[llvm] r216725 - AArch64: skip select/setcc combine in complex case.

[Tim Northover]

Author: tnorthover
Date: Fri Aug 29 08:05:18 2014
New Revision: 216725

URL: http://llvm.org/viewvc/llvm-project?rev=216725&view=rev
Log:
AArch64: skip select/setcc combine in complex case.

In an llvm-stress generated test, we were trying to create a v0iN type and
asserting when that failed. This case could probably be handled by the
function, but not without added complexity and the situation it arises in is
sufficiently odd that there's probably no benefit anyway.

Should fix PR20775.

Modified:
    llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp
    llvm/trunk/test/CodeGen/AArch64/cond-sel.ll

Modified: llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp?rev=216725&r1=216724&r2=216725&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/AArch64/AArch64ISelLowering.cpp Fri Aug 29 08:05:18 2014
@@ -7994,22 +7994,24 @@ static SDValue performVSelectCombine(SDN
 static SDValue performSelectCombine(SDNode *N, SelectionDAG &DAG) {
   SDValue N0 = N->getOperand(0);
   EVT ResVT = N->getValueType(0);
+  EVT SrcVT = N0.getOperand(0).getValueType();
+  int NumMaskElts = ResVT.getSizeInBits() / SrcVT.getSizeInBits();
 
-  if (!N->getOperand(1).getValueType().isVector())
+  // If NumMaskElts == 0, the comparison is larger than select result. The
+  // largest real NEON comparison is 64-bits per lane, which means the result is
+  // at most 32-bits and an illegal vector. Just bail out for now.
+  if (!ResVT.isVector() || NumMaskElts == 0)
     return SDValue();
 
   if (N0.getOpcode() != ISD::SETCC || N0.getValueType() != MVT::i1)
     return SDValue();
 
-  SDLoc DL(N0);
-
-  EVT SrcVT = N0.getOperand(0).getValueType();
-  SrcVT = EVT::getVectorVT(*DAG.getContext(), SrcVT,
-                           ResVT.getSizeInBits() / SrcVT.getSizeInBits());
+  SrcVT = EVT::getVectorVT(*DAG.getContext(), SrcVT, NumMaskElts);
   EVT CCVT = SrcVT.changeVectorElementTypeToInteger();
 
   // First perform a vector comparison, where lane 0 is the one we're interested
   // in.
+  SDLoc DL(N0);
   SDValue LHS =
       DAG.getNode(ISD::SCALAR_TO_VECTOR, DL, SrcVT, N0.getOperand(0));
   SDValue RHS =
@@ -8019,8 +8021,8 @@ static SDValue performSelectCombine(SDNo
   // Now duplicate the comparison mask we want across all other lanes.
   SmallVector<int, 8> DUPMask(CCVT.getVectorNumElements(), 0);
   SDValue Mask = DAG.getVectorShuffle(CCVT, DL, SetCC, SetCC, DUPMask.data());
-  Mask = DAG.getNode(ISD::BITCAST, DL, ResVT.changeVectorElementTypeToInteger(),
-                     Mask);
+  Mask = DAG.getNode(ISD::BITCAST, DL,
+                     ResVT.changeVectorElementTypeToInteger(), Mask);
 
   return DAG.getSelect(DL, ResVT, Mask, N->getOperand(1), N->getOperand(2));
 }

Modified: llvm/trunk/test/CodeGen/AArch64/cond-sel.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/cond-sel.ll?rev=216725&r1=216724&r2=216725&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/cond-sel.ll (original)
+++ llvm/trunk/test/CodeGen/AArch64/cond-sel.ll Fri Aug 29 08:05:18 2014
@@ -214,3 +214,13 @@ define void @test_csetm(i32 %lhs, i32 %r
   ret void
 ; CHECK: ret
 }
+
+define <1 x i1> @test_wide_comparison(i32 %in) {
+; CHECK-LABEL: test_wide_comparison:
+; CHECK: cmp w0, #1234
+; CHECK: cset
+
+  %tmp = icmp sgt i32 %in, 1234
+  %res = select i1 %tmp, <1 x i1> <i1 1>, <1 x i1> zeroinitializer
+  ret <1 x i1> %res
+}