From ff05128a8748e0336c9da3dd38a99649ce43c301 Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Fri, 15 Sep 2023 18:22:37 +0200
Subject: [PATCH] Add atomic_fetch_exchange builtin.

---
 src/compiler/compiler_internal.h     | 18 ++++++++++++++++++
 src/compiler/enums.h                 |  1 +
 src/compiler/llvm_codegen_builtins.c |  4 ++++
 src/compiler/sema_builtins.c         | 24 ++++++++++++++++++++++++
 src/compiler/symtab.c                |  1 +
 src/version.h                        |  2 +-
 6 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/src/compiler/compiler_internal.h b/src/compiler/compiler_internal.h
index 063e5b0b8..dcd3b7559 100644
--- a/src/compiler/compiler_internal.h
+++ b/src/compiler/compiler_internal.h
@@ -2663,6 +2663,24 @@ INLINE bool type_is_pointer_vector(Type *type)
 	return type->type_kind == TYPE_VECTOR && type->array.base->canonical->type_kind == TYPE_POINTER;
 }
 
+INLINE bool type_is_atomic(Type *type_flat)
+{
+	switch (type_flat->type_kind)
+	{
+		case ALL_UNSIGNED_INTS:
+		case ALL_SIGNED_INTS:
+		case ALL_FLOATS:
+		case TYPE_ENUM:
+		case TYPE_FAULTTYPE:
+		case TYPE_ANYFAULT:
+		case TYPE_TYPEID:
+			break;
+		default:
+			return false;
+	}
+	return type_size(type_flat) <= type_size(type_iptr);
+}
+
 INLINE bool type_is_pointer(Type *type)
 {
 	DECL_TYPE_KIND_REAL(kind, type);
diff --git a/src/compiler/enums.h b/src/compiler/enums.h
index bff79f011..96a2081a7 100644
--- a/src/compiler/enums.h
+++ b/src/compiler/enums.h
@@ -841,6 +841,7 @@ typedef enum
 	BUILTIN_ABS,
 	BUILTIN_ATOMIC_LOAD,
 	BUILTIN_ATOMIC_STORE,
+	BUILTIN_ATOMIC_FETCH_EXCHANGE,
 	BUILTIN_ATOMIC_FETCH_ADD,
 	BUILTIN_ATOMIC_FETCH_SUB,
 	BUILTIN_ATOMIC_FETCH_AND,
diff --git a/src/compiler/llvm_codegen_builtins.c b/src/compiler/llvm_codegen_builtins.c
index 217a51242..cf19fa831 100644
--- a/src/compiler/llvm_codegen_builtins.c
+++ b/src/compiler/llvm_codegen_builtins.c
@@ -192,6 +192,9 @@ INLINE void llvm_emit_atomic_fetch(GenContext *c, BuiltinFunction func, BEValue
 	static LLVMAtomicRMWBinOp LLVMAtomicRMWBinOpUDecWrap = LLVMAtomicRMWBinOpFMin + 2;
 	switch (func)
 	{
+		case BUILTIN_ATOMIC_FETCH_EXCHANGE:
+			op = LLVMAtomicRMWBinOpXchg;
+			break;
 		case BUILTIN_ATOMIC_FETCH_ADD:
 			op = is_float ? LLVMAtomicRMWBinOpFAdd : LLVMAtomicRMWBinOpAdd;
 			break;
@@ -815,6 +818,7 @@ void llvm_emit_builtin_call(GenContext *c, BEValue *result_value, Expr *expr)
 		case BUILTIN_ATOMIC_FETCH_MIN:
 		case BUILTIN_ATOMIC_FETCH_SUB:
 		case BUILTIN_ATOMIC_FETCH_DEC_WRAP:
+		case BUILTIN_ATOMIC_FETCH_EXCHANGE:
 			llvm_emit_atomic_fetch(c, func, result_value, expr);
 			return;
 		case BUILTIN_ATOMIC_LOAD:
diff --git a/src/compiler/sema_builtins.c b/src/compiler/sema_builtins.c
index ac958049a..0def5c4a9 100644
--- a/src/compiler/sema_builtins.c
+++ b/src/compiler/sema_builtins.c
@@ -779,6 +779,29 @@ bool sema_expr_analyse_builtin_call(SemaContext *context, Expr *expr)
 			rtype = args[1]->type;
 			break;
 		}
+		case BUILTIN_ATOMIC_FETCH_EXCHANGE:
+		{
+			assert(arg_count == 5);
+			if (!sema_check_builtin_args(args, (BuiltinArg[]) { BA_POINTER }, 1)) return false;
+			Type *original = type_flatten(args[0]->type);
+			if (original != type_voidptr)
+			{
+				if (!cast_implicit(context, args[1], original->pointer)) return false;
+			}
+			Type *val = type_flatten(args[1]->type);
+			if (!type_is_atomic(val)) RETURN_SEMA_ERROR(args[1], "%s exceeds pointer size.", val);
+			if (!expr_is_const(args[2])) RETURN_SEMA_ERROR(args[2], "'is_volatile' must be a compile time constant.");
+			if (!expr_is_const(args[3])) RETURN_SEMA_ERROR(args[3], "Ordering must be a compile time constant.");
+			if (!is_valid_atomicity(args[3])) return false;
+			switch (args[3]->const_expr.ixx.i.low)
+			{
+				case ATOMIC_UNORDERED:
+					RETURN_SEMA_ERROR(args[3], "'unordered' is not valid ordering.");
+			}
+			if (!sema_check_alignment_expression(context, args[4])) return false;
+			rtype = args[1]->type;
+			break;
+		}
 		case BUILTIN_ATOMIC_FETCH_ADD:
 		case BUILTIN_ATOMIC_FETCH_SUB:
 		case BUILTIN_ATOMIC_FETCH_MAX:
@@ -939,6 +962,7 @@ static inline int builtin_expected_args(BuiltinFunction func)
 		case BUILTIN_GATHER:
 		case BUILTIN_SCATTER:
 			return 4;
+		case BUILTIN_ATOMIC_FETCH_EXCHANGE:
 		case BUILTIN_ATOMIC_FETCH_ADD:
 		case BUILTIN_ATOMIC_FETCH_INC_WRAP:
 		case BUILTIN_ATOMIC_FETCH_NAND:
diff --git a/src/compiler/symtab.c b/src/compiler/symtab.c
index 417770f20..7c478df95 100644
--- a/src/compiler/symtab.c
+++ b/src/compiler/symtab.c
@@ -200,6 +200,7 @@ void symtab_init(uint32_t capacity)
 	builtin_list[BUILTIN_ATOMIC_LOAD] = KW_DEF("atomic_load");
 	builtin_list[BUILTIN_ATOMIC_STORE] = KW_DEF("atomic_store");
 	builtin_list[BUILTIN_ATOMIC_FETCH_ADD] = KW_DEF("atomic_fetch_add");
+	builtin_list[BUILTIN_ATOMIC_FETCH_EXCHANGE] = KW_DEF("atomic_fetch_exchange");
 	builtin_list[BUILTIN_ATOMIC_FETCH_SUB] = KW_DEF("atomic_fetch_sub");
 	builtin_list[BUILTIN_ATOMIC_FETCH_MAX] = KW_DEF("atomic_fetch_max");
 	builtin_list[BUILTIN_ATOMIC_FETCH_MIN] = KW_DEF("atomic_fetch_min");
diff --git a/src/version.h b/src/version.h
index f82b0e51a..6c85acc93 100644
--- a/src/version.h
+++ b/src/version.h
@@ -1 +1 @@
-#define COMPILER_VERSION "0.4.647"
\ No newline at end of file
+#define COMPILER_VERSION "0.4.648"
\ No newline at end of file