[llvm] Fix the returning of vtypes using a hidden argument in bitcode, in some cases, we forgot to generate the code to return the value, causing random data to be returned. Fixes #59956. (#5786)mono-5.4.1.72017-06

2 files changed, 61 insertions, 0 deletions

diff --git a/mono/mini/gshared.cs b/mono/mini/gshared.cs
index 61402f7a4ec..910a6df73f5 100644
--- a/mono/mini/gshared.cs
+++ b/mono/mini/gshared.cs
@@ -1996,6 +1996,23 @@ public class Tests
 		Console.WriteLine ("X: " + iface.is_ref<AStruct3<string, int, int>> ());
 		return 0;
 	}
+
+	interface IFace59956 {
+		int foo<T> ();
+	}
+
+	class Impl59956 : IFace59956 {
+		public int foo<T> () {
+			var builder = new SparseArrayBuilder<T>(true);
+
+			return builder.Markers._count;
+		}
+	}
+
+	public static int test_1_59956_regress () {
+		IFace59956 iface = new Impl59956 ();
+		return iface.foo<int> ();
+	}
 }
 
 // #13191
@@ -2013,6 +2030,35 @@ public class MobileServiceCollection<TTable, TCol>
 	}
 }
 
+// #59956
+internal struct Marker
+{
+	public Marker(int count, int index) {
+	}
+}
+
+public struct ArrayBuilder<T>
+{
+	private T[] _array;
+	public int _count;
+
+	public ArrayBuilder(int capacity) {
+		_array = new T[capacity];
+		_count = 1;
+	}
+}
+
+internal struct SparseArrayBuilder<T>
+{
+	private ArrayBuilder<Marker> _markers;
+
+	public SparseArrayBuilder(bool initialize) : this () {
+		_markers = new ArrayBuilder<Marker> (10);
+	}
+
+	public ArrayBuilder<Marker> Markers => _markers;
+}
+
 #if !__MOBILE__
 public class GSharedTests : Tests {
 }
diff --git a/mono/mini/mini-llvm.c b/mono/mini/mini-llvm.c
index 694189a96ac..79b0c8585ae 100644
--- a/mono/mini/mini-llvm.c
+++ b/mono/mini/mini-llvm.c
@@ -7492,7 +7492,22 @@ mono_llvm_create_vars (MonoCompile *cfg)
 
 	sig = mono_method_signature (cfg->method);
 	if (cfg->gsharedvt && cfg->llvm_only) {
+		gboolean vretaddr = FALSE;
+
 		if (mini_is_gsharedvt_variable_signature (sig) && sig->ret->type != MONO_TYPE_VOID) {
+			vretaddr = TRUE;
+		} else {
+			MonoMethodSignature *sig = mono_method_signature (cfg->method);
+			LLVMCallInfo *linfo;
+
+			linfo = get_llvm_call_info (cfg, sig);
+			vretaddr = (linfo->ret.storage == LLVMArgVtypeRetAddr || linfo->ret.storage == LLVMArgVtypeByRef || linfo->ret.storage == LLVMArgGsharedvtFixed || linfo->ret.storage == LLVMArgGsharedvtVariable || linfo->ret.storage == LLVMArgGsharedvtFixedVtype);
+		}
+		if (vretaddr) {
+			/*
+			 * Creating vret_addr forces CEE_SETRET to store the result into it,
+			 * so we don't have to generate any code in our OP_SETRET case.
+			 */
 			cfg->vret_addr = mono_compile_create_var (cfg, &mono_get_intptr_class ()->byval_arg, OP_ARG);
 			if (G_UNLIKELY (cfg->verbose_level > 1)) {
 				printf ("vret_addr = ");