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Merged
shravanrn merged 1 commit into from
Aug 8, 2026
+258 −61
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wasm2c: Optimize call indirect code footprint for better performance #2807

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59 changes: 51 additions & 8 deletions src/prebuilt/wasm2c_source_declarations.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -137,22 +137,65 @@ R"w2c_template(
#define UNREACHABLE TRAP(UNREACHABLE)
)w2c_template"
R"w2c_template(
static inline bool func_types_eq(const wasm_rt_func_type_t a,
#if defined(__clang__) || defined(__GNUC__)
)w2c_template"
R"w2c_template( const wasm_rt_func_type_t b) {
R"w2c_template(#define W2C_COLD_FUNC __attribute__((noinline, cold))
)w2c_template"
R"w2c_template( return (a == b) || LIKELY(a && b && !memcmp(a, b, 32));
R"w2c_template(#elif defined(_MSC_VER)
)w2c_template"
R"w2c_template(}
R"w2c_template(#define W2C_COLD_FUNC __declspec(noinline)
)w2c_template"
R"w2c_template(#else
)w2c_template"
R"w2c_template(#define W2C_COLD_FUNC
)w2c_template"
R"w2c_template(#endif
)w2c_template"
R"w2c_template(
#define CHECK_CALL_INDIRECT(table, ft, x) \
W2C_COLD_FUNC static bool func_types_eq_slowpath(
)w2c_template"
R"w2c_template( const wasm_rt_funcref_table_t* table,
)w2c_template"
R"w2c_template( const wasm_rt_func_type_t expected_type,
)w2c_template"
R"w2c_template( uint32_t index) {
)w2c_template"
R"w2c_template( const size_t sha256size = 32;
)w2c_template"
R"w2c_template( if (index >= table->size) {
)w2c_template"
R"w2c_template( // Table index out of bounds. Raise Wasm trap.
)w2c_template"
R"w2c_template( TRAP(CALL_INDIRECT);
)w2c_template"
R"w2c_template( return false;
)w2c_template"
R"w2c_template( (LIKELY((x) < table.size && table.data[x].func && \
R"w2c_template( }
)w2c_template"
R"w2c_template( const wasm_rt_funcref_t* const func_ref = &table->data[index];
)w2c_template"
R"w2c_template( if (!expected_type || !func_ref->func || !func_ref->func_type ||
)w2c_template"
R"w2c_template( memcmp(expected_type, func_ref->func_type, sha256size) != 0) {
)w2c_template"
R"w2c_template( // Type check failed. Raise Wasm trap.
)w2c_template"
R"w2c_template( TRAP(CALL_INDIRECT);
)w2c_template"
R"w2c_template( return false;
)w2c_template"
R"w2c_template( }
)w2c_template"
R"w2c_template( return true;
)w2c_template"
R"w2c_template(}
)w2c_template"
R"w2c_template(
#define CHECK_CALL_INDIRECT(table, ft, x) \
)w2c_template"
R"w2c_template( func_types_eq(ft, table.data[x].func_type)) || \
R"w2c_template( (LIKELY((x) < table.size && ft == table.data[x].func_type) || \
)w2c_template"
R"w2c_template( TRAP(CALL_INDIRECT))
R"w2c_template( func_types_eq_slowpath(&(table), ft, x))
)w2c_template"
R"w2c_template(
#define DO_CALL_INDIRECT(table, t, x, ...) ((t)table.data[x].func)(__VA_ARGS__)
Expand Down
36 changes: 29 additions & 7 deletions src/template/wasm2c.declarations.c
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Original file line number Diff line number Diff line change
Expand Up @@ -73,15 +73,37 @@ static inline void wasm_rt_segue_write_base(void* base) {

#define UNREACHABLE TRAP(UNREACHABLE)

static inline bool func_types_eq(const wasm_rt_func_type_t a,
const wasm_rt_func_type_t b) {
return (a == b) || LIKELY(a && b && !memcmp(a, b, 32));
#if defined(__clang__) || defined(__GNUC__)
#define W2C_COLD_FUNC __attribute__((noinline, cold))
#elif defined(_MSC_VER)
#define W2C_COLD_FUNC __declspec(noinline)
#else
#define W2C_COLD_FUNC
#endif

W2C_COLD_FUNC static bool func_types_eq_slowpath(
const wasm_rt_funcref_table_t* table,
const wasm_rt_func_type_t expected_type,
uint32_t index) {
const size_t sha256size = 32;
if (index >= table->size) {
// Table index out of bounds. Raise Wasm trap.
TRAP(CALL_INDIRECT);
return false;
}
const wasm_rt_funcref_t* const func_ref = &table->data[index];
if (!expected_type || !func_ref->func || !func_ref->func_type ||
memcmp(expected_type, func_ref->func_type, sha256size) != 0) {
// Type check failed. Raise Wasm trap.
TRAP(CALL_INDIRECT);
return false;
}
return true;
}

#define CHECK_CALL_INDIRECT(table, ft, x) \
(LIKELY((x) < table.size && table.data[x].func && \
func_types_eq(ft, table.data[x].func_type)) || \
TRAP(CALL_INDIRECT))
#define CHECK_CALL_INDIRECT(table, ft, x) \
(LIKELY((x) < table.size && ft == table.data[x].func_type) || \
func_types_eq_slowpath(&(table), ft, x))

#define DO_CALL_INDIRECT(table, t, x, ...) ((t)table.data[x].func)(__VA_ARGS__)

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38 changes: 30 additions & 8 deletions test/wasm2c/add.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -140,15 +140,37 @@ static inline void wasm_rt_segue_write_base(void* base) {

#define UNREACHABLE TRAP(UNREACHABLE)

static inline bool func_types_eq(const wasm_rt_func_type_t a,
const wasm_rt_func_type_t b) {
return (a == b) || LIKELY(a && b && !memcmp(a, b, 32));
}
#if defined(__clang__) || defined(__GNUC__)
#define W2C_COLD_FUNC __attribute__((noinline, cold))
#elif defined(_MSC_VER)
#define W2C_COLD_FUNC __declspec(noinline)
#else
#define W2C_COLD_FUNC
#endif

#define CHECK_CALL_INDIRECT(table, ft, x) \
(LIKELY((x) < table.size && table.data[x].func && \
func_types_eq(ft, table.data[x].func_type)) || \
TRAP(CALL_INDIRECT))
W2C_COLD_FUNC static bool func_types_eq_slowpath(
const wasm_rt_funcref_table_t* table,
const wasm_rt_func_type_t expected_type,
uint32_t index) {
const size_t sha256size = 32;
if (index >= table->size) {
// Table index out of bounds. Raise Wasm trap.
TRAP(CALL_INDIRECT);
return false;
}
const wasm_rt_funcref_t* const func_ref = &table->data[index];
if (!expected_type || !func_ref->func || !func_ref->func_type ||
memcmp(expected_type, func_ref->func_type, sha256size) != 0) {
// Type check failed. Raise Wasm trap.
TRAP(CALL_INDIRECT);
return false;
}
return true;
}

#define CHECK_CALL_INDIRECT(table, ft, x) \
(LIKELY((x) < table.size && ft == table.data[x].func_type) || \
func_types_eq_slowpath(&(table), ft, x))

#define DO_CALL_INDIRECT(table, t, x, ...) ((t)table.data[x].func)(__VA_ARGS__)

Expand Down
38 changes: 30 additions & 8 deletions test/wasm2c/check-imports.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -165,15 +165,37 @@ static inline void wasm_rt_segue_write_base(void* base) {

#define UNREACHABLE TRAP(UNREACHABLE)

static inline bool func_types_eq(const wasm_rt_func_type_t a,
const wasm_rt_func_type_t b) {
return (a == b) || LIKELY(a && b && !memcmp(a, b, 32));
}
#if defined(__clang__) || defined(__GNUC__)
#define W2C_COLD_FUNC __attribute__((noinline, cold))
#elif defined(_MSC_VER)
#define W2C_COLD_FUNC __declspec(noinline)
#else
#define W2C_COLD_FUNC
#endif

#define CHECK_CALL_INDIRECT(table, ft, x) \
(LIKELY((x) < table.size && table.data[x].func && \
func_types_eq(ft, table.data[x].func_type)) || \
TRAP(CALL_INDIRECT))
W2C_COLD_FUNC static bool func_types_eq_slowpath(
const wasm_rt_funcref_table_t* table,
const wasm_rt_func_type_t expected_type,
uint32_t index) {
const size_t sha256size = 32;
if (index >= table->size) {
// Table index out of bounds. Raise Wasm trap.
TRAP(CALL_INDIRECT);
return false;
}
const wasm_rt_funcref_t* const func_ref = &table->data[index];
if (!expected_type || !func_ref->func || !func_ref->func_type ||
memcmp(expected_type, func_ref->func_type, sha256size) != 0) {
// Type check failed. Raise Wasm trap.
TRAP(CALL_INDIRECT);
return false;
}
return true;
}

#define CHECK_CALL_INDIRECT(table, ft, x) \
(LIKELY((x) < table.size && ft == table.data[x].func_type) || \
func_types_eq_slowpath(&(table), ft, x))

#define DO_CALL_INDIRECT(table, t, x, ...) ((t)table.data[x].func)(__VA_ARGS__)

Expand Down
36 changes: 29 additions & 7 deletions test/wasm2c/export-names.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -165,15 +165,37 @@ static inline void wasm_rt_segue_write_base(void* base) {

#define UNREACHABLE TRAP(UNREACHABLE)

static inline bool func_types_eq(const wasm_rt_func_type_t a,
const wasm_rt_func_type_t b) {
return (a == b) || LIKELY(a && b && !memcmp(a, b, 32));
#if defined(__clang__) || defined(__GNUC__)
#define W2C_COLD_FUNC __attribute__((noinline, cold))
#elif defined(_MSC_VER)
#define W2C_COLD_FUNC __declspec(noinline)
#else
#define W2C_COLD_FUNC
#endif

W2C_COLD_FUNC static bool func_types_eq_slowpath(
const wasm_rt_funcref_table_t* table,
const wasm_rt_func_type_t expected_type,
uint32_t index) {
const size_t sha256size = 32;
if (index >= table->size) {
// Table index out of bounds. Raise Wasm trap.
TRAP(CALL_INDIRECT);
return false;
}
const wasm_rt_funcref_t* const func_ref = &table->data[index];
if (!expected_type || !func_ref->func || !func_ref->func_type ||
memcmp(expected_type, func_ref->func_type, sha256size) != 0) {
// Type check failed. Raise Wasm trap.
TRAP(CALL_INDIRECT);
return false;
}
return true;
}

#define CHECK_CALL_INDIRECT(table, ft, x) \
(LIKELY((x) < table.size && table.data[x].func && \
func_types_eq(ft, table.data[x].func_type)) || \
TRAP(CALL_INDIRECT))
#define CHECK_CALL_INDIRECT(table, ft, x) \
(LIKELY((x) < table.size && ft == table.data[x].func_type) || \
func_types_eq_slowpath(&(table), ft, x))

#define DO_CALL_INDIRECT(table, t, x, ...) ((t)table.data[x].func)(__VA_ARGS__)

Expand Down
38 changes: 30 additions & 8 deletions test/wasm2c/hello.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -172,15 +172,37 @@ static inline void wasm_rt_segue_write_base(void* base) {

#define UNREACHABLE TRAP(UNREACHABLE)

static inline bool func_types_eq(const wasm_rt_func_type_t a,
const wasm_rt_func_type_t b) {
return (a == b) || LIKELY(a && b && !memcmp(a, b, 32));
}
#if defined(__clang__) || defined(__GNUC__)
#define W2C_COLD_FUNC __attribute__((noinline, cold))
#elif defined(_MSC_VER)
#define W2C_COLD_FUNC __declspec(noinline)
#else
#define W2C_COLD_FUNC
#endif

#define CHECK_CALL_INDIRECT(table, ft, x) \
(LIKELY((x) < table.size && table.data[x].func && \
func_types_eq(ft, table.data[x].func_type)) || \
TRAP(CALL_INDIRECT))
W2C_COLD_FUNC static bool func_types_eq_slowpath(
const wasm_rt_funcref_table_t* table,
const wasm_rt_func_type_t expected_type,
uint32_t index) {
const size_t sha256size = 32;
if (index >= table->size) {
// Table index out of bounds. Raise Wasm trap.
TRAP(CALL_INDIRECT);
return false;
}
const wasm_rt_funcref_t* const func_ref = &table->data[index];
if (!expected_type || !func_ref->func || !func_ref->func_type ||
memcmp(expected_type, func_ref->func_type, sha256size) != 0) {
// Type check failed. Raise Wasm trap.
TRAP(CALL_INDIRECT);
return false;
}
return true;
}

#define CHECK_CALL_INDIRECT(table, ft, x) \
(LIKELY((x) < table.size && ft == table.data[x].func_type) || \
func_types_eq_slowpath(&(table), ft, x))

#define DO_CALL_INDIRECT(table, t, x, ...) ((t)table.data[x].func)(__VA_ARGS__)

Expand Down
38 changes: 30 additions & 8 deletions test/wasm2c/minimal.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -134,15 +134,37 @@ static inline void wasm_rt_segue_write_base(void* base) {

#define UNREACHABLE TRAP(UNREACHABLE)

static inline bool func_types_eq(const wasm_rt_func_type_t a,
const wasm_rt_func_type_t b) {
return (a == b) || LIKELY(a && b && !memcmp(a, b, 32));
}
#if defined(__clang__) || defined(__GNUC__)
#define W2C_COLD_FUNC __attribute__((noinline, cold))
#elif defined(_MSC_VER)
#define W2C_COLD_FUNC __declspec(noinline)
#else
#define W2C_COLD_FUNC
#endif

#define CHECK_CALL_INDIRECT(table, ft, x) \
(LIKELY((x) < table.size && table.data[x].func && \
func_types_eq(ft, table.data[x].func_type)) || \
TRAP(CALL_INDIRECT))
W2C_COLD_FUNC static bool func_types_eq_slowpath(
const wasm_rt_funcref_table_t* table,
const wasm_rt_func_type_t expected_type,
uint32_t index) {
const size_t sha256size = 32;
if (index >= table->size) {
// Table index out of bounds. Raise Wasm trap.
TRAP(CALL_INDIRECT);
return false;
}
const wasm_rt_funcref_t* const func_ref = &table->data[index];
if (!expected_type || !func_ref->func || !func_ref->func_type ||
memcmp(expected_type, func_ref->func_type, sha256size) != 0) {
// Type check failed. Raise Wasm trap.
TRAP(CALL_INDIRECT);
return false;
}
return true;
}

#define CHECK_CALL_INDIRECT(table, ft, x) \
(LIKELY((x) < table.size && ft == table.data[x].func_type) || \
func_types_eq_slowpath(&(table), ft, x))

#define DO_CALL_INDIRECT(table, t, x, ...) ((t)table.data[x].func)(__VA_ARGS__)

Expand Down
36 changes: 29 additions & 7 deletions test/wasm2c/tail-calls.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -164,15 +164,37 @@ static inline void wasm_rt_segue_write_base(void* base) {

#define UNREACHABLE TRAP(UNREACHABLE)

static inline bool func_types_eq(const wasm_rt_func_type_t a,
const wasm_rt_func_type_t b) {
return (a == b) || LIKELY(a && b && !memcmp(a, b, 32));
#if defined(__clang__) || defined(__GNUC__)
#define W2C_COLD_FUNC __attribute__((noinline, cold))
#elif defined(_MSC_VER)
#define W2C_COLD_FUNC __declspec(noinline)
#else
#define W2C_COLD_FUNC
#endif

W2C_COLD_FUNC static bool func_types_eq_slowpath(
const wasm_rt_funcref_table_t* table,
const wasm_rt_func_type_t expected_type,
uint32_t index) {
const size_t sha256size = 32;
if (index >= table->size) {
// Table index out of bounds. Raise Wasm trap.
TRAP(CALL_INDIRECT);
return false;
}
const wasm_rt_funcref_t* const func_ref = &table->data[index];
if (!expected_type || !func_ref->func || !func_ref->func_type ||
memcmp(expected_type, func_ref->func_type, sha256size) != 0) {
// Type check failed. Raise Wasm trap.
TRAP(CALL_INDIRECT);
return false;
}
return true;
}

#define CHECK_CALL_INDIRECT(table, ft, x) \
(LIKELY((x) < table.size && table.data[x].func && \
func_types_eq(ft, table.data[x].func_type)) || \
TRAP(CALL_INDIRECT))
#define CHECK_CALL_INDIRECT(table, ft, x) \
(LIKELY((x) < table.size && ft == table.data[x].func_type) || \
func_types_eq_slowpath(&(table), ft, x))

#define DO_CALL_INDIRECT(table, t, x, ...) ((t)table.data[x].func)(__VA_ARGS__)

Expand Down
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