Add code to check at SelectionDAGISel::LowerArguments time to see if return values can be lowered to registers. Coming soon, code to perform sret-demotion if return values cannot be lowered to registers

llvm-svn: 86324

1 files changed, 15 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/CallingConvLower.cpp b/llvm/lib/CodeGen/SelectionDAG/CallingConvLower.cpp
index fbe40b67863..38839c44131 100644
--- a/llvm/lib/CodeGen/SelectionDAG/CallingConvLower.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/CallingConvLower.cpp
@@ -77,6 +77,21 @@ CCState::AnalyzeFormalArguments(const SmallVectorImpl<ISD::InputArg> &Ins,
   }
 }
 
+/// CheckReturn - Analyze the return values of a function, returning true if
+/// the return can be performed without sret-demotion, and false otherwise.
+bool CCState::CheckReturn(const SmallVectorImpl<EVT> &OutTys,
+                          const SmallVectorImpl<ISD::ArgFlagsTy> &ArgsFlags,
+                          CCAssignFn Fn) {
+  // Determine which register each value should be copied into.
+  for (unsigned i = 0, e = OutTys.size(); i != e; ++i) {
+    EVT VT = OutTys[i];
+    ISD::ArgFlagsTy ArgFlags = ArgsFlags[i];
+    if (Fn(i, VT, VT, CCValAssign::Full, ArgFlags, *this))
+      return false;
+  }
+  return true;
+}
+
 /// AnalyzeReturn - Analyze the returned values of a return,
 /// incorporating info about the result values into this state.
 void CCState::AnalyzeReturn(const SmallVectorImpl<ISD::OutputArg> &Outs,