[XCore] Support functions returning more than 4 words.

If a function returns a large struct by value return the first 4 words
in registers and the rest on the stack in a location reserved by the
caller. This is needed to support the xC language which supports
functions returning an arbitrary number of return values. This is
r202397 reapplied with a fix to avoid an uninitialized read of a member.

llvm-svn: 202414

1 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/Target/XCore/XCoreCallingConv.td b/llvm/lib/Target/XCore/XCoreCallingConv.td
index b20d71f49cf..e149e6d9ec2 100644
--- a/llvm/lib/Target/XCore/XCoreCallingConv.td
+++ b/llvm/lib/Target/XCore/XCoreCallingConv.td
@@ -14,7 +14,11 @@
 //===----------------------------------------------------------------------===//
 def RetCC_XCore : CallingConv<[
   // i32 are returned in registers R0, R1, R2, R3
-  CCIfType<[i32], CCAssignToReg<[R0, R1, R2, R3]>>
+  CCIfType<[i32], CCAssignToReg<[R0, R1, R2, R3]>>,
+
+  // Integer values get stored in stack slots that are 4 bytes in
+  // size and 4-byte aligned.
+  CCIfType<[i32], CCAssignToStack<4, 4>>
 ]>;
 
 //===----------------------------------------------------------------------===//