[PATCH] D27705: [ARM] GlobalISel: Support i8/i16 ABI extensions

[Diana Picus via Phabricator via llvm-commits]

rovka added inline comments.


================
Comment at: lib/Target/ARM/ARMInstructionSelector.cpp:78
+  if (Opc == G_SEXT)
+    return Size == 8 ? ARM::SXTB : ARM::SXTH;
+
----------------
t.p.northover wrote:
> If we don't already, it would be a very good idea to make sure we bail completely in Thumb mode. Incidentally, is there any particular reason you decided to go for ARM first? I thought most things were compiled in Thumb these days.
I'm mostly going with ARM first because it seems simpler than Thumb.
At the moment I'm trying to focus on the call lowering + what it needs to get some simple examples through the entire pipeline. I don't want to beef up the instruction selector too much, because that will go away anyway when we move to TableGen. So for instance we can select the extensions that we need for the ABI zeroext/signext, but I'm not really in any rush right now to add other extensions (e.g. from i8 to i16 or whatever).
I'm open to suggestions if this sounds like a bad plan :)


https://reviews.llvm.org/D27705