[ARM64] Fix "Cannot select" for vector ctpop

The commit of r205855:

Author: Arnold Schwaighofer <aschwaighofer@apple.com>
Date:   Wed Apr 9 14:20:47 2014 +0000

    SLPVectorizer: Only vectorize intrinsics whose operands are widened equally

    The vectorizer only knows how to vectorize intrinics by widening all operands by
    the same factor.

    Patch by Tyler Nowicki!

exposed a backend bug causing a regression (Cannot select ctpop).

The commit msg is a bit confusing because the patch actually changes the
behavior for the loop-vectorizer as well.  As things got refactored into a
helper ctpop got snuck in to the trivially-vectorizable helper which is now
used by both vectorizers.  In other words, we started seeing vector-ctpops in
the backend.

This change makes ctpop LegalizeAction::Expand for the types not supported by
the byte-only CNT instruction.  We may be able to custom-lower these later to
a single CNT but this is to fix the compiler crash first.

Fixes <rdar://problem/16578951>

llvm-svn: 206433

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Target/ARM64/ARM64ISelLowering.cpp b/llvm/lib/Target/ARM64/ARM64ISelLowering.cpp
index adf8abb57b5..aae018d4e28 100644
--- a/llvm/lib/Target/ARM64/ARM64ISelLowering.cpp
+++ b/llvm/lib/Target/ARM64/ARM64ISelLowering.cpp
@@ -504,6 +504,10 @@ void ARM64TargetLowering::addTypeForNEON(EVT VT, EVT PromotedBitwiseVT) {
   setOperationAction(ISD::VSELECT, VT.getSimpleVT(), Expand);
   setLoadExtAction(ISD::EXTLOAD, VT.getSimpleVT(), Expand);
 
+  // CNT supports only B element sizes.
+  if (VT != MVT::v8i8 && VT != MVT::v16i8)
+    setOperationAction(ISD::CTPOP, VT.getSimpleVT(), Expand);
+
   setOperationAction(ISD::UDIV, VT.getSimpleVT(), Expand);
   setOperationAction(ISD::SDIV, VT.getSimpleVT(), Expand);
   setOperationAction(ISD::UREM, VT.getSimpleVT(), Expand);