[llvm] r206433 - [ARM64] Fix "Cannot select" for vector ctpop

[Adam Nemet]

Author: anemet
Date: Wed Apr 16 20:01:37 2014
New Revision: 206433

URL: http://llvm.org/viewvc/llvm-project?rev=206433&view=rev
Log:
[ARM64] Fix "Cannot select" for vector ctpop

The commit of r205855:

Author: Arnold Schwaighofer <aschwaighofer at 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>

Added:
    llvm/trunk/test/CodeGen/ARM64/vpopcnt.ll
Modified:
    llvm/trunk/lib/Target/ARM64/ARM64ISelLowering.cpp

Modified: llvm/trunk/lib/Target/ARM64/ARM64ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM64/ARM64ISelLowering.cpp?rev=206433&r1=206432&r2=206433&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM64/ARM64ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/ARM64/ARM64ISelLowering.cpp Wed Apr 16 20:01:37 2014
@@ -504,6 +504,10 @@ void ARM64TargetLowering::addTypeForNEON
   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);

Added: llvm/trunk/test/CodeGen/ARM64/vpopcnt.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM64/vpopcnt.ll?rev=206433&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/ARM64/vpopcnt.ll (added)
+++ llvm/trunk/test/CodeGen/ARM64/vpopcnt.ll Wed Apr 16 20:01:37 2014
@@ -0,0 +1,68 @@
+; RUN: llc < %s -march=arm64 -mcpu=cyclone | FileCheck %s
+target triple = "arm64-apple-ios"
+
+; The non-byte ones used to fail with "Cannot select"
+
+; CHECK-LABEL: ctpopv8i8
+; CHECK: cnt.8b
+define <8 x i8> @ctpopv8i8(<8 x i8> %x) nounwind readnone {
+  %cnt = tail call <8 x i8> @llvm.ctpop.v8i8(<8 x i8> %x)
+  ret <8 x i8> %cnt
+}
+
+declare <8 x i8> @llvm.ctpop.v8i8(<8 x i8>) nounwind readnone
+
+; CHECK-LABEL: ctpopv4i16
+; CHECK: cnt.8b
+define <4 x i16> @ctpopv4i16(<4 x i16> %x) nounwind readnone {
+  %cnt = tail call <4 x i16> @llvm.ctpop.v4i16(<4 x i16> %x)
+  ret <4 x i16> %cnt
+}
+
+declare <4 x i16> @llvm.ctpop.v4i16(<4 x i16>) nounwind readnone
+
+; CHECK-LABEL: ctpopv2i32
+; CHECK: cnt.8b
+define <2 x i32> @ctpopv2i32(<2 x i32> %x) nounwind readnone {
+  %cnt = tail call <2 x i32> @llvm.ctpop.v2i32(<2 x i32> %x)
+  ret <2 x i32> %cnt
+}
+
+declare <2 x i32> @llvm.ctpop.v2i32(<2 x i32>) nounwind readnone
+
+
+; CHECK-LABEL: ctpopv16i8
+; CHECK: cnt.16b
+define <16 x i8> @ctpopv16i8(<16 x i8> %x) nounwind readnone {
+  %cnt = tail call <16 x i8> @llvm.ctpop.v16i8(<16 x i8> %x)
+  ret <16 x i8> %cnt
+}
+
+declare <16 x i8> @llvm.ctpop.v16i8(<16 x i8>) nounwind readnone
+
+; CHECK-LABEL: ctpopv8i16
+; CHECK: cnt.8b
+define <8 x i16> @ctpopv8i16(<8 x i16> %x) nounwind readnone {
+  %cnt = tail call <8 x i16> @llvm.ctpop.v8i16(<8 x i16> %x)
+  ret <8 x i16> %cnt
+}
+
+declare <8 x i16> @llvm.ctpop.v8i16(<8 x i16>) nounwind readnone
+
+; CHECK-LABEL: ctpopv4i32
+; CHECK: cnt.8b
+define <4 x i32> @ctpopv4i32(<4 x i32> %x) nounwind readnone {
+  %cnt = tail call <4 x i32> @llvm.ctpop.v4i32(<4 x i32> %x)
+  ret <4 x i32> %cnt
+}
+
+declare <4 x i32> @llvm.ctpop.v4i32(<4 x i32>) nounwind readnone
+
+; CHECK-LABEL: ctpopv2i64
+; CHECK: cnt.8b
+define <2 x i64> @ctpopv2i64(<2 x i64> %x) nounwind readnone {
+  %cnt = tail call <2 x i64> @llvm.ctpop.v2i64(<2 x i64> %x)
+  ret <2 x i64> %cnt
+}
+
+declare <2 x i64> @llvm.ctpop.v2i64(<2 x i64>) nounwind readnone