[llvm] Fix the computation of size of gshared instances in emit_args_…

…to_vtype ().

Fixes #13610.

mono/mini/generics.cs

@@ -1448,6 +1448,20 @@ public Type Caller<TAwaiter>(ref TAwaiter awaiter)
 		var res = builder.Caller (ref awaiter);
 		return res == typeof (bool) ? 0 : 1;
 	}
+
+	struct OneThing<T1> {
+		public T1 Item1;
+	}
+
+	[MethodImpl (MethodImplOptions.NoInlining)]
+	static T FromResult<T> (T result) {
+		return result;
+	}
+
+	public static int test_42_llvm_gsharedvt_small_vtype_in_regs () {
+		var t = FromResult<OneThing<int>>(new OneThing<int> {Item1 = 42});
+		return t.Item1;
+	}
 }
 
 #if !__MOBILE__

mono/mini/mini-llvm.c

@@ -2243,12 +2243,14 @@ static void
 emit_args_to_vtype (EmitContext *ctx, LLVMBuilderRef builder, MonoType *t, LLVMValueRef address, LLVMArgInfo *ainfo, LLVMValueRef *args)
 {
 	int j, size, nslots;
+	MonoClass *klass;
 
-	size = mono_class_value_size (mono_class_from_mono_type (t), NULL);
+	t = mini_get_underlying_type (t);
+	klass = mono_class_from_mono_type (t);
+	size = mono_class_value_size (klass, NULL);
 
-	if (MONO_CLASS_IS_SIMD (ctx->cfg, mono_class_from_mono_type (t))) {
+	if (MONO_CLASS_IS_SIMD (ctx->cfg, klass))
 		address = LLVMBuildBitCast (ctx->builder, address, LLVMPointerType (LLVMInt8Type (), 0), "");
-	}
 
 	if (ainfo->storage == LLVMArgAsFpArgs)
 		nslots = ainfo->nslots;
@@ -2269,8 +2271,8 @@ emit_args_to_vtype (EmitContext *ctx, LLVMBuilderRef builder, MonoType *t, LLVMV
 		switch (ainfo->pair_storage [j]) {
 		case LLVMArgInIReg: {
 			part_type = LLVMIntType (part_size * 8);
-			if (MONO_CLASS_IS_SIMD (ctx->cfg, mono_class_from_mono_type (t))) {
-				index [0] = LLVMConstInt (LLVMInt32Type (), j * sizeof (gpointer), FALSE);
+			if (MONO_CLASS_IS_SIMD (ctx->cfg, klass)) {
+				index [0] = LLVMConstInt (LLVMInt32Type (), j * TARGET_SIZEOF_VOID_P, FALSE);
 				addr = LLVMBuildGEP (builder, address, index, 1, "");
 			} else {
 				daddr = LLVMBuildBitCast (ctx->builder, address, LLVMPointerType (IntPtrType (), 0), "");

mono/mini/mini.h

@@ -620,7 +620,7 @@ typedef struct {
 	LLVMArgStorage storage;
 
 	/*
-	 * Only if storage == ArgValuetypeInReg/LLVMArgAsFpArgs.
+	 * Only if storage == ArgVtypeInReg/LLVMArgAsFpArgs.
 	 * This contains how the parts of the vtype are passed.
 	 */
 	LLVMArgStorage pair_storage [8];