[WebAssembly] Add a TODO comment for a possible future optimization.

llvm-svn: 256306

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyRegNumbering.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyRegNumbering.cpp
index 0a945336a2b..f621db070b5 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyRegNumbering.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyRegNumbering.cpp
@@ -82,7 +82,8 @@ bool WebAssemblyRegNumbering::runOnMachineFunction(MachineFunction &MF) {
   }
 
   // Then assign regular WebAssembly registers for all remaining used
-  // virtual registers.
+  // virtual registers. TODO: Consider sorting the registers by frequency of
+  // use, to maximize usage of small immediate fields.
   unsigned NumArgRegs = MFI.getParams().size();
   unsigned NumVRegs = MF.getRegInfo().getNumVirtRegs();
   unsigned NumStackRegs = 0;