAG.getConstant(4, PtrOff.getValueType());
             StoreOff = DAG.getNode(ISD::ADD, dl, PtrVT, PtrOff, ConstFour);
           } else
@@ -4300,7 +4309,7 @@ PPCTargetLowering::LowerCall_64SVR4(SDValue Chain, SDValue Callee,
       } else {
         // Single-precision floating-point values are mapped to the
         // second (rightmost) word of the stack doubleword.
-        if (Arg.getValueType() == MVT::f32) {
+        if (Arg.getValueType() == MVT::f32 && !isLittleEndian) {
           SDValue ConstFour = DAG.getConstant(4, PtrOff.getValueType());
           PtrOff = DAG.getNode(ISD::ADD, dl, PtrVT, PtrOff, ConstFour);
         }