From 9d652a972a015187b870c35057e7be1fa9c6852f Mon Sep 17 00:00:00 2001
From: Zoltan Varga <vargaz@gmail.com>
Date: Tue, 26 Mar 2019 11:28:59 -0400
Subject: [PATCH] [llvm] Fix the computation of size of gshared instances in
 emit_args_to_vtype (). (#13659)

Fixes https://github.com/mono/mono/issues/13610.
---
 mono/mini/generics.cs | 14 ++++++++++++++
 mono/mini/mini-llvm.c | 10 ++++++----
 mono/mini/mini.h      |  2 +-
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/mono/mini/generics.cs b/mono/mini/generics.cs
index 6cb61e16e1a..857ad44f3e0 100644
--- a/mono/mini/generics.cs
+++ b/mono/mini/generics.cs
@@ -1448,6 +1448,20 @@ class Tests
 		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__
diff --git a/mono/mini/mini-llvm.c b/mono/mini/mini-llvm.c
index 0373f143663..f21b7da44ca 100644
--- a/mono/mini/mini-llvm.c
+++ b/mono/mini/mini-llvm.c
@@ -2360,12 +2360,14 @@ 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_internal (t), NULL);
+	t = mini_get_underlying_type (t);
+	klass = mono_class_from_mono_type_internal (t);
+	size = mono_class_value_size (klass, NULL);
 
-	if (MONO_CLASS_IS_SIMD (ctx->cfg, mono_class_from_mono_type_internal (t))) {
+	if (MONO_CLASS_IS_SIMD (ctx->cfg, klass))
 		address = LLVMBuildBitCast (ctx->builder, address, LLVMPointerType (LLVMInt8Type (), 0), "");
-	}
 
 	if (ainfo->storage == LLVMArgAsFpArgs)
 		nslots = ainfo->nslots;
@@ -2386,7 +2388,7 @@ 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_internal (t))) {
+			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 {
diff --git a/mono/mini/mini.h b/mono/mini/mini.h
index d7e182e2bdc..9358871dc93 100644
--- a/mono/mini/mini.h
+++ b/mono/mini/mini.h
@@ -623,7 +623,7 @@ 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];
-- 
2.11.4.GIT