[X86]Fix a crash trying to convert indices to proper type.

[ABataev]

Summary

Need to perform a bitcast on IndicesVec rather than subvector extract if the original size of the IndicesVec is the same as the size of the destination type.

[RKSimon]

llvm/test/CodeGen/X86/vector-extract-bitcast.ll

2

It'd be better to add this test inside var-permute-128.ll I think.

4

Please can you drop the local_unnamed_addr and give function a better name

[ABataev]

Address comments

[RKSimon]

LGTM

llvm/lib/Target/X86/X86ISelLowering.cpp

static SDValue createVariablePermute(MVT VT, SDValue SrcVec, SDValue IndicesVec,
   MVT ShuffleVT = VT;
   EVT IndicesVT = EVT(VT).changeVectorElementTypeToInteger();
   unsigned NumElts = VT.getVectorNumElements();
   unsigned SizeInBits = VT.getSizeInBits();
 
   // Adjust IndicesVec to match VT size.
   assert(IndicesVec.getValueType().getVectorNumElements() >= NumElts &&
          "Illegal variable permute mask size");
-  if (IndicesVec.getValueType().getVectorNumElements() > NumElts)
+  if (IndicesVec.getValueType().getVectorNumElements() > NumElts) {
+    if (IndicesVec.getValueSizeInBits() == SizeInBits)
+      IndicesVec = DAG.getBitcast(IndicesVT, IndicesVec);
+    else
       IndicesVec = extractSubVector(IndicesVec, 0, DAG, SDLoc(IndicesVec),
                                     NumElts * VT.getScalarSizeInBits());
+  }
   IndicesVec = DAG.getZExtOrTrunc(IndicesVec, SDLoc(IndicesVec), IndicesVT);
 
   // Handle SrcVec that don't match VT type.
   if (SrcVec.getValueSizeInBits() != SizeInBits) {
     if ((SrcVec.getValueSizeInBits() % SizeInBits) == 0) {
       // Handle larger SrcVec by treating it as a larger permute.
       unsigned Scale = SrcVec.getValueSizeInBits() / SizeInBits;
       VT = MVT::getVectorVT(VT.getScalarType(), Scale * NumElts);

llvm/test/CodeGen/X86/vector-extract-bitcast.ll

+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+avx | FileCheck %s
+
+define void @_Z1fv() local_unnamed_addr {
+; CHECK-LABEL: _Z1fv:
+; CHECK:       # %bb.0: # %bb
+; CHECK-NEXT:    vpshufd {{.*#+}} xmm0 = mem[2,3,2,3]
+; CHECK-NEXT:    vpand {{.*}}(%rip), %xmm0, %xmm0
+; CHECK-NEXT:    vmovapd (%rax), %xmm1
+; CHECK-NEXT:    vpaddq %xmm0, %xmm0, %xmm0
+; CHECK-NEXT:    vpermilpd %xmm0, %xmm1, %xmm0
+; CHECK-NEXT:    vmovupd %xmm0, (%rax)
+; CHECK-NEXT:    retq
+bb:
+  %0 = load <4 x i64>, <4 x i64>* undef, align 32
+  %1 = bitcast <4 x i64> %0 to <8 x i32>
+  %2 = shufflevector <8 x i32> %1, <8 x i32> undef, <2 x i32> <i32 2, i32 12>
+  %3 = and <2 x i32> %2, <i32 7, i32 7>
+  %4 = extractelement <2 x i32> %3, i32 0
+  %vecext.i8.1 = extractelement <4 x i64> %0, i32 %4
+  %5 = extractelement <2 x i32> %3, i32 1
+  %vecext.i8.2 = extractelement <4 x i64> %0, i32 %5
+  %6 = insertelement <2 x i64> poison, i64 %vecext.i8.1, i32 0
+  %7 = insertelement <2 x i64> %6, i64 %vecext.i8.2, i32 1
+  %8 = select <2 x i1> undef, <2 x i64> undef, <2 x i64> %7
+  store <2 x i64> %8, <2 x i64>* undef, align 8
+  ret void
+}
+