X86: correct tail return address calculation

Due to the weird and wondeful usual arithmetic conversions, some
calculations involving negative values were getting performed in
uint32_t and then promoted to int64_t, which is really not a good
idea.

Patch by Katsuhiro Ueno.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187703 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 1f6c330..dc56547 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -2456,7 +2456,8 @@
   if (!FPDiff) return Chain;
   // Calculate the new stack slot for the return address.
   int NewReturnAddrFI =
-    MF.getFrameInfo()->CreateFixedObject(SlotSize, FPDiff-SlotSize, false);
+    MF.getFrameInfo()->CreateFixedObject(SlotSize, (int64_t)FPDiff - SlotSize,
+                                         false);
   SDValue NewRetAddrFrIdx = DAG.getFrameIndex(NewReturnAddrFI, PtrVT);
   Chain = DAG.getStore(Chain, dl, RetAddrFrIdx, NewRetAddrFrIdx,
                        MachinePointerInfo::getFixedStack(NewReturnAddrFI),
@@ -3323,7 +3324,8 @@
   if (ReturnAddrIndex == 0) {
     // Set up a frame object for the return address.
     unsigned SlotSize = RegInfo->getSlotSize();
-    ReturnAddrIndex = MF.getFrameInfo()->CreateFixedObject(SlotSize, -SlotSize,
+    ReturnAddrIndex = MF.getFrameInfo()->CreateFixedObject(SlotSize,
+                                                           -(int64_t)SlotSize,
                                                            false);
     FuncInfo->setRAIndex(ReturnAddrIndex);
   }