[X86][CodeGen]Fix extract f16 from big vectors

[XinWang10]

Summary

When use llc -mattr=+avx512fp16, it will crash.

define half @test(<64 x half> %x, i64 %idx){
   %res = extractelement <64 x half> %x, i64 %idx
   ret half %res
}

The root cause is when we enable avx512fp16 we lose custom handler
for extract f16 from big vectors which is not loaded from pointer.

[XinWang10]

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[XinWang10]

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[XinWang10]

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[XinWang10]

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[XinWang10]

Fix extract f16 from big vectors

[pengfei]

llvm/lib/Target/X86/X86ISelLowering.cpp

34125

We usually use vNf16

34126–34128

Try to avoid defining variable used by assert only. Compiler may report used variable when do releast build.

34131–34132

You can use changeVectorElementTypeToInteger.

llvm/test/CodeGen/X86/avx512fp16-mov.ll

1352 ↗

(On Diff #487682)

Add nounwind.

[XinWang10]

Updating D141348: [X86][CodeGen]Fix extract f16 from big vectors

[pengfei]

llvm/lib/Target/X86/X86ISelLowering.cpp

34125

Sorry, I want to say vXf16.

[XinWang10]

Change tests

[XinWang10]

Update comments

[XinWang10]

llvm/lib/Target/X86/X86ISelLowering.cpp

34125

Thanks.

[pengfei]

LGTM.

llvm/lib/Target/X86/X86ISelLowering.cpp

     assert(N->getValueType(0) == MVT::i64 && "Unexpected VT!");
     assert(Subtarget.hasXOP() && "Expected XOP");
     // We can use VPPERM by copying to a vector register and back. We'll need
     // to move the scalar in two i32 pieces.
     Results.push_back(LowerBITREVERSE(SDValue(N, 0), Subtarget, DAG));
     return;
   }
   case ISD::EXTRACT_VECTOR_ELT: {
     // f16 = extract vxxf16 %vec, i64 %idx
     MVT SplitVT = N->getSimpleValueType(0);
     assert(SplitVT == MVT::f16 &&
            "Unexpected Value type of EXTRACT_VECTOR_ELT!");
-    assert(Subtarget.HasFP16() && "Expected FP16");
+    assert(Subtarget.hasFP16() && "Expected FP16");
     SDValue VecOp = N->getOperand(0);
     MVT ExtVT =
         MVT::getVectorVT(MVT::i16, VecOp.getValueType().getVectorNumElements());
     SDValue Split = DAG.getBitcast(ExtVT, N->getOperand(0));
     Split = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, MVT::i16, Split,
                         N->getOperand(1));
     Split = DAG.getBitcast(MVT::f16, Split);
     Results.push_back(Split);
     return;
   }
   }