[PATCH] D26872: Outliner: Add MIR-level outlining pass

[Adrian Prantl via Phabricator via llvm-commits]

aprantl added inline comments.


================
Comment at: lib/CodeGen/MachineOutliner.cpp:199
+  while (EndIt != StartIt) {
+    MI = MF.CloneMachineInstr(&*EndIt);
+    MI->dropMemRefs();
----------------
aprantl wrote:
> aprantl wrote:
> > I looked at the implementation of MachineFunction::CloneMachineInstr() but I still can't tell:
> > What happens when the original instruction has a debug location on it - will it be stripped?
> > What happens when the original instruction is a DBG_VALUE - will it be copied?
> Did you get a chance to look into this?
Ping :-)

Note that it is really important to skip over any DBG_VALUE intrinsics while deciding whether to outline a sequence of instructions. Otherwise compiling with -g will produce different code than without, which we generally consider to be serious bug in the compiler.


Repository:
  rL LLVM

https://reviews.llvm.org/D26872