[llvm] r249560 - [ARM] Prevent PerformVDIVCombine from combining a vcvt/vdiv with 8 lanes.

[Chad Rosier via llvm-commits]

Author: mcrosier
Date: Wed Oct  7 11:15:40 2015
New Revision: 249560

URL: http://llvm.org/viewvc/llvm-project?rev=249560&view=rev
Log:
[ARM] Prevent PerformVDIVCombine from combining a vcvt/vdiv with 8 lanes.

This would result in a crash since the vcvt used does not support v8i32 types.

Modified:
    llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
    llvm/trunk/test/CodeGen/ARM/vdiv_combine.ll

Modified: llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp?rev=249560&r1=249559&r2=249560&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp Wed Oct  7 11:15:40 2015
@@ -9908,10 +9908,12 @@ static SDValue PerformVDIVCombine(SDNode
   uint32_t FloatBits = FloatTy.getSizeInBits();
   MVT IntTy = Op.getOperand(0).getSimpleValueType().getVectorElementType();
   uint32_t IntBits = IntTy.getSizeInBits();
-  if (FloatBits != 32 || IntBits > 32) {
+  unsigned NumLanes = Op.getValueType().getVectorNumElements();
+  if (FloatBits != 32 || IntBits > 32 || NumLanes > 4) {
     // These instructions only exist converting from i32 to f32. We can handle
     // smaller integers by generating an extra extend, but larger ones would
-    // be lossy.
+    // be lossy. We also can't handle more then 4 lanes, since these intructions
+    // only support v2i32/v4i32 types.
     return SDValue();
   }
 
@@ -9922,7 +9924,6 @@ static SDValue PerformVDIVCombine(SDNode
 
   SDLoc dl(N);
   SDValue ConvInput = Op.getOperand(0);
-  unsigned NumLanes = Op.getValueType().getVectorNumElements();
   if (IntBits < FloatBits)
     ConvInput = DAG.getNode(isSigned ? ISD::SIGN_EXTEND : ISD::ZERO_EXTEND,
                             dl, NumLanes == 2 ? MVT::v2i32 : MVT::v4i32,

Modified: llvm/trunk/test/CodeGen/ARM/vdiv_combine.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/vdiv_combine.ll?rev=249560&r1=249559&r2=249560&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/vdiv_combine.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/vdiv_combine.ll Wed Oct  7 11:15:40 2015
@@ -136,3 +136,11 @@ define <2 x double> @fix_i64_to_double(<
     ret <2 x double> %shift
 }
 
+; Don't combine with 8 lanes.  Just make sure things don't crash.
+; CHECK-LABEL: test7
+define <8 x float> @test7(<8 x i32> %in) nounwind {
+entry:
+  %vcvt.i = sitofp <8 x i32> %in to <8 x float>
+  %div.i = fdiv <8 x float> %vcvt.i, <float 8.0, float 8.0, float 8.0, float 8.0, float 8.0, float 8.0, float 8.0, float 8.0>
+  ret <8 x float> %div.i
+}