[ARM] GlobalISel: Lower pointer args and returns

It is important to change the ArgInfo's type from pointer to integer, otherwise
the CC assign function won't know what to do. Instead of hacking it up, we use
ComputeValueVTs and introduce some of the helpers that we will need later on for
lowering more complex types.

llvm-svn: 293889

1 files changed, 29 insertions, 6 deletions

diff --git a/llvm/lib/Target/ARM/ARMCallLowering.cpp b/llvm/lib/Target/ARM/ARMCallLowering.cpp
index c5b49ef70fd..f37d6d7b1d0 100644
--- a/llvm/lib/Target/ARM/ARMCallLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMCallLowering.cpp
@@ -19,6 +19,7 @@
 #include "ARMISelLowering.h"
 #include "ARMSubtarget.h"
 
+#include "llvm/CodeGen/Analysis.h"
 #include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 
@@ -74,6 +75,25 @@ struct FuncReturnHandler : public CallLowering::ValueHandler {
 };
 } // End anonymous namespace.
 
+void ARMCallLowering::splitToValueTypes(const ArgInfo &OrigArg,
+                                        SmallVectorImpl<ArgInfo> &SplitArgs,
+                                        const DataLayout &DL,
+                                        MachineRegisterInfo &MRI) const {
+  const ARMTargetLowering &TLI = *getTLI<ARMTargetLowering>();
+  LLVMContext &Ctx = OrigArg.Ty->getContext();
+
+  SmallVector<EVT, 4> SplitVTs;
+  SmallVector<uint64_t, 4> Offsets;
+  ComputeValueVTs(TLI, DL, OrigArg.Ty, SplitVTs, &Offsets, 0);
+
+  assert(SplitVTs.size() == 1 && "Unsupported type");
+
+  // Even if there is no splitting to do, we still want to replace the original
+  // type (e.g. pointer type -> integer).
+  SplitArgs.emplace_back(OrigArg.Reg, SplitVTs[0].getTypeForEVT(Ctx),
+                         OrigArg.Flags, OrigArg.IsFixed);
+}
+
 /// Lower the return value for the already existing \p Ret. This assumes that
 /// \p MIRBuilder's insertion point is correct.
 bool ARMCallLowering::lowerReturnVal(MachineIRBuilder &MIRBuilder,
@@ -91,14 +111,16 @@ bool ARMCallLowering::lowerReturnVal(MachineIRBuilder &MIRBuilder,
   if (!isSupportedType(DL, TLI, Val->getType()))
     return false;
 
-  CCAssignFn *AssignFn =
-      TLI.CCAssignFnForReturn(F.getCallingConv(), F.isVarArg());
-
+  SmallVector<ArgInfo, 4> SplitVTs;
   ArgInfo RetInfo(VReg, Val->getType());
   setArgFlags(RetInfo, AttributeSet::ReturnIndex, DL, F);
+  splitToValueTypes(RetInfo, SplitVTs, DL, MF.getRegInfo());
+
+  CCAssignFn *AssignFn =
+      TLI.CCAssignFnForReturn(F.getCallingConv(), F.isVarArg());
 
   FuncReturnHandler RetHandler(MIRBuilder, MF.getRegInfo(), Ret, AssignFn);
-  return handleAssignments(MIRBuilder, RetInfo, RetHandler);
+  return handleAssignments(MIRBuilder, SplitVTs, RetHandler);
 }
 
 bool ARMCallLowering::lowerReturn(MachineIRBuilder &MIRBuilder,
@@ -179,7 +201,8 @@ bool ARMCallLowering::lowerFormalArguments(MachineIRBuilder &MIRBuilder,
   if (F.isVarArg())
     return false;
 
-  auto DL = MIRBuilder.getMF().getDataLayout();
+  auto &MF = MIRBuilder.getMF();
+  auto DL = MF.getDataLayout();
   auto &TLI = *getTLI<ARMTargetLowering>();
 
   if (TLI.getSubtarget()->isThumb())
@@ -198,7 +221,7 @@ bool ARMCallLowering::lowerFormalArguments(MachineIRBuilder &MIRBuilder,
   for (auto &Arg : Args) {
     ArgInfo AInfo(VRegs[Idx], Arg.getType());
     setArgFlags(AInfo, Idx + 1, DL, F);
-    ArgInfos.push_back(AInfo);
+    splitToValueTypes(AInfo, ArgInfos, DL, MF.getRegInfo());
     Idx++;
   }