[ARM64] Incorrect HFA/HVA property calculation #35144
Description
While reviewing changes in dotnet/coreclr#23675, I noticed that the code added to EEClass::CheckForHFA does not handle wrapped Vector64, Vector128, and Vector256 intrinsic types correctly. For instance, it does not distinguish a wrapped Vector64 and a double. Moreover, the elemSize check is skipped for wrapped Vector128 and Vector256 types. As a result, the HFA/HVA property may be calculated incorrectly. For instance (here { } denotes a struct):
{{Vector64}, Vector64}is incorrectly treated as non-HVA.{{Vector64}, double}is incorrectly treated as HFA(double).{Vector128, {Vector256}}is incorrectly treated as HVA(simd16).
The code in question:
runtime/src/coreclr/src/vm/class.cpp
Lines 1345 to 1381 in ce416f4
The repro program (set COMPlus_JITDisasm=C::* to see HFA/HVA properties and registers used):
using System.Runtime.CompilerServices;
using System.Runtime.Intrinsics;
#pragma warning disable 0169 // warning CS0169: The field '{0}' is never used
struct WrappedVector64 { Vector64<byte> _; }
struct WrappedVector128 { Vector128<byte> _; }
struct WrappedVector256 { Vector256<byte> _; }
// Incorrectly treated as non-HVA: passed in x0, x1
struct S1 { WrappedVector64 x; Vector64<byte> y; }
// Incorrectly treated as HFA(double): passed in d0, d1
struct S2 { WrappedVector64 x; double y; }
// Incorrectly treated as HVA(simd16): passed in q0, q1, q2
struct S3 { Vector128<byte> x; WrappedVector256 y; }
static class C
{
[MethodImpl(MethodImplOptions.NoInlining)]
static void Foo<T>(T x) { }
static void Main()
{
Foo(new S1());
Foo(new S2());
Foo(new S3());
}
}@CarolEidt @echesakovMSFT @sdmaclea