[PowerPC] Fix lowering of byval parameters for sizes greater than 8 b…

…ytes.

To store a byval parameter the existing code would store as many 8 byte elements
as was required to store the full size of the byval parameter.
For example, a paramter of size 16 would store two element of 8 bytes.
A paramter of size 12 would also store two elements of 8 bytes.
This would sometimes store too many bytes as the size of the paramter is not
always a factor of 8.

This patch fixes that issue and now byval paramters are stored with the correct
number of bytes.

Reviewed By: nemanjai, #powerpc, quinnp, amyk

Differential Revision: https://reviews.llvm.org/D121430

llvm/lib/Target/PowerPC/PPCISelLowering.cpp

@@ -4431,8 +4431,11 @@ SDValue PPCTargetLowering::LowerFormalArguments_64SVR4(
           SDValue Off = DAG.getConstant(j, dl, PtrVT);
           Addr = DAG.getNode(ISD::ADD, dl, Off.getValueType(), Addr, Off);
         }
-        SDValue Store = DAG.getStore(Val.getValue(1), dl, Val, Addr,
-                                     MachinePointerInfo(&*FuncArg, j));
+        unsigned StoreSizeInBits = std::min(PtrByteSize, (ObjSize - j)) * 8;
+        EVT ObjType = EVT::getIntegerVT(*DAG.getContext(), StoreSizeInBits);
+        SDValue Store =
+            DAG.getTruncStore(Val.getValue(1), dl, Val, Addr,
+                              MachinePointerInfo(&*FuncArg, j), ObjType);
         MemOps.push_back(Store);
         ++GPR_idx;
       }
@@ -6269,8 +6272,11 @@ SDValue PPCTargetLowering::LowerCall_64SVR4(
         SDValue Const = DAG.getConstant(j, dl, PtrOff.getValueType());
         SDValue AddArg = DAG.getNode(ISD::ADD, dl, PtrVT, Arg, Const);
         if (GPR_idx != NumGPRs) {
-          SDValue Load =
-              DAG.getLoad(PtrVT, dl, Chain, AddArg, MachinePointerInfo());
+          unsigned LoadSizeInBits = std::min(PtrByteSize, (Size - j)) * 8;
+          EVT ObjType = EVT::getIntegerVT(*DAG.getContext(), LoadSizeInBits);
+          SDValue Load = DAG.getExtLoad(ISD::EXTLOAD, dl, PtrVT, Chain, AddArg,
+                                        MachinePointerInfo(), ObjType);
+
           MemOpChains.push_back(Load.getValue(1));
           RegsToPass.push_back(std::make_pair(GPR[GPR_idx++], Load));
           ArgOffset += PtrByteSize;

llvm/test/CodeGen/PowerPC/byval.ll

@@ -22,7 +22,7 @@ define dso_local i32 @bar() {
 ; CHECK-NEXT:    addi 3, 1, 40
 ; CHECK-NEXT:    bl foo
 ; CHECK-NEXT:    nop
-; CHECK-NEXT:    ld 7, 72(1)
+; CHECK-NEXT:    lwz 7, 72(1)
 ; CHECK-NEXT:    ld 6, 64(1)
 ; CHECK-NEXT:    ld 5, 56(1)
 ; CHECK-NEXT:    ld 4, 48(1)