wasm: bug fixes and memory based changes (#17497)

vlib/builtin/wasm/alloc.v

@@ -4,17 +4,7 @@ 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 = usize(__heap_base())
-
-__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.
@@ -26,7 +16,7 @@ pub fn malloc(n isize) &u8 {
 	}
 
 	res := g_heap_base
-	g_heap_base += n
+	g_heap_base += usize(n)
 
 	return &u8(res)
 }
@@ -37,45 +27,3 @@ pub fn malloc(n isize) &u8 {
 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
-}

vlib/builtin/wasm/builtin.v

@@ -1,5 +1,55 @@
 module builtin
 
-fn __memory_grow(size isize) isize
+fn __heap_base() voidptr
+fn __memory_size() usize
+fn __memory_grow(size usize) usize
 fn __memory_fill(dest &u8, value isize, size isize)
 fn __memory_copy(dest &u8, src &u8, size isize)
+
+// 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
+}
+
+// isnil returns true if an object is nil (only for C objects).
+[inline]
+pub fn isnil(v voidptr) bool {
+	return v == 0
+}
+
+// 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
+}

vlib/builtin/wasm/wasi/builtin.v

@@ -57,5 +57,6 @@ pub fn exit(code int) {
 pub fn panic(s string) {
 	eprint('V panic: ')
 	eprintln(s)
+	_ := *&u8(-1)
 	exit(1)
 }

vlib/v/gen/wasm/gen.v

@@ -36,7 +36,7 @@ mut:
 	stack_patches           []BlockPatch
 	needs_stack             bool // If true, will use `memory` and `__vsp`
 	constant_data           []ConstantData
-	constant_data_offset    int
+	constant_data_offset    int = 1024 // Low 1KiB of data unused, for optimisations
 	module_import_namespace string // `[wasm_import_namespace: 'wasi_snapshot_preview1']` else `env`
 	globals                 map[string]GlobalData
 }
@@ -159,7 +159,7 @@ fn (mut g Gen) function_return_wasm_type(typ ast.Type) binaryen.Type {
 	if typ == ast.void_type {
 		return type_none
 	}
-	types := g.unpack_type(typ).filter(g.table.sym(it).info !is ast.Struct).map(g.get_wasm_type(it))
+	types := g.unpack_type(typ).filter(it.is_real_pointer() || g.table.sym(it).info !is ast.Struct).map(g.get_wasm_type(it))
 	if types.len == 0 {
 		return type_none
 	}
@@ -216,8 +216,10 @@ fn (mut g Gen) bare_function(name string, expr binaryen.Expression) binaryen.Fun
 		temporaries << g.local_temporaries[idx].typ
 	}
 
+	wasm_expr := g.setup_stack_frame(expr)
+
 	func := binaryen.addfunction(g.mod, name.str, type_none, type_none, temporaries.data,
-		temporaries.len, expr)
+		temporaries.len, wasm_expr)
 
 	g.local_temporaries.clear()
 	g.local_addresses = map[string]Stack{}
@@ -272,7 +274,7 @@ fn (mut g Gen) fn_decl(node ast.FnDecl) {
 
 	for idx, typ in g.curr_ret {
 		sym := g.table.sym(typ)
-		if sym.info is ast.Struct {
+		if sym.info is ast.Struct && !typ.is_real_pointer() {
 			g.local_temporaries << Temporary{
 				name: '__return${idx}'
 				typ: type_i32 // pointer
@@ -318,7 +320,7 @@ fn (mut g Gen) fn_decl(node ast.FnDecl) {
 			node.pos.col)
 	}
 
-	if g.pref.printfn_list.len > 0 && node.name in g.pref.printfn_list {
+	if g.pref.printfn_list.len > 0 && name in g.pref.printfn_list {
 		binaryen.expressionprint(wasm_expr)
 	}
 
@@ -346,7 +348,7 @@ fn (mut g Gen) literalint(val i64, expected ast.Type) binaryen.Expression {
 		type_i64 { return binaryen.constant(g.mod, binaryen.literalint64(val)) }
 		else {}
 	}
-	g.w_error('literalint: bad type `${expected}`')
+	g.w_error('literalint: bad type `${*g.table.sym(expected)}`')
 }
 
 fn (mut g Gen) literal(val string, expected ast.Type) binaryen.Expression {
@@ -360,14 +362,23 @@ fn (mut g Gen) literal(val string, expected ast.Type) binaryen.Expression {
 	g.w_error('literal: bad type `${expected}`')
 }
 
+fn (mut g Gen) handle_ptr_arithmetic(typ ast.Type, expr binaryen.Expression) binaryen.Expression {
+	return if typ.is_ptr() {
+		size, _ := g.get_type_size_align(typ)
+		binaryen.binary(g.mod, binaryen.mulint32(), expr, g.literalint(size, ast.voidptr_type))
+	} else {
+		expr
+	}
+}
+
 fn (mut g Gen) postfix_expr(node ast.PostfixExpr) binaryen.Expression {
 	kind := if node.op == .inc { token.Kind.plus } else { token.Kind.minus }
 
 	var := g.get_var_from_expr(node.expr)
 	op := g.infix_from_typ(node.typ, kind)
 
-	expr := binaryen.binary(g.mod, op, g.get_or_lea_lop(var, node.typ), g.literal('1',
+	expr := binaryen.binary(g.mod, op, g.get_or_lea_lop(var, node.typ), g.handle_ptr_arithmetic(node.typ,
-		node.typ))
+		g.literal('0', node.typ)))
 
 	return g.set_var(var, expr, ast_typ: node.typ)
 }
@@ -395,8 +406,8 @@ fn (mut g Gen) infix_expr(node ast.InfixExpr, expected ast.Type) binaryen.Expres
 
 	op := g.infix_from_typ(node.left_type, node.op)
 
-	infix := binaryen.binary(g.mod, op, g.expr(node.left, node.left_type), g.expr_with_cast(node.right,
+	infix := binaryen.binary(g.mod, op, g.expr(node.left, node.left_type), g.handle_ptr_arithmetic(node.left_type,
-		node.right_type, node.left_type))
+		g.expr_with_cast(node.right, node.right_type, node.left_type)))
 
 	res_typ := if infix_kind_return_bool(node.op) {
 		ast.bool_type
@@ -492,7 +503,8 @@ fn (mut g Gen) if_expr(ifexpr ast.IfExpr) binaryen.Expression {
 	return g.if_branch(ifexpr, 0)
 }
 
-const wasm_builtins = ['__memory_grow', '__memory_fill', '__memory_copy']
+const wasm_builtins = ['__memory_grow', '__memory_fill', '__memory_copy', '__memory_size',
+	'__heap_base']
 
 fn (mut g Gen) wasm_builtin(name string, node ast.CallExpr) binaryen.Expression {
 	mut args := []binaryen.Expression{cap: node.args.len}
@@ -510,6 +522,12 @@ fn (mut g Gen) wasm_builtin(name string, node ast.CallExpr) binaryen.Expression
 		'__memory_copy' {
 			return binaryen.memorycopy(g.mod, args[0], args[1], args[2], c'memory', c'memory')
 		}
+		'__memory_size' {
+			return binaryen.memorysize(g.mod, c'memory', false)
+		}
+		'__heap_base' {
+			return binaryen.globalget(g.mod, c'__heap_base', type_i32)
+		}
 		else {
 			panic('unreachable')
 		}
@@ -666,6 +684,9 @@ fn (mut g Gen) expr_impl(node ast.Expr, expected ast.Type) binaryen.Expression {
 			g.literalint(off, ast.u32_type)
 		}
 		ast.SizeOf {
+			if !g.table.known_type_idx(node.typ) {
+				g.v_error('unknown type `${*g.table.sym(node.typ)}`', node.pos)
+			}
 			size, _ := g.table.type_size(node.typ)
 			g.literalint(size, ast.u32_type)
 		}
@@ -705,6 +726,9 @@ fn (mut g Gen) expr_impl(node ast.Expr, expected ast.Type) binaryen.Expression {
 		ast.IntegerLiteral, ast.FloatLiteral {
 			g.literal(node.val, expected)
 		}
+		ast.Nil {
+			g.literalint(0, expected)
+		}
 		ast.IfExpr {
 			if node.branches.len == 2 && node.is_expr {
 				left := g.expr_stmts(node.branches[0].stmts, expected)
@@ -755,7 +779,7 @@ fn (mut g Gen) expr_impl(node ast.Expr, expected ast.Type) binaryen.Expression {
 			}
 
 			ret_types := g.unpack_type(node.return_type)
-			structs := ret_types.filter(g.table.sym(it).info is ast.Struct)
+			structs := ret_types.filter(g.table.sym(it).info is ast.Struct && !it.is_real_pointer())
 			mut structs_addrs := []int{cap: structs.len}
 
 			// ABI: {return structs} {method `self`}, then {arguments}
@@ -926,7 +950,8 @@ fn (mut g Gen) expr_stmt(node ast.Stmt, expected ast.Type) binaryen.Expression {
 			mut leave_expr_list := []binaryen.Expression{cap: node.exprs.len}
 			mut exprs := []binaryen.Expression{cap: node.exprs.len}
 			for idx, expr in node.exprs {
-				if g.table.sym(g.curr_ret[idx]).info is ast.Struct {
+				typ := g.curr_ret[idx]
+				if g.table.sym(typ).info is ast.Struct && !typ.is_real_pointer() {
 					// Could be adapted to use random pointers?
 					/*
 					if expr is ast.StructInit {
@@ -934,12 +959,12 @@ fn (mut g Gen) expr_stmt(node ast.Stmt, expected ast.Type) binaryen.Expression {
 						leave_expr_list << g.init_struct(var, expr)
 					}*/
 					var := g.local_temporaries[g.get_local_temporary('__return${idx}')]
-					address := g.expr(expr, g.curr_ret[idx])
+					address := g.expr(expr, typ)
 
-					leave_expr_list << g.blit(address, g.curr_ret[idx], binaryen.localget(g.mod,
+					leave_expr_list << g.blit(address, typ, binaryen.localget(g.mod, var.idx,
-						var.idx, var.typ))
+						var.typ))
 				} else {
-					exprs << g.expr(expr, g.curr_ret[idx])
+					exprs << g.expr(expr, typ)
 				}
 			}
 
@@ -1179,9 +1204,11 @@ pub fn gen(files []&ast.File, table &ast.Table, out_name string, w_pref &pref.Pr
 		mod: binaryen.modulecreate()
 	}
 	g.table.pointer_size = 4
-	// Offset all pointers by 8, so that 0 never points to valid memory
-	g.constant_data_offset = 8
 	binaryen.modulesetfeatures(g.mod, binaryen.featureall())
+	binaryen.setlowmemoryunused(true) // Low 1KiB of memory is unused.
+	defer {
+		binaryen.moduledispose(g.mod)
+	}
 
 	if g.pref.os == .browser {
 		eprintln('`-os browser` is experimental and will not live up to expectations...')
@@ -1202,26 +1229,31 @@ pub fn gen(files []&ast.File, table &ast.Table, out_name string, w_pref &pref.Pr
 		g.needs_stack = true
 	}
 	g.housekeeping()
-	if binaryen.modulevalidate(g.mod) {
+
+	mut valid := binaryen.modulevalidate(g.mod)
+	if valid {
 		binaryen.setdebuginfo(w_pref.is_debug)
 		if w_pref.is_prod {
 			binaryen.setoptimizelevel(3)
 			binaryen.moduleoptimize(g.mod)
 		}
+	}
+
 	if out_name == '-' {
 		if g.pref.is_verbose {
 			binaryen.moduleprint(g.mod)
 		} else {
 			binaryen.moduleprintstackir(g.mod, w_pref.is_prod)
 		}
-		} else {
+	}
+
+	if !valid {
+		g.w_error('validation failed, this should not happen. report an issue with the above messages')
+	}
+
+	if out_name != '-' {
 		bytes := binaryen.moduleallocateandwrite(g.mod, unsafe { nil })
 		str := unsafe { (&char(bytes.binary)).vstring_with_len(int(bytes.binaryBytes)) }
 		os.write_file(out_name, str) or { panic(err) }
 	}
-	} else {
-		binaryen.moduledispose(g.mod)
-		g.w_error('validation failed, this should not happen. report an issue with the above messages')
-	}
-	binaryen.moduledispose(g.mod)
 }

vlib/v/gen/wasm/mem.v

@@ -142,7 +142,7 @@ fn (mut g Gen) get_or_lea_lop(lp LocalOrPointer, expected ast.Type) binaryen.Exp
 		}
 	}
 
-	if !is_expr && parent_typ == expected {
+	if (!is_expr && parent_typ == expected) || !g.is_pure_type(expected) {
 		return expr
 	}
 
@@ -235,6 +235,9 @@ fn (mut g Gen) get_var_from_expr(node ast.Expr) LocalOrPointer {
 		ast.Ident {
 			g.get_var_from_ident(node)
 		}
+		ast.ParExpr {
+			g.get_var_from_expr(node.expr)
+		}
 		ast.SelectorExpr {
 			address := g.get_var_from_expr(node.expr)
 			offset := g.get_field_offset(node.expr_type, node.field_name)

vlib/v/gen/wasm/ops.v

@@ -21,6 +21,7 @@ fn (mut g Gen) get_wasm_type(typ_ ast.Type) binaryen.Type {
 		return wasm.type_none
 	}
 	if typ.is_real_pointer() {
+		g.needs_stack = true
 		return wasm.type_i32
 	}
 	if typ in ast.number_type_idxs {
@@ -64,6 +65,9 @@ fn (mut g Gen) get_wasm_type(typ_ ast.Type) binaryen.Type {
 		ast.ArrayFixed {
 			return wasm.type_i32
 		}
+		ast.Enum {
+			return g.get_wasm_type(ts.info.typ)
+		}
 		else {}
 	}
 

vlib/v/gen/wasm/serialisation.v

@@ -130,6 +130,13 @@ fn (mut g Gen) housekeeping() {
 	// `_vinit` should be used to initialise the WASM module,
 	// then `main.main` can be called safely.
 	vinit := g.make_vinit()
+	stack_base := round_up_to_multiple(g.constant_data_offset, 1024)
+	heap_base := if g.needs_stack {
+		stack_base + 1024 * 16 // 16KiB of stack
+	} else {
+		stack_base
+	}
+	pages_needed := heap_base / (1024 * 64) + 1
 
 	if g.needs_stack || g.constant_data.len != 0 {
 		data := g.constant_data.map(it.data.data)
@@ -137,14 +144,14 @@ fn (mut g Gen) housekeeping() {
 		data_offsets := g.constant_data.map(binaryen.constant(g.mod, binaryen.literalint32(it.offset)))
 		passive := []bool{len: g.constant_data.len, init: false}
 
-		binaryen.setmemory(g.mod, 1, 4, c'memory', data.data, passive.data, data_offsets.data,
+		binaryen.setmemory(g.mod, pages_needed, pages_needed + 4, c'memory', data.data,
-			data_len.data, data.len, false, false, c'memory')
+			passive.data, data_offsets.data, data_len.data, data.len, false, false, c'memory')
+		binaryen.addglobal(g.mod, c'__heap_base', type_i32, false, g.literalint(heap_base,
+			ast.int_type))
 	}
 	if g.needs_stack {
 		// `g.constant_data_offset` rounded up to a multiple of 1024
-		offset := round_up_to_multiple(g.constant_data_offset, 1024)
+		binaryen.addglobal(g.mod, c'__vsp', type_i32, true, g.literalint(stack_base, ast.int_type))
-
-		binaryen.addglobal(g.mod, c'__vsp', type_i32, true, g.literalint(offset, ast.int_type))
 	}
 	if g.pref.os == .wasi {
 		main_expr := g.mkblock([binaryen.call(g.mod, c'_vinit', unsafe { nil }, 0, type_none),

vlib/v/gen/wasm/tests/arrays.vv

@@ -26,3 +26,14 @@ fn test_this(index int) int {
 	}
 	return 10
 }
+
+struct AA {
+	a [10]&int
+}
+
+fn main() {
+	a := AA{}
+
+	mut b := &int(0)
+	b = a.a[2]
+}