From 99db20f0bcf62c860f959cfed34bc29945fa3929 Mon Sep 17 00:00:00 2001
From: Zoltan Varga <vargaz@gmail.com>
Date: Wed, 8 Jan 2020 13:32:52 +0100
Subject: [PATCH] [jit] Implement fast TLS access in gshared methods.
 (mono/mono#18377)

Fixes https://github.com/mono/mono/issues/18370.

Commit migrated from https://github.com/mono/mono/commit/e999846088bb4b05b2fa22234bd70fb42fd02a80
---
 src/mono/mono/mini/generics.cs            | 22 ++++++++++++++++++++++
 src/mono/mono/mini/method-to-ir.c         | 16 ++++++++++------
 src/mono/mono/mini/mini-generic-sharing.c | 15 +++++++++++++++
 3 files changed, 47 insertions(+), 6 deletions(-)

diff --git a/src/mono/mono/mini/generics.cs b/src/mono/mono/mini/generics.cs
index 857ad44..0c6346c 100644
--- a/src/mono/mono/mini/generics.cs
+++ b/src/mono/mono/mini/generics.cs
@@ -1462,6 +1462,28 @@ class Tests
 		var t = FromResult<OneThing<int>>(new OneThing<int> {Item1 = 42});
 		return t.Item1;
 	}
+
+	class ThreadLocalClass<T> {
+		[ThreadStatic]
+		static T v;
+
+		public T Value {
+			[MethodImpl (MethodImplOptions.NoInlining)]
+			get {
+				return v;
+			}
+			[MethodImpl (MethodImplOptions.NoInlining)]
+			set {
+				v = value;
+			}
+		}
+	}
+
+	public static int test_0_tls_gshared () {
+		var c = new ThreadLocalClass<string> ();
+		c.Value = "FOO";
+		return c.Value == "FOO" ? 0 : 1;
+	}
 }
 
 #if !__MOBILE__
diff --git a/src/mono/mono/mini/method-to-ir.c b/src/mono/mono/mini/method-to-ir.c
index 5334e10..606655a 100644
--- a/src/mono/mono/mini/method-to-ir.c
+++ b/src/mono/mono/mini/method-to-ir.c
@@ -9385,7 +9385,8 @@ calli_end:
 				thread_ins = NULL;
 
 			/* Generate IR to compute the field address */
-			if (is_special_static && ((gsize)addr & 0x80000000) == 0 && thread_ins && !(cfg->opt & MONO_OPT_SHARED) && !context_used) {
+			if (is_special_static && ((gsize)addr & 0x80000000) == 0 && thread_ins && !(cfg->opt & MONO_OPT_SHARED) &&
+				!(context_used && cfg->gsharedvt && mini_is_gsharedvt_klass (klass))) {
 				/*
 				 * Fast access to TLS data
 				 * Inline version of get_thread_static_data () in
@@ -9394,17 +9395,20 @@ calli_end:
 				guint32 offset;
 				int idx, static_data_reg, array_reg, dreg;
 
-				if (context_used && cfg->gsharedvt && mini_is_gsharedvt_klass (klass))
-					GSHAREDVT_FAILURE (il_op);
-
 				static_data_reg = alloc_ireg (cfg);
 				MONO_EMIT_NEW_LOAD_MEMBASE (cfg, static_data_reg, thread_ins->dreg, MONO_STRUCT_OFFSET (MonoInternalThread, static_data));
 
-				if (cfg->compile_aot) {
+				if (cfg->compile_aot || context_used) {
 					int offset_reg, offset2_reg, idx_reg;
 
 					/* For TLS variables, this will return the TLS offset */
-					EMIT_NEW_SFLDACONST (cfg, ins, field);
+					if (context_used) {
+						MonoInst *addr_ins = emit_get_rgctx_field (cfg, context_used, field, MONO_RGCTX_INFO_FIELD_OFFSET);
+						/* The value is offset by 1 */
+						EMIT_NEW_BIALU_IMM (cfg, ins, OP_PSUB_IMM, addr_ins->dreg, addr_ins->dreg, 1);
+					} else {
+						EMIT_NEW_SFLDACONST (cfg, ins, field);
+					}
 					offset_reg = ins->dreg;
 					MONO_EMIT_NEW_BIALU_IMM (cfg, OP_IAND_IMM, offset_reg, offset_reg, 0x7fffffff);
 					idx_reg = alloc_ireg (cfg);
diff --git a/src/mono/mono/mini/mini-generic-sharing.c b/src/mono/mono/mini/mini-generic-sharing.c
index 279fbaf..5ee4434 100644
--- a/src/mono/mono/mini/mini-generic-sharing.c
+++ b/src/mono/mono/mini/mini-generic-sharing.c
@@ -2255,6 +2255,21 @@ instantiate_info (MonoDomain *domain, MonoRuntimeGenericContextInfoTemplate *oti
 	case MONO_RGCTX_INFO_FIELD_OFFSET: {
 		MonoClassField *field = (MonoClassField *)data;
 
+		if (mono_class_field_is_special_static (field)) {
+			gpointer addr;
+
+			mono_class_vtable_checked (domain, klass, error);
+			mono_error_assert_ok (error);
+
+			/* Return the TLS offset */
+			g_assert (domain->special_static_fields);
+			mono_domain_lock (domain);
+			addr = g_hash_table_lookup (domain->special_static_fields, field);
+			mono_domain_unlock (domain);
+			g_assert (addr);
+			return (guint8*)addr + 1;
+		}
+
 		/* The value is offset by 1 */
 		if (m_class_is_valuetype (field->parent) && !(field->type->attrs & FIELD_ATTRIBUTE_STATIC))
 			return GUINT_TO_POINTER (field->offset - MONO_ABI_SIZEOF (MonoObject) + 1);
-- 
2.7.4