1 files changed, 71 insertions, 2 deletions
diff --git a/llvm/lib/Target/X86/X86CallLowering.cpp b/llvm/lib/Target/X86/X86CallLowering.cpp
index 5ae4962378d..b648b90666e 100644
--- a/llvm/lib/Target/X86/X86CallLowering.cpp
+++ b/llvm/lib/Target/X86/X86CallLowering.cpp
@@ -16,10 +16,18 @@
 #include "X86CallLowering.h"
 #include "X86ISelLowering.h"
 #include "X86InstrInfo.h"
+#include "X86TargetMachine.h"
+#include "X86CallingConv.h"
+
 #include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
+#include "llvm/CodeGen/MachineValueType.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
 
 using namespace llvm;
 
+#include "X86GenCallingConv.inc"
+
 #ifndef LLVM_BUILD_GLOBAL_ISEL
 #error "This shouldn't be built without GISel"
 #endif
@@ -33,14 +41,75 @@ bool X86CallLowering::lowerReturn(MachineIRBuilder &MIRBuilder,
   if (Val)
     return false;
 
+  // silence unused-function warning, remove after the function implementation.
+  (void)RetCC_X86;
+
   MIRBuilder.buildInstr(X86::RET).addImm(0);
 
   return true;
 }
 
+namespace {
+struct FormalArgHandler : public CallLowering::ValueHandler {
+  FormalArgHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
+                   CCAssignFn *AssignFn, const DataLayout &DL)
+      : ValueHandler(MIRBuilder, MRI, AssignFn), DL(DL) {}
+
+  unsigned getStackAddress(uint64_t Size, int64_t Offset,
+                           MachinePointerInfo &MPO) override {
+
+    auto &MFI = MIRBuilder.getMF().getFrameInfo();
+    int FI = MFI.CreateFixedObject(Size, Offset, true);
+    MPO = MachinePointerInfo::getFixedStack(MIRBuilder.getMF(), FI);
+
+    unsigned AddrReg =
+        MRI.createGenericVirtualRegister(LLT::pointer(0,
+                                         DL.getPointerSizeInBits(0)));
+    MIRBuilder.buildFrameIndex(AddrReg, FI);
+    return AddrReg;
+  }
+
+  void assignValueToAddress(unsigned ValVReg, unsigned Addr, uint64_t Size,
+                            MachinePointerInfo &MPO, CCValAssign &VA) override {
+
+    auto MMO = MIRBuilder.getMF().getMachineMemOperand(
+        MPO, MachineMemOperand::MOLoad | MachineMemOperand::MOInvariant, Size,
+        0);
+    MIRBuilder.buildLoad(ValVReg, Addr, *MMO);
+  }
+
+  void assignValueToReg(unsigned ValVReg, unsigned PhysReg,
+                        CCValAssign &VA) override {
+    MIRBuilder.getMBB().addLiveIn(PhysReg);
+    MIRBuilder.buildCopy(ValVReg, PhysReg);
+  }
+
+  const DataLayout &DL;
+};
+}
+
 bool X86CallLowering::lowerFormalArguments(MachineIRBuilder &MIRBuilder,
                                            const Function &F,
                                            ArrayRef<unsigned> VRegs) const {
-  // TODO: handle functions with one or more arguments.
-  return F.arg_empty();
+  if (F.arg_empty())
+    return true;
+
+  //TODO: handle variadic function
+  if (F.isVarArg())
+    return false;
+
+  auto DL = MIRBuilder.getMF().getDataLayout();
+
+  SmallVector<ArgInfo, 8> ArgInfos;
+  unsigned Idx = 0;
+  for (auto &Arg : F.getArgumentList()) {
+    ArgInfo AInfo(VRegs[Idx], Arg.getType());
+    setArgFlags(AInfo, Idx + 1, DL, F);
+    ArgInfos.push_back(AInfo);
+    Idx++;
+  }
+
+  FormalArgHandler ArgHandler(MIRBuilder, MIRBuilder.getMF().getRegInfo(),
+                              CC_X86, DL);
+  return handleAssignments(MIRBuilder, ArgInfos, ArgHandler);
 }