fixes, add_sp instruciton and translation of br instruction from wasm

10 files changed, 450 insertions, 220 deletions

diff --git a/design/stack_machine.v b/design/stack_machine.v
index 5e6e0d6..b5c56e6 100644
--- a/design/stack_machine.v
+++ b/design/stack_machine.v
@@ -201,6 +201,10 @@ module stack_machine_new
    assign instr_jump = use_im && stack_same_size &&
 		       instruction[11:7] == 5'd1;
 
+   wire 	      instr_add_sp;
+   assign instr_add_sp = use_im && stack_same_size &&
+			 instruction[11:7] == 5'd2;
+
    /* Instructions, that grow stack */
    wire 	      instr_tee;
    assign instr_tee = !set_im && !use_im && stack_grows &&
@@ -533,6 +537,9 @@ module stack_machine_new
 	      if (instr_set_sp)
 		`SET_SP(im_effective);
 
+	      if (instr_add_sp)
+		`SET_SP(im_effective + sp);
+
 	      if (instr_jump)
 		`SET_PC(im_effective);
 
diff --git a/tclasm.tcl b/tclasm.tcl
index 000f2ca..6a97b1f 100755
--- a/tclasm.tcl
+++ b/tclasm.tcl
@@ -266,6 +266,15 @@ proc jump {address} {
 }
 
 
+proc _add_sp {number_part} {
+    puts 010000010[__to_binary $number_part 7]
+}
+
+proc add_sp {number} {
+    _with_im _add_sp $number
+}
+
+
 # Instructions, that grow stack
 
 proc tee {} {
diff --git a/tests/wasm_compile_br/Makefile b/tests/wasm_compile_br/Makefile
new file mode 120000
index 0000000..e451c8b
--- /dev/null
+++ b/tests/wasm_compile_br/Makefile
@@ -0,0 +1 @@
+../wasm_compile_simple_module/Makefile
\ No newline at end of file
diff --git a/tests/wasm_compile_br/instructions.wat b/tests/wasm_compile_br/instructions.wat
new file mode 100644
index 0000000..cc7b370
--- /dev/null
+++ b/tests/wasm_compile_br/instructions.wat
@@ -0,0 +1,23 @@
+;;; this test is based on wasm_compile_if_else
+(module
+ (memory 0 2)
+ (func $eq10 (param $x i32) (result i32)
+       (if (result i32)
+	   (i32.sub
+	    (get_local $x)
+	    (i32.const 10))
+	 (then
+	  (br 1 (i32.add (i32.const -3) (i32.const 3)))
+	  ;; unreachable instruction
+	  ;; (i32.const 5)
+	  )
+	 (else
+	  (i32.const -1))))
+ (func $main
+       ;; write 0x00000000 at MEMORY_BOTTOM_ADDR
+       (i32.store offset=0x0 align=2 (i32.const 0x0)
+		  (call $eq10 (i32.const 12)))
+       ;; write 0xFFFFFFFF at MEMORY_BOTTOM_ADDR + 0x4
+       (i32.store offset=0x0 align=2 (i32.const 0x4)
+		  (call $eq10 (i32.const 10))))
+ (export "main" (func $main)))
diff --git a/tests/wasm_compile_br/test.v b/tests/wasm_compile_br/test.v
new file mode 120000
index 0000000..f0235d8
--- /dev/null
+++ b/tests/wasm_compile_br/test.v
@@ -0,0 +1 @@
+../wasm_compile_simple_module/test.v
\ No newline at end of file
diff --git a/tests/wasm_compile_br/words_to_verify.mem b/tests/wasm_compile_br/words_to_verify.mem
new file mode 120000
index 0000000..8e12d5b
--- /dev/null
+++ b/tests/wasm_compile_br/words_to_verify.mem
@@ -0,0 +1 @@
+../wasm_compile_if_else/words_to_verify.mem
\ No newline at end of file
diff --git a/tools/stack_machine_instruction.h b/tools/stack_machine_instruction.h
index ea65334..003fa19 100644
--- a/tools/stack_machine_instruction.h
+++ b/tools/stack_machine_instruction.h
@@ -146,6 +146,7 @@ Y(nop,         0x0001) /* 0000_0000_0000_0001 */
 Y(swap,        0x0002) /* 0000_0000_0000_0010 */
 X(set_sp,      0x4000) /* 0100_0000_0xxx_xxxx */
 X(jump,        0x4080) /* 0100_0000_1xxx_xxxx */
+X(add_sp,      0x4100) /* 0100_0001_0xxx_xxxx */
 Y(tee,         0x1000) /* 0001_0000_0000_0000 */
 Y(get_frame,   0x1001) /* 0001_0000_0000_0001 */
 X(const,       0x5000) /* 0101_0000_0xxx_xxxx */
diff --git a/tools/translate.c b/tools/translate.c
index 3a4496d..64ed407 100644
--- a/tools/translate.c
+++ b/tools/translate.c
@@ -7,6 +7,13 @@ struct target {
 	struct target *prev;
 };
 
+struct label {
+	struct label *prev;
+	struct target *target;
+	struct resulttype *arity;
+	uint32_t values_on_stack;
+};
+
 struct types {
 	struct types *prev;
 	char type; /* should be one of VALTYPE_* constants from wasm.h */
@@ -18,6 +25,7 @@ struct translation {
 	struct function *function;
 	struct module *module;
 	struct types *types_stack;
+	struct label *labels;
 };
 
 struct end_markers {
@@ -53,6 +61,18 @@ static void put_type(struct types *type)
 	}
 }
 
+static uint32_t stack_size(struct types *types_stack)
+{
+	uint32_t count = 0;
+
+	while (types_stack) {
+		count++;
+		types_stack = types_stack->prev;
+	}
+
+	return count;
+}
+
 static void free_types_stack(struct types *top)
 {
 	struct types *tmp;
@@ -67,94 +87,196 @@ static void free_types_stack(struct types *top)
 static int translate_expr(struct translation *data, struct resulttype *args,
 			  struct resulttype *results,
 			  const struct end_markers *end_markers,
-			  char *marker_found);
+			  char *marker_found, bool continuation_at_start);
+
+static struct target *add_target(struct module *module);
+
+static int parse_blocktype(FILE *handle, struct resulttype *args,
+			   struct resulttype *results, char *storage,
+			   struct module *module);
 
 /* All functions, that go into one of function pointer arrays, start with _ */
 
-/** DEFINE INSTRUCTION TRANSLATION FUNCTIONS **/
+/** DEFINE ARGUMENT TYPECHECK FUNCTIONS **/
 
-/* Translate complex - those routines have to be defined manually */
-#define TC(wasm_opcode, name, argtypes, restype)
+static int _argcheck_empty(struct types **types_stack)
+{
+	return 0;
+}
 
-static int parse_blocktype(FILE *handle, struct resulttype *args,
-			   struct resulttype *results, char *storage,
-			   struct module *module)
+static int argcheck_generic_noremove(struct types *types_stack, char expected)
 {
-	int readval;
-	uint32_t typeidx;
+	char *name;
 
-	readval = fgetc(handle);
+	name =
+		expected == VALTYPE_F64 ? "f64" :
+		expected == VALTYPE_F32 ? "f32" :
+		expected == VALTYPE_I64 ? "i64" :
+		"i32";
 
-	if (readval == EOF) {
-		PRERR(MSG_EOF);
+	if (!types_stack) {
+		PRERR("Expected %s on stack, got nothing\n", name);
 		return -1;
 	}
 
-	if (readval == 0x40) {
-		/* Blocktype is empty (no arguments, no result values) */
-		*args = (struct resulttype) {.count = 0, .types = NULL};
-		*results = *args;
-		return 0;
+	if (types_stack->type != VALTYPE_I32) {
+		PRERR("Expected %s (0x%02hhx) on stack, got 0x%02hhx\n",
+		      name, expected, types_stack->type);
+		return -1;
 	}
 
-	/*
-	 * A nonnegative array index encoded as signed number in LEB
-	 * shall have 0 as the second (most significant) bit of the first byte.
-	 * Otherwise, it can't be array index, but might be a simple value type.
-	 */
-	if (readval & (1 << 6)) {
-		if (!is_valid_valtype(readval))
-			goto fail;
+	return 0;
+}
 
-		*args = (struct resulttype) {.count = 0, .types = NULL};
-		*storage = readval;
-		*results = (struct resulttype) {.count = 1, .types = storage};
-		return 0;
-	}
+static int argcheck_generic(struct types **types_stack, char expected)
+{
+	struct types *top_type;
 
-	/*
-	 * We know for sure it's a nonnegative number, we can just use leb_u32
-	 * decoding function (encoding as signed or unsigned is the same in this
-	 * particular case).
-	 */
-	ungetc(readval, handle);
+	if (argcheck_generic_noremove(*types_stack, expected))
+		return -1;
 
-	if (leb_u32(handle, &typeidx)) {
-		PRERR(MSG_BAD_NUM);
-		goto fail;
+	top_type = *types_stack;
+	*types_stack = top_type->prev;
+
+	if (*types_stack)
+		get_type(*types_stack);
+
+	put_type(top_type);
+
+	return 0;
+}
+
+static int _argcheck_i32(struct types **types_stack)
+{
+	return argcheck_generic(types_stack, VALTYPE_I32);
+}
+
+static int _argcheck_i32_i32(struct types **types_stack)
+{
+	int i;
+
+	for (i = 0; i < 2; i++) {
+		if (argcheck_generic(types_stack, VALTYPE_I32))
+			return -1;
 	}
 
-	if (typeidx <= module->functypes_count) {
-		PRERR(MSG_BAD_IDX("type index"));
-		goto fail;
+	return 0;
+}
+
+static int _argcheck_custom(struct types **types_stack)
+{
+	return 0; /* Translation function will handle argument checks */
+}
+
+/** DEFINE RESULT TYPECHECK FUNCTIONS **/
+
+static int _rescheck_empty(struct types **types_stack)
+{
+	return 0;
+}
+
+static int rescheck_generic(struct types **types_stack, char returned)
+{
+	struct types *top;
+
+	top = malloc(sizeof(struct types));
+
+	if (!top) {
+		PRERR(MSG_ALLOC_FAIL(sizeof(struct types)));
+		return -1;
 	}
 
-	*args = module->functypes[typeidx].args;
-	*results = module->functypes[typeidx].results;
+	*top = (struct types) {.prev = *types_stack, .type = returned, .refs = 1};
+	*types_stack = top;
+
 	return 0;
+}
 
-fail:
-	PRERR("Couldn't parse blocktype\n");
-	return -1;
+static int _rescheck_i32(struct types **types_stack)
+{
+	return rescheck_generic(types_stack, VALTYPE_I32);
 }
 
-static struct target *add_target(struct module *module)
+static int _rescheck_custom(struct types **types_stack)
 {
-	struct target *tgt;
+	return 0;
+}
 
-	tgt = malloc(sizeof(struct target));
+/** DEFINE TYPECHECK FUNCTION POINTER ARRAY **/
 
-	if (!tgt) {
-		PRERR(MSG_ALLOC_FAIL(sizeof(struct target)));
-		return NULL;
+/* Translate complex */
+#define TC(wasm_opcode, name, argtypes, restype)		\
+	[wasm_opcode] = {.argcheck = _argcheck_##argtypes,	\
+			 .rescheck = _rescheck_##restype},
+
+/* Translate Simple */
+#define TS(wasm_opcode, sm_instr, argtypes, restype)	\
+	TC(wasm_opcode, dummy, argtypes, restype)
+
+/* Translate load/store */
+#define TLS(wasm_opcode, sm_instr, argtypes, restype)	\
+	TC(wasm_opcode, dummy, argtypes, restype)
+
+struct typecheck {
+	int (*argcheck) (struct types **), (*rescheck) (struct types **);
+};
+
+static struct typecheck typecheck_routines[256] = {
+#include "translate_xmacro.h"
+};
+
+#undef TS
+#undef TLS
+#undef TC
+
+/** DEFINE CUSTOM TYPECHECK FUNCTIONS **/
+
+/*
+ * Each of these is called by its respective translate function. In some cases
+ * it was not feasible to move some instruction's typecheck to a separate
+ * function, so there are less functions here than instructions with declared
+ * "custom" typechecking.
+ */
+
+static int typecheck_call(struct translation *data, struct function *callee)
+{
+	uint32_t i;
+
+	i = callee->type->args.count;
+
+	while (i--) {
+		if (argcheck_generic(&data->types_stack,
+				     callee->type->args.types[i]))
+			return -1;
 	}
 
-	tgt->instr = NULL;
-	tgt->prev = module->targets;
-	module->targets = tgt;
-	return tgt;
+	for (i = 0; i < callee->type->results.count; i++) {
+		if (rescheck_generic(&data->types_stack,
+				     callee->type->results.types[i]))
+			return -1;
+	}
+
+	return 0;
 }
 
+static int typecheck_local_get(struct translation *data, uint32_t localidx)
+{
+	uint32_t args_count = data->function->type->args.count;
+	char type = localidx < args_count ?
+		data->function->type->args.types[localidx] :
+		data->function->locals[localidx - args_count];
+
+	if (rescheck_generic(&data->types_stack, type))
+		return -1;
+
+	return 0;
+}
+
+/** DEFINE INSTRUCTION TRANSLATION FUNCTIONS **/
+
+/* Translate complex - those routines have to be defined manually */
+#define TC(wasm_opcode, name, argtypes, restype)
+
 static int _translate_if(struct translation *data)
 {
 	struct types *backed_stack;
@@ -191,7 +313,7 @@ static int _translate_if(struct translation *data)
 	get_type(backed_stack);
 
 	retval = translate_expr(data, &block_args, &block_results,
-				&if_end_markers, &marker_found);
+				&if_end_markers, &marker_found, false);
 
 	put_type(data->types_stack);
 	data->types_stack = backed_stack;
@@ -208,7 +330,7 @@ static int _translate_if(struct translation *data)
 		ungetc(WASM_END, data->handle);
 
 	if (translate_expr(data, &block_args, &block_results,
-			   &else_end_markers, NULL))
+			   &else_end_markers, NULL, false))
 		goto fail;
 
 	else_end->instr = data->function->translated_body->prev;
@@ -221,7 +343,88 @@ fail:
 	return -1;
 }
 
-static int typecheck_call(struct translation *data, struct function *callee);
+static int _translate_br(struct translation *data)
+{
+	uint32_t labelidx, i;
+	struct label *label;
+	uint32_t arity, values_on_stack;
+	uint32_t shift, offset_src, offset_dst;
+	struct instruction **expr = &data->function->translated_body;
+
+	if (leb_u32(data->handle, &labelidx)) {
+		PRERR(MSG_BAD_NUM);
+		goto fail;
+	}
+
+	label = data->labels;
+	i = labelidx;
+
+	while (i--) {
+		label = label->prev;
+
+		if (!label) {
+			PRERR(MSG_BAD_IDX("labelidx"));
+			goto fail;
+		}
+	}
+
+	values_on_stack = stack_size(data->types_stack);
+	arity = label->arity ? label->arity->count : 0;
+
+	if (arity > values_on_stack) {
+		PRERR("Need %lu values on stack to branch, only have %lu\n",
+		      (unsigned long) arity, (unsigned long) values_on_stack);
+		goto fail;
+	}
+
+	i = arity;
+
+	while (i--) {
+		if (argcheck_generic(&data->types_stack,
+				     label->arity->types[i]))
+			goto fail;
+	}
+
+	shift = data->labels->values_on_stack + values_on_stack -
+		(label->values_on_stack + arity);
+	offset_dst = label->values_on_stack + 2;
+	offset_src = offset_dst + shift;
+
+	if (!shift)
+		goto values_moved;
+
+	if (i_load  (im(STACK_FRAME_BACKUP_ADDR), expr) ||
+	    i_tee   (                             expr) ||
+	    i_load_p(im(-4 * (offset_dst - 1)),   expr) ||
+	    i_swap  (                             expr) ||
+	    i_load_p(im(-4 * offset_dst),         expr) ||
+	    i_add_sp(im(-4 * (shift + 2)),        expr))
+		goto fail;
+
+	for (i = 0; i < arity; i++) {
+		if (i == 0 && i_load(im(STACK_FRAME_BACKUP_ADDR), expr))
+			goto fail;
+
+		if (i + 1 != arity && (i_tee(expr)))
+			goto fail;
+
+		if (i_load_p(im(-4 * (offset_src + i)), expr))
+			goto fail;
+
+		if (i + 1 != arity && (i_swap(expr)))
+			goto fail;
+	}
+
+values_moved:
+	if (i_jump(ptr_after(&label->target->instr), expr))
+		goto fail;
+
+	return 0;
+
+fail:
+	PRERR("Couldn't translate br instruction\n");
+	return -1;
+}
 
 static int _translate_call(struct translation *data)
 {
@@ -358,210 +561,162 @@ static int (*translation_routines[256]) (struct translation *) = {
 #undef TLS
 #undef TC
 
-/** DEFINE ARGUMENT TYPECHECK FUNCTIONS **/
-
-static int _argcheck_empty(struct types **types_stack)
-{
-	return 0;
-}
+/** REST OF THE CODE **/
 
-static int argcheck_generic_noremove(struct types *types_stack, char expected)
+static int translate_instr(struct translation *data, uint8_t wasm_opcode)
 {
-	char *name;
-
-	name =
-		expected == VALTYPE_F64 ? "f64" :
-		expected == VALTYPE_F32 ? "f32" :
-		expected == VALTYPE_I64 ? "i64" :
-		"i32";
-
-	if (!types_stack) {
-		PRERR("Expected %s on stack, got nothing\n", name);
-		return -1;
-	}
+	struct typecheck *tc_routines;
 
-	if (types_stack->type != VALTYPE_I32) {
-		PRERR("Expected %s (0x%02hhx) on stack, got 0x%02hhx\n",
-		      name, expected, types_stack->type);
+	if (!translation_routines[wasm_opcode]) {
+		PRERR("Unknown Wasm opcode: 0x%02x\n", wasm_opcode);
 		return -1;
 	}
 
-	return 0;
-}
-
-static int argcheck_generic(struct types **types_stack, char expected)
-{
-	struct types *top_type;
+	tc_routines = typecheck_routines + wasm_opcode;
 
-	if (argcheck_generic_noremove(*types_stack, expected))
+	if (tc_routines->argcheck(&data->types_stack) ||
+	    tc_routines->rescheck(&data->types_stack) ||
+	    translation_routines[wasm_opcode](data))
 		return -1;
 
-	top_type = *types_stack;
-	*types_stack = top_type->prev;
-
-	if (*types_stack)
-		get_type(*types_stack);
-
-	put_type(top_type);
-
 	return 0;
 }
 
-static int _argcheck_i32(struct types **types_stack)
+static int parse_blocktype(FILE *handle, struct resulttype *args,
+			   struct resulttype *results, char *storage,
+			   struct module *module)
 {
-	return argcheck_generic(types_stack, VALTYPE_I32);
-}
+	int readval;
+	uint32_t typeidx;
 
-static int _argcheck_i32_i32(struct types **types_stack)
-{
-	int i;
+	readval = fgetc(handle);
 
-	for (i = 0; i < 2; i++) {
-		if (argcheck_generic(types_stack, VALTYPE_I32))
-			return -1;
+	if (readval == EOF) {
+		PRERR(MSG_EOF);
+		return -1;
 	}
 
-	return 0;
-}
-
-static int _argcheck_custom(struct types **types_stack)
-{
-	return 0; /* Translation function will handle argument checks */
-}
-
-/** DEFINE RESULT TYPECHECK FUNCTIONS **/
+	if (readval == 0x40) {
+		/* Blocktype is empty (no arguments, no result values) */
+		*args = (struct resulttype) {.count = 0, .types = NULL};
+		*results = *args;
+		return 0;
+	}
 
-static int _rescheck_empty(struct types **types_stack)
-{
-	return 0;
-}
+	/*
+	 * A nonnegative array index encoded as signed number in LEB
+	 * shall have 0 as the second (most significant) bit of the first byte.
+	 * Otherwise, it can't be array index, but might be a simple value type.
+	 */
+	if (readval & (1 << 6)) {
+		if (!is_valid_valtype(readval))
+			goto fail;
 
-static int rescheck_generic(struct types **types_stack, char returned)
-{
-	struct types *top;
+		*args = (struct resulttype) {.count = 0, .types = NULL};
+		*storage = readval;
+		*results = (struct resulttype) {.count = 1, .types = storage};
+		return 0;
+	}
 
-	top = malloc(sizeof(struct types));
+	/*
+	 * We know for sure it's a nonnegative number, we can just use leb_u32
+	 * decoding function (encoding as signed or unsigned is the same in this
+	 * particular case).
+	 */
+	ungetc(readval, handle);
 
-	if (!top) {
-		PRERR(MSG_ALLOC_FAIL(sizeof(struct types)));
-		return -1;
+	if (leb_u32(handle, &typeidx)) {
+		PRERR(MSG_BAD_NUM);
+		goto fail;
 	}
 
-	*top = (struct types) {.prev = *types_stack, .type = returned, .refs = 1};
-	*types_stack = top;
+	if (typeidx <= module->functypes_count) {
+		PRERR(MSG_BAD_IDX("type index"));
+		goto fail;
+	}
 
+	*args = module->functypes[typeidx].args;
+	*results = module->functypes[typeidx].results;
 	return 0;
-}
-
-static int _rescheck_i32(struct types **types_stack)
-{
-	return rescheck_generic(types_stack, VALTYPE_I32);
-}
 
-static int _rescheck_custom(struct types **types_stack)
-{
-	return 0;
+fail:
+	PRERR("Couldn't parse blocktype\n");
+	return -1;
 }
 
-/** DEFINE TYPECHECK FUNCTION POINTER ARRAY **/
-
-/* Translate complex */
-#define TC(wasm_opcode, name, argtypes, restype)		\
-	[wasm_opcode] = {.argcheck = _argcheck_##argtypes,	\
-			 .rescheck = _rescheck_##restype},
-
-/* Translate Simple */
-#define TS(wasm_opcode, sm_instr, argtypes, restype)	\
-	TC(wasm_opcode, dummy, argtypes, restype)
-
-/* Translate load/store */
-#define TLS(wasm_opcode, sm_instr, argtypes, restype)	\
-	TC(wasm_opcode, dummy, argtypes, restype)
-
-struct typecheck {
-	int (*argcheck) (struct types **), (*rescheck) (struct types **);
-};
-
-static struct typecheck typecheck_routines[256] = {
-#include "translate_xmacro.h"
-};
-
-#undef TS
-#undef TLS
-#undef TC
-
-/** DEFINE CUSTOM TYPECHECK FUNCTIONS **/
-
-static int typecheck_call(struct translation *data, struct function *callee)
+static struct target *add_target(struct module *module)
 {
-	uint32_t i;
-
-	i = callee->type->args.count;
+	struct target *tgt;
 
-	while (i--) {
-		if (argcheck_generic(&data->types_stack,
-				     callee->type->args.types[i]))
-			return -1;
-	}
+	tgt = malloc(sizeof(struct target));
 
-	for (i = 0; i < callee->type->results.count; i++) {
-		if (rescheck_generic(&data->types_stack,
-				     callee->type->results.types[i]))
-			return -1;
+	if (!tgt) {
+		PRERR(MSG_ALLOC_FAIL(sizeof(struct target)));
+		return NULL;
 	}
 
-	return 0;
+	tgt->instr = NULL;
+	tgt->prev = module->targets;
+	module->targets = tgt;
+	return tgt;
 }
 
-static int typecheck_local_get(struct translation *data, uint32_t localidx)
+static struct label *add_label(struct translation *data, struct target *target,
+			       struct resulttype *arity)
 {
-	uint32_t args_count = data->function->type->args.count;
-	char type = localidx < args_count ?
-		data->function->type->args.types[localidx] :
-		data->function->locals[localidx - args_count];
+	struct label *lbl;
 
-	if (rescheck_generic(&data->types_stack, type))
-		return -1;
+	lbl = malloc(sizeof(struct label));
 
-	return 0;
-}
-
-/** REST OF THE CODE **/
-
-static int translate_instr(struct translation *data, uint8_t wasm_opcode)
-{
-	struct typecheck *tc_routines;
-
-	if (!translation_routines[wasm_opcode]) {
-		PRERR("Unknown Wasm opcode: 0x%02x\n", wasm_opcode);
-		return -1;
+	if (!lbl) {
+		PRERR(MSG_ALLOC_FAIL(sizeof(struct label)));
+		return NULL;
 	}
 
-	tc_routines = typecheck_routines + wasm_opcode;
+	lbl->prev = data->labels;
+	lbl->target = target;
+	lbl->arity = arity;
+	lbl->values_on_stack = data->labels ? data->labels->values_on_stack : 0;
+	lbl->values_on_stack += stack_size(data->types_stack);
 
-	if (tc_routines->argcheck(&data->types_stack) ||
-	    tc_routines->rescheck(&data->types_stack) ||
-	    translation_routines[wasm_opcode](data))
-		return -1;
+	data->labels = lbl;
 
-	return 0;
+	return lbl;
 }
 
 static int translate_expr(struct translation *data, struct resulttype *args,
 			  struct resulttype *results,
 			  const struct end_markers *end_markers,
-			  char *marker_found)
+			  char *marker_found, bool continuation_at_start)
 {
-	struct types **tmp, *types_stack_rest;
-	uint32_t i;
+	struct target *continuation;
+	struct label *label = NULL;
+	struct types **tmp, *types_stack_rest = NULL;
+	uint32_t i, rescount = results ? results->count : 0;
 	int wasm_opcode;
+	bool last_instruction_was_branch = false;
+	int retval = -1;
+
+	continuation = add_target(data->module);
+
+	if (!continuation)
+		goto fail;
+
+	if (continuation_at_start)
+		continuation->instr = data->function->translated_body->prev;
+
+	label = add_label(data, continuation,
+			  continuation_at_start ? args : results);
+
+	if (!label)
+		goto fail;
 
 	tmp = &data->types_stack;
 	i = args ? args->count : 0;
 
 	while (i--) {
 		if (argcheck_generic_noremove(*tmp, args->types[i]))
-			return -1;
+			goto fail;
 
 		tmp = &(*tmp)->prev;
 	}
@@ -580,19 +735,40 @@ static int translate_expr(struct translation *data, struct resulttype *args,
 		i = end_markers->count;
 
 		while (i--) {
-			if (wasm_opcode == end_markers->codes[i]) {
-				if (marker_found)
-					*marker_found = wasm_opcode;
-
+			if (wasm_opcode == end_markers->codes[i])
 				goto block_end;
-			}
 		}
 
 		if (translate_instr(data, wasm_opcode))
 			goto fail;
+
+		/* WASM_BR_TABLE will also appear here once implemented */
+		last_instruction_was_branch =
+			wasm_opcode == WASM_BR;
 	}
 
 block_end:
+	if (marker_found)
+		*marker_found = wasm_opcode;
+
+	if (!continuation_at_start)
+		continuation->instr = data->function->translated_body->prev;
+
+	/*
+	 * Types on stack don't seem to matter, if last instruction was an
+	 * unconditional branch anyway. However, we need to make the types stack
+	 * appear ok to our caller.
+	 */
+	if (last_instruction_was_branch) {
+		put_type(data->types_stack);
+		data->types_stack = NULL;
+
+		for (i = 0; i < rescount; i++) {
+			if (rescheck_generic(&data->types_stack,
+					     results->types[i]))
+				goto fail;
+		}
+	}
 
 	tmp = &data->types_stack;
 	i = results ? results->count : 0;
@@ -610,13 +786,21 @@ block_end:
 	}
 
 	*tmp = types_stack_rest;
-	return 0;
+	types_stack_rest = NULL;
+	retval = 0;
 
 fail:
-	put_type(data->types_stack);
-	data->types_stack = types_stack_rest;
+	if (label) {
+		data->labels = label->prev;
+		free(label);
+	}
 
-	return -1;
+	if (types_stack_rest) {
+		put_type(data->types_stack);
+		data->types_stack = types_stack_rest;
+	}
+
+	return retval;
 }
 
 int translate(FILE *handle, struct function *function, struct module *module)
@@ -634,7 +818,8 @@ int translate(FILE *handle, struct function *function, struct module *module)
 	struct translation data = {.handle = handle,
 				   .function = function,
 				   .module = module,
-				   .types_stack = NULL};
+				   .types_stack = NULL,
+				   .labels = NULL};
 	int retval = -1;
 
 	if (locals_count + (uint64_t) args_count > STACK_TOP_ADDR * 4) {
@@ -657,7 +842,7 @@ int translate(FILE *handle, struct function *function, struct module *module)
 
 	/* actual function body */
 	if (translate_expr(&data, NULL, &function->type->results,
-			   &function_end_markers, NULL))
+			   &function_end_markers, NULL, false))
 		goto fail;
 
         /* function epilogue */
diff --git a/tools/translate_xmacro.h b/tools/translate_xmacro.h
index b271e75..f68f317 100644
--- a/tools/translate_xmacro.h
+++ b/tools/translate_xmacro.h
@@ -20,6 +20,7 @@ TLS(WASM_I32_STORE16,  storew_p,            i32_i32,        empty)
  * another way and only check for the i32 condition value here.
  */
 TC (WASM_IF,           if,                  i32,            custom)
+TC (WASM_BR,           br,                  custom,         custom)
 TC (WASM_CALL,         call,                custom,         custom)
 TC (WASM_LOCAL_GET,    local_get,           empty,          custom)
 TC (WASM_I32_CONST,    const,               empty,          i32)
diff --git a/tools/wasm.h b/tools/wasm.h
index bf85490..0c36c11 100644
--- a/tools/wasm.h
+++ b/tools/wasm.h
@@ -25,6 +25,7 @@
 #define WASM_IF            0x04
 #define WASM_ELSE          0x05
 #define WASM_END           0x0B
+#define WASM_BR            0x0C
 #define WASM_CALL          0x10
 
 #define WASM_LOCAL_GET     0x20