summaryrefslogtreecommitdiff
path: root/wasm2c
diff options
context:
space:
mode:
Diffstat (limited to 'wasm2c')
-rw-r--r--wasm2c/README.md13
-rw-r--r--wasm2c/examples/fac/fac.c130
-rw-r--r--wasm2c/wasm-rt-impl.c68
-rw-r--r--wasm2c/wasm-rt.h16
4 files changed, 143 insertions, 84 deletions
diff --git a/wasm2c/README.md b/wasm2c/README.md
index 6d68626e..6850b62c 100644
--- a/wasm2c/README.md
+++ b/wasm2c/README.md
@@ -92,6 +92,8 @@ int main(int argc, char** argv) {
}
```
+## Compiling the wasm2c output
+
To compile the executable, we need to use `main.c` and the generated `fac.c`.
We'll also include `wasm-rt-impl.c` which has implementations of the various
`wasm_rt_*` functions used by `fac.c` and `fac.h`.
@@ -100,6 +102,17 @@ We'll also include `wasm-rt-impl.c` which has implementations of the various
$ cc -o fac main.c fac.c wasm-rt-impl.c
```
+A note on compiling with optimization: wasm2c relies on certain
+behavior from the C compiler to maintain conformance with the
+WebAssembly specification, especially with regards to requirements to
+convert "signaling" to "quiet" floating-point NaN values and for
+infinite recursion to produce a trap. When compiling with optimization
+(e.g. `-O2` or `-O3`), it's necessary to disable some optimizations to
+preserve conformance. With GCC 11, adding the command-line arguments
+`-fno-optimize-sibling-calls -frounding-math -fsignaling-nans` appears
+to be sufficient. With clang 14, just `-fno-optimize-sibling-calls
+-frounding-math` appears to be sufficient.
+
Now let's test it out!
```sh
diff --git a/wasm2c/examples/fac/fac.c b/wasm2c/examples/fac/fac.c
index 30f1e9bb..106d7768 100644
--- a/wasm2c/examples/fac/fac.c
+++ b/wasm2c/examples/fac/fac.c
@@ -36,6 +36,12 @@
#define MEMCHECK(mem, a, t) RANGE_CHECK(mem, a, sizeof(t))
#endif
+#ifdef __GNUC__
+#define wasm_asm __asm__
+#else
+#define wasm_asm(X)
+#endif
+
#if WABT_BIG_ENDIAN
static inline void load_data(void* dest, const void* src, size_t n) {
size_t i = 0;
@@ -58,6 +64,7 @@ static inline void load_data(void* dest, const void* src, size_t n) {
t1 result; \
wasm_rt_memcpy(&result, &mem->data[mem->size - addr - sizeof(t1)], \
sizeof(t1)); \
+ wasm_asm("" ::"r"(result)); \
return (t3)(t2)result; \
}
@@ -82,6 +89,7 @@ static inline void load_data(void* dest, const void* src, size_t n) {
MEMCHECK(mem, addr, t1); \
t1 result; \
wasm_rt_memcpy(&result, &mem->data[addr], sizeof(t1)); \
+ wasm_asm("" ::"r"(result)); \
return (t3)(t2)result; \
}
@@ -319,6 +327,128 @@ DEFINE_REINTERPRET(i32_reinterpret_f32, f32, u32)
DEFINE_REINTERPRET(f64_reinterpret_i64, u64, f64)
DEFINE_REINTERPRET(i64_reinterpret_f64, f64, u64)
+static float quiet_nanf(float x) {
+ uint32_t tmp;
+ memcpy(&tmp, &x, 4);
+ tmp |= 0x7fc00000lu;
+ memcpy(&x, &tmp, 4);
+ return x;
+}
+
+static double quiet_nan(double x) {
+ uint64_t tmp;
+ memcpy(&tmp, &x, 8);
+ tmp |= 0x7ff8000000000000llu;
+ memcpy(&x, &tmp, 8);
+ return x;
+}
+
+static double wasm_quiet(double x) {
+ if (UNLIKELY(isnan(x))) {
+ return quiet_nan(x);
+ }
+ return x;
+}
+
+static float wasm_quietf(float x) {
+ if (UNLIKELY(isnan(x))) {
+ return quiet_nanf(x);
+ }
+ return x;
+}
+
+static double wasm_floor(double x) {
+ if (UNLIKELY(isnan(x))) {
+ return quiet_nan(x);
+ }
+ return floor(x);
+}
+
+static float wasm_floorf(float x) {
+ if (UNLIKELY(isnan(x))) {
+ return quiet_nanf(x);
+ }
+ return floorf(x);
+}
+
+static double wasm_ceil(double x) {
+ if (UNLIKELY(isnan(x))) {
+ return quiet_nan(x);
+ }
+ return ceil(x);
+}
+
+static float wasm_ceilf(float x) {
+ if (UNLIKELY(isnan(x))) {
+ return quiet_nanf(x);
+ }
+ return ceilf(x);
+}
+
+static double wasm_trunc(double x) {
+ if (UNLIKELY(isnan(x))) {
+ return quiet_nan(x);
+ }
+ return trunc(x);
+}
+
+static float wasm_truncf(float x) {
+ if (UNLIKELY(isnan(x))) {
+ return quiet_nanf(x);
+ }
+ return truncf(x);
+}
+
+static float wasm_nearbyintf(float x) {
+ if (UNLIKELY(isnan(x))) {
+ return quiet_nanf(x);
+ }
+ return nearbyintf(x);
+}
+
+static double wasm_nearbyint(double x) {
+ if (UNLIKELY(isnan(x))) {
+ return quiet_nan(x);
+ }
+ return nearbyint(x);
+}
+
+static float wasm_fabsf(float x) {
+ if (UNLIKELY(isnan(x))) {
+ uint32_t tmp;
+ memcpy(&tmp, &x, 4);
+ tmp = tmp & ~(1 << 31);
+ memcpy(&x, &tmp, 4);
+ return x;
+ }
+ return fabsf(x);
+}
+
+static double wasm_fabs(double x) {
+ if (UNLIKELY(isnan(x))) {
+ uint64_t tmp;
+ memcpy(&tmp, &x, 8);
+ tmp = tmp & ~(1ll << 63);
+ memcpy(&x, &tmp, 8);
+ return x;
+ }
+ return fabs(x);
+}
+
+static double wasm_sqrt(double x) {
+ if (UNLIKELY(isnan(x))) {
+ return quiet_nan(x);
+ }
+ return sqrt(x);
+}
+
+static float wasm_sqrtf(float x) {
+ if (UNLIKELY(isnan(x))) {
+ return quiet_nanf(x);
+ }
+ return sqrtf(x);
+}
+
static u32 func_types[1];
static void init_func_types(void) {
func_types[0] = wasm_rt_register_func_type(1, 1, WASM_RT_I32, WASM_RT_I32);
diff --git a/wasm2c/wasm-rt-impl.c b/wasm2c/wasm-rt-impl.c
index 7d70597c..14ca0e6f 100644
--- a/wasm2c/wasm-rt-impl.c
+++ b/wasm2c/wasm-rt-impl.c
@@ -290,74 +290,6 @@ void wasm_rt_free_memory(wasm_rt_memory_t* memory) {
#endif
}
-#ifdef _WIN32
-static float quiet_nanf(float x) {
- uint32_t tmp;
- memcpy(&tmp, &x, 4);
- tmp |= 0x7fc00000lu;
- memcpy(&x, &tmp, 4);
- return x;
-}
-
-static double quiet_nan(double x) {
- uint64_t tmp;
- memcpy(&tmp, &x, 8);
- tmp |= 0x7ff8000000000000llu;
- memcpy(&x, &tmp, 8);
- return x;
-}
-
-double wasm_rt_trunc(double x) {
- if (isnan(x)) {
- return quiet_nan(x);
- }
- return trunc(x);
-}
-
-float wasm_rt_truncf(float x) {
- if (isnan(x)) {
- return quiet_nanf(x);
- }
- return truncf(x);
-}
-
-float wasm_rt_nearbyintf(float x) {
- if (isnan(x)) {
- return quiet_nanf(x);
- }
- return nearbyintf(x);
-}
-
-double wasm_rt_nearbyint(double x) {
- if (isnan(x)) {
- return quiet_nan(x);
- }
- return nearbyint(x);
-}
-
-float wasm_rt_fabsf(float x) {
- if (isnan(x)) {
- uint32_t tmp;
- memcpy(&tmp, &x, 4);
- tmp = tmp & ~(1 << 31);
- memcpy(&x, &tmp, 4);
- return x;
- }
- return fabsf(x);
-}
-
-double wasm_rt_fabs(double x) {
- if (isnan(x)) {
- uint64_t tmp;
- memcpy(&tmp, &x, 8);
- tmp = tmp & ~(1ll << 63);
- memcpy(&x, &tmp, 8);
- return x;
- }
- return fabs(x);
-}
-#endif
-
void wasm_rt_allocate_table(wasm_rt_table_t* table,
uint32_t elements,
uint32_t max_elements) {
diff --git a/wasm2c/wasm-rt.h b/wasm2c/wasm-rt.h
index 167c4c40..fed82a27 100644
--- a/wasm2c/wasm-rt.h
+++ b/wasm2c/wasm-rt.h
@@ -264,22 +264,6 @@ void wasm_rt_allocate_table(wasm_rt_table_t*,
*/
void wasm_rt_free_table(wasm_rt_table_t*);
-#ifdef _WIN32
-float wasm_rt_truncf(float x);
-double wasm_rt_trunc(double x);
-float wasm_rt_nearbyintf(float x);
-double wasm_rt_nearbyint(double x);
-float wasm_rt_fabsf(float x);
-double wasm_rt_fabs(double x);
-#else
-#define wasm_rt_truncf(x) truncf(x)
-#define wasm_rt_trunc(x) trunc(x)
-#define wasm_rt_nearbyintf(x) nearbyintf(x)
-#define wasm_rt_nearbyint(x) nearbyint(x)
-#define wasm_rt_fabsf(x) fabsf(x)
-#define wasm_rt_fabs(x) fabs(x)
-#endif
-
#ifdef __cplusplus
}
#endif
generated by cgit v1.2.3 (git 2.39.1) at 2025-08-17 21:02:06 +0000