[interp] Small interp tweaks (#48412)

* [interp] Fix overflow in PROFILE_INTERP log

* [interp] Replace LDFLDA of offset 0 field with MOV

Commonly used when accessing first field of valuetypes, eg span operations. Will help with cprop and remove redundant instruction.

* [interp] Remove redundant opcode

src/mono/mono/mini/interp/interp.c

@@ -4841,11 +4841,6 @@ call:
 			ip += 4;;
 			MINT_IN_BREAK;
 		}
-		MINT_IN_CASE(MINT_INTRINS_BYREFERENCE_GET_VALUE) {
-			LOCAL_VAR (ip [1], gpointer) = *LOCAL_VAR (ip [2], gpointer*);
-			ip += 3;
-			MINT_IN_BREAK;
-		}
 		MINT_IN_CASE(MINT_INTRINS_UNSAFE_ADD_BYTE_OFFSET) {
 			LOCAL_VAR (ip [1], gpointer) = LOCAL_VAR (ip [2], guint8*) + LOCAL_VAR (ip [3], mono_u);
 			ip += 4;
@@ -7169,7 +7164,13 @@ interp_add_imethod (gpointer method)
 static int
 imethod_opcount_comparer (gconstpointer m1, gconstpointer m2)
 {
-	return (*(InterpMethod**)m2)->opcounts - (*(InterpMethod**)m1)->opcounts;
+	long diff = (*(InterpMethod**)m2)->opcounts > (*(InterpMethod**)m1)->opcounts;
+	if (diff > 0)
+		return 1;
+	else if (diff < 0)
+		return -1;
+	else
+		return 0;
 }
 
 static void

src/mono/mono/mini/interp/mintops.def

@@ -716,7 +716,6 @@ OPDEF(MINT_INTRINS_ENUM_HASFLAG, "intrins_enum_hasflag", 5, 1, 2, MintOpClassTok
 OPDEF(MINT_INTRINS_GET_HASHCODE, "intrins_get_hashcode", 3, 1, 1, MintOpNoArgs)
 OPDEF(MINT_INTRINS_GET_TYPE, "intrins_get_type", 3, 1, 1, MintOpNoArgs)
 OPDEF(MINT_INTRINS_SPAN_CTOR, "intrins_span_ctor", 4, 1, 2, MintOpNoArgs)
-OPDEF(MINT_INTRINS_BYREFERENCE_GET_VALUE, "intrins_byreference_get_value", 3, 1, 1, MintOpNoArgs)
 OPDEF(MINT_INTRINS_UNSAFE_ADD_BYTE_OFFSET, "intrins_unsafe_add_byte_offset", 4, 1, 2, MintOpNoArgs)
 OPDEF(MINT_INTRINS_UNSAFE_BYTE_OFFSET, "intrins_unsafe_byte_offset", 4, 1, 2, MintOpNoArgs)
 OPDEF(MINT_INTRINS_RUNTIMEHELPERS_OBJECT_HAS_COMPONENT_SIZE, "intrins_runtimehelpers_object_has_component_size", 3, 1, 1, MintOpNoArgs)

src/mono/mono/mini/interp/transform.c

@@ -2026,7 +2026,7 @@ interp_handle_intrinsics (TransformData *td, MonoMethod *target_method, MonoClas
 		*op = MINT_INTRINS_CLEAR_WITH_REFERENCES;
 	} else if (in_corlib && !strcmp (klass_name_space, "System") && !strcmp (klass_name, "ByReference`1")) {
 		g_assert (!strcmp (tm, "get_Value"));
-		*op = MINT_INTRINS_BYREFERENCE_GET_VALUE;
+		*op = MINT_LDIND_I;
 	} else if (in_corlib && !strcmp (klass_name_space, "System") && !strcmp (klass_name, "Marvin")) {
 		if (!strcmp (tm, "Block"))
 			*op = MINT_INTRINS_MARVIN_BLOCK;
@@ -5621,14 +5621,20 @@ generate_code (TransformData *td, MonoMethod *method, MonoMethodHeader *header,
 					goto_if_nok (error, exit);
 				} else {
 					td->sp--;
+					int foffset = m_class_is_valuetype (klass) ? field->offset - MONO_ABI_SIZEOF (MonoObject) : field->offset;
 					if (td->sp->type == STACK_TYPE_O) {
 						interp_add_ins (td, MINT_LDFLDA);
+						td->last_ins->data [0] = foffset;
 					} else {
 						int sp_type = td->sp->type;
 						g_assert (sp_type == STACK_TYPE_MP || sp_type == STACK_TYPE_I);
-						interp_add_ins (td, MINT_LDFLDA_UNSAFE);
+						if (foffset) {
+							interp_add_ins (td, MINT_LDFLDA_UNSAFE);
+							td->last_ins->data [0] = foffset;
+						} else {
+							interp_add_ins (td, MINT_MOV_P);
+						}
 					}
-					td->last_ins->data [0] = m_class_is_valuetype (klass) ? field->offset - MONO_ABI_SIZEOF (MonoObject) : field->offset;
 					interp_ins_set_sreg (td->last_ins, td->sp [0].local);
 					push_simple_type (td, STACK_TYPE_MP);
 					interp_ins_set_dreg (td->last_ins, td->sp [-1].local);