wasm: add a webassembly compiler backend, based on using binaryen (#17368)

vlib/builtin/wasm/alloc.v

@@ -0,0 +1,81 @@
+[has_globals]
+module builtin
+
+// Shitty `sbrk` basic `malloc` and `free` impl
+// TODO: implement pure V `walloc` later
+
+const wasm_page_size = 64 * 1024
+
+__global g_heap_base = isize(0)
+
+fn init() {
+	g_heap_base = __memory_grow(3)
+	if g_heap_base == -1 {
+		panic('g_heap_base: malloc() == nil')
+	}
+	g_heap_base *= wasm_page_size
+}
+
+// malloc dynamically allocates a `n` bytes block of memory on the heap.
+// malloc returns a `byteptr` pointing to the memory address of the allocated space.
+// unlike the `calloc` family of functions - malloc will not zero the memory block.
+[unsafe]
+pub fn malloc(n isize) &u8 {
+	if n <= 0 {
+		panic('malloc(n <= 0)')
+	}
+
+	res := g_heap_base
+	g_heap_base += n
+
+	return &u8(res)
+}
+
+// free allows for manually freeing memory allocated at the address `ptr`.
+// currently does not free any memory.
+[unsafe]
+pub fn free(ptr voidptr) {
+	_ := ptr
+}
+
+// vcalloc dynamically allocates a zeroed `n` bytes block of memory on the heap.
+// vcalloc returns a `byteptr` pointing to the memory address of the allocated space.
+// Unlike `v_calloc` vcalloc checks for negative values given in `n`.
+[unsafe]
+pub fn vcalloc(n isize) &u8 {
+	if n <= 0 {
+		panic('vcalloc(n <= 0)')
+	} else if n == 0 {
+		return &u8(0)
+	}
+
+	res := unsafe { malloc(n) }
+
+	__memory_fill(res, 0, n)
+
+	return res
+}
+
+// vmemcpy copies n bytes from memory area src to memory area dest.
+// The memory areas **CAN** overlap. vmemcpy returns a pointer to `dest`.
+[unsafe]
+pub fn vmemcpy(dest voidptr, const_src voidptr, n isize) voidptr {
+	__memory_copy(dest, const_src, n)
+	return dest
+}
+
+// vmemmove copies n bytes from memory area src to memory area dest.
+// The memory areas **CAN** overlap. vmemmove returns a pointer to `dest`.
+[unsafe]
+pub fn vmemmove(dest voidptr, const_src voidptr, n isize) voidptr {
+	__memory_copy(dest, const_src, n)
+	return dest
+}
+
+// vmemset fills the first `n` bytes of the memory area pointed to by `s`,
+// with the constant byte `c`. It returns a pointer to the memory area `s`.
+[unsafe]
+pub fn vmemset(s voidptr, c int, n isize) voidptr {
+	__memory_fill(s, c, n)
+	return s
+}