[PowerPC] Add a FIXME.

Documenting a design choice to generate only medium model sequences for TLS
addresses at this time.  Small and large code models could be supported if
necessary.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190883 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp
index 83bd1abddedb98ed38596f153e8bc0ac9fb7b133..5e12664e728ca56ee5309e8611c08ebaa4c01810 100644 (file)
--- a/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -1408,6 +1408,10 @@ SDValue PPCTargetLowering::LowerBlockAddress(SDValue Op,
 SDValue PPCTargetLowering::LowerGlobalTLSAddress(SDValue Op,
                                               SelectionDAG &DAG) const {
 
+  // FIXME: TLS addresses currently use medium model code sequences,
+  // which is the most useful form.  Eventually support for small and
+  // large models could be added if users need it, at the cost of
+  // additional complexity.
   GlobalAddressSDNode *GA = cast<GlobalAddressSDNode>(Op);
   SDLoc dl(GA);
   const GlobalValue *GV = GA->getGlobal();