ARM: Implement CanLowerReturn so large vectors get expanded into sret.

Fixes 14337.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168809 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index bd470eb..b2af378 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -1882,6 +1882,17 @@
   return true;
 }
 
+bool
+ARMTargetLowering::CanLowerReturn(CallingConv::ID CallConv,
+                                  MachineFunction &MF, bool isVarArg,
+                                  const SmallVectorImpl<ISD::OutputArg> &Outs,
+                                  LLVMContext &Context) const {
+  SmallVector<CCValAssign, 16> RVLocs;
+  CCState CCInfo(CallConv, isVarArg, MF, getTargetMachine(), RVLocs, Context);
+  return CCInfo.CheckReturn(Outs, CCAssignFnForNode(CallConv, /*Return=*/true,
+                                                    isVarArg));
+}
+
 SDValue
 ARMTargetLowering::LowerReturn(SDValue Chain,
                                CallingConv::ID CallConv, bool isVarArg,
diff --git a/lib/Target/ARM/ARMISelLowering.h b/lib/Target/ARM/ARMISelLowering.h
index 8bf803e..9cbf866 100644
--- a/lib/Target/ARM/ARMISelLowering.h
+++ b/lib/Target/ARM/ARMISelLowering.h
@@ -495,6 +495,12 @@
                                     const SmallVectorImpl<SDValue> &OutVals,
                                     const SmallVectorImpl<ISD::InputArg> &Ins,
                                            SelectionDAG& DAG) const;
+
+    virtual bool CanLowerReturn(CallingConv::ID CallConv,
+                                MachineFunction &MF, bool isVarArg,
+                                const SmallVectorImpl<ISD::OutputArg> &Outs,
+                                LLVMContext &Context) const;
+
     virtual SDValue
       LowerReturn(SDValue Chain,
                   CallingConv::ID CallConv, bool isVarArg,
diff --git a/test/CodeGen/ARM/ret_sret_vector.ll b/test/CodeGen/ARM/ret_sret_vector.ll
new file mode 100644
index 0000000..9bb3519
--- /dev/null
+++ b/test/CodeGen/ARM/ret_sret_vector.ll
@@ -0,0 +1,12 @@
+; RUN: llc < %s | FileCheck %s
+
+target datalayout = "e-p:32:32:32-i1:8:32-i8:8:32-i16:16:32-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:32:64-v128:32:128-a0:0:32-n32-S32"
+target triple = "thumbv7-apple-ios3.0.0"
+
+define <4 x double> @PR14337(<4 x double> %a, <4 x double> %b) {
+  %foo = fadd <4 x double>  %a, %b
+  ret <4 x double> %foo
+; CHECK: PR14337:
+; CHECK: vst1.64
+; CHECK: vst1.64
+}