add load/store intrinsics

examples/microw8/mem_intrinsics.cwa

@@ -0,0 +1,16 @@
+import "env.memory" memory(4);
+import "env.random" fn random() -> i32;
+
+export fn upd() {
+    let i: i32;
+    loop pixels {
+        let inline left = i32.load8_u((i + (320*240 - 319)) % (320*240), 120);
+        let inline top = i32.load8_u((i + 320*239) % (320*240), 120, 0);
+        let inline here = i32.load16_u(i, 119);
+        let inline all = (left << 24) | (top << 16) | here;
+        let lazy r = random();
+        let inline new = (all #>> ((r & 3) * 8)) ^ ((r & 31) * !(r #>> 22));
+        i32.store8(new, i, 120);
+        branch_if (i := i + 1) < 320*240: pixels;
+    }
+}

src/ast.rs

@@ -288,7 +288,7 @@ impl Expr {
         Expression {
             type_: None,
             expr: self,
-            span: span,
+            span,
         }
     }
 }
@@ -337,6 +337,7 @@ pub enum BinOp {
 pub enum MemSize {
     Byte,
     Word,
+    Float
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Ord, PartialOrd)]

src/emit.rs

@@ -6,7 +6,11 @@ use wasm_encoder::{
     MemArg, MemoryType, Module, NameMap, NameSection, StartSection, TypeSection, ValType,
 };
 
-use crate::{ast, intrinsics::Intrinsics, Options};
+use crate::{
+    ast,
+    intrinsics::{Intrinsics, MemInstruction},
+    Options,
+};
 
 pub fn emit(script: &ast::Script, module_name: &str, options: &Options) -> Vec<u8> {
     let mut module = Module::new();
@@ -65,9 +69,7 @@ pub fn emit(script: &ast::Script, module_name: &str, options: &Options) -> Vec<u
                 } => {
                     function_map.insert(name.clone(), function_map.len() as u32);
                     EntityType::Function(
-                        *function_types
+                        *function_types.get(&(params.clone(), *result)).unwrap() as u32
-                            .get(&(params.clone(), result.clone()))
-                            .unwrap() as u32,
                     )
                 }
             };
@@ -254,9 +256,7 @@ fn collect_function_types(script: &ast::Script) -> HashMap<FunctionTypeKey, usiz
         } = import.type_
         {
             let index = types.len();
-            types
+            types.entry((params.clone(), *result)).or_insert(index);
-                .entry((params.clone(), result.clone()))
-                .or_insert(index);
         }
     }
 
@@ -346,6 +346,11 @@ fn mem_arg_for_location(mem_location: &ast::MemoryLocation) -> MemArg {
             memory_index: 0,
             offset,
         },
+        ast::MemSize::Float => MemArg {
+            align: 2,
+            memory_index: 0,
+            offset,
+        },
     }
 }
 
@@ -391,6 +396,7 @@ fn emit_expression<'a>(ctx: &mut FunctionContext<'a>, expr: &'a ast::Expression)
             ctx.function.instruction(&match mem_location.size {
                 ast::MemSize::Byte => Instruction::I32Load8_U(mem_arg),
                 ast::MemSize::Word => Instruction::I32Load(mem_arg),
+                ast::MemSize::Float => Instruction::F32Load(mem_arg),
             });
         }
         ast::Expr::Poke {
@@ -403,6 +409,7 @@ fn emit_expression<'a>(ctx: &mut FunctionContext<'a>, expr: &'a ast::Expression)
             ctx.function.instruction(&match mem_location.size {
                 ast::MemSize::Byte => Instruction::I32Store8(mem_arg),
                 ast::MemSize::Word => Instruction::I32Store(mem_arg),
+                ast::MemSize::Float => Instruction::F32Store(mem_arg),
             });
         }
         ast::Expr::UnaryOp { op, value } => {
@@ -654,6 +661,31 @@ fn emit_expression<'a>(ctx: &mut FunctionContext<'a>, expr: &'a ast::Expression)
             }
         }
         ast::Expr::FuncCall { name, params, .. } => {
+            fn mem_instruction(
+                inst: MemInstruction,
+                params: &[ast::Expression],
+            ) -> Instruction<'static> {
+                let offset = params
+                    .get(0)
+                    .map(|e| e.const_i32() as u32 as u64)
+                    .unwrap_or(0);
+                let alignment = params.get(1).map(|e| e.const_i32() as u32);
+                (inst.instruction)(MemArg {
+                    offset,
+                    align: alignment.unwrap_or(inst.natural_alignment),
+                    memory_index: 0,
+                })
+            }
+            if let Some(load) = ctx.intrinsics.find_load(name) {
+                emit_expression(ctx, &params[0]);
+                ctx.function
+                    .instruction(&mem_instruction(load, &params[1..]));
+            } else if let Some(store) = ctx.intrinsics.find_store(name) {
+                emit_expression(ctx, &params[1]);
+                emit_expression(ctx, &params[0]);
+                ctx.function
+                    .instruction(&mem_instruction(store, &params[2..]));
+            } else {
                 for param in params {
                     emit_expression(ctx, param);
                 }
@@ -669,6 +701,7 @@ fn emit_expression<'a>(ctx: &mut FunctionContext<'a>, expr: &'a ast::Expression)
                         .instruction(&ctx.intrinsics.get_instr(name, &types).unwrap());
                 }
             }
+        }
         ast::Expr::Select {
             condition,
             if_true,

src/includes.rs

@@ -9,11 +9,11 @@ pub fn resolve_includes(script: &mut ast::Script, path: &Path) -> Result<()> {
     let script_dir = path.parent().expect("Script path has no parent");
     for data in &mut script.data {
         for values in &mut data.data {
-            match values {
+            if let ast::DataValues::File {
-                ast::DataValues::File {
                 ref path,
                 ref mut data,
-                } => {
+            } = values
+            {
                 let mut full_path = script_dir.to_path_buf();
                 full_path.push(path);
                 File::open(&full_path)
@@ -22,8 +22,6 @@ pub fn resolve_includes(script: &mut ast::Script, path: &Path) -> Result<()> {
                     })?
                     .read_to_end(data)?;
             }
-                _ => (),
-            }
         }
     }
 

src/intrinsics.rs

@@ -1,5 +1,6 @@
 use crate::ast::Type;
 use std::collections::HashMap;
+use enc::MemArg;
 use wasm_encoder as enc;
 
 pub struct Intrinsics(HashMap<String, HashMap<Vec<Type>, (Type, enc::Instruction<'static>)>>);
@@ -137,4 +138,59 @@ impl Intrinsics {
             .or_default()
             .insert(params.to_vec(), (ret, ins.clone()));
     }
+
+    pub fn find_load(&self, name: &str) -> Option<MemInstruction> {
+        use enc::Instruction as I;
+        use Type::*;
+        let ins = match name {
+            "i32.load" => MemInstruction::new(I32, I::I32Load, 2),
+            "i32.load8_s" => MemInstruction::new(I32, I::I32Load8_S, 0),
+            "i32.load8_u" => MemInstruction::new(I32, I::I32Load8_U, 0),
+            "i32.load16_s" => MemInstruction::new(I32, I::I32Load16_S, 1),
+            "i32.load16_u" => MemInstruction::new(I32, I::I32Load16_U, 1),
+            "i64.load" => MemInstruction::new(I64, I::I64Load, 3),
+            "i64.load8_s" => MemInstruction::new(I64, I::I64Load8_S, 0),
+            "i64.load8_u" => MemInstruction::new(I64, I::I64Load8_U, 0),
+            "i64.load16_s" => MemInstruction::new(I64, I::I64Load16_S, 1),
+            "i64.load16_u" => MemInstruction::new(I64, I::I64Load16_U, 1),
+            "i64.load32_s" => MemInstruction::new(I64, I::I64Load32_S, 2),
+            "i64.load32_u" => MemInstruction::new(I64, I::I64Load32_U, 2),
+            "f32.load" => MemInstruction::new(F32, I::F32Load, 2),
+            "f64.load" => MemInstruction::new(F64, I::F64Load, 3),
+            _ => return None
+        };
+        return Some(ins);
+    }
+
+    pub fn find_store(&self, name: &str) -> Option<MemInstruction> {
+        use enc::Instruction as I;
+        use Type::*;
+        let ins = match name {
+            "i32.store" => MemInstruction::new(I32, I::I32Store, 2),
+            "i32.store8" => MemInstruction::new(I32, I::I32Store8, 0),
+            "i32.store16" => MemInstruction::new(I32, I::I32Store16, 1),
+            "i64.store" => MemInstruction::new(I64, I::I64Store, 3),
+            "i64.store8" => MemInstruction::new(I64, I::I64Store8, 0),
+            "i64.store16" => MemInstruction::new(I64, I::I64Store16, 1),
+            "i64.store32" => MemInstruction::new(I64, I::I64Store32, 2),
+            "f32.store" => MemInstruction::new(F32, I::F32Store, 2),
+            "f64.store" => MemInstruction::new(F64, I::F64Store, 3),
+            _ => return None
+        };
+        return Some(ins);
+    }
+}
+
+pub struct MemInstruction {
+    pub type_: Type,
+    pub instruction: fn(MemArg) -> enc::Instruction<'static>,
+    pub natural_alignment: u32
+}
+
+impl MemInstruction {
+    fn new(type_: Type, instruction: fn(MemArg) -> enc::Instruction<'static>, natural_alignment: u32) -> MemInstruction {
+        MemInstruction {
+            type_, instruction, natural_alignment
+        }
+    }
 }

src/lib.rs

@@ -20,10 +20,7 @@ pub struct Options {
 
 impl Options {
     pub fn with_debug(self) -> Self {
-        Options {
+        Options { debug: true }
-            debug: true,
-            ..self
-        }
     }
 }
 
@@ -36,7 +33,7 @@ pub fn compile_file<P: AsRef<Path>>(path: P, options: Options) -> Result<Vec<u8>
 }
 
 pub fn compile_str(input: &str, path: &Path, options: Options) -> Result<Vec<u8>> {
-    let mut script = match parser::parse(&input) {
+    let mut script = match parser::parse(input) {
         Ok(script) => script,
         Err(_) => bail!("Parse failed"),
     };
@@ -44,7 +41,7 @@ pub fn compile_str(input: &str, path: &Path, options: Options) -> Result<Vec<u8>
     includes::resolve_includes(&mut script, path)?;
 
     constfold::fold_script(&mut script);
-    if let Err(_) = typecheck::tc_script(&mut script, &input) {
+    if typecheck::tc_script(&mut script, input).is_err() {
         bail!("Type check failed");
     }
     let wasm = emit::emit(

src/parser.rs

@@ -183,7 +183,8 @@ fn lexer() -> impl Parser<char, Vec<(Token, Span)>, Error = Simple<char>> {
             u64::from_str_radix(&n, 16).map_err(|err| Simple::custom(span, err.to_string()))
         })
         .or(text::int(10).try_map(|n: String, span: Span| {
-            u64::from_str_radix(&n, 10).map_err(|err| Simple::custom(span, err.to_string()))
+            n.parse::<u64>()
+                .map_err(|err| Simple::custom(span, err.to_string()))
         }))
         .boxed();
 
@@ -211,7 +212,7 @@ fn lexer() -> impl Parser<char, Vec<(Token, Span)>, Error = Simple<char>> {
         .collect::<String>()
         .map(Token::Op);
 
-    let ctrl = one_of("(){};,:?!".chars()).map(Token::Ctrl);
+    let ctrl = one_of("(){};,:?!$".chars()).map(Token::Ctrl);
 
     fn ident() -> impl Parser<char, String, Error = Simple<char>> + Copy + Clone {
         filter(|c: &char| c.is_ascii_alphabetic() || *c == '_')
@@ -358,7 +359,7 @@ fn script_parser() -> impl Parser<Token, ast::Script, Error = Simple<Token>> + C
 
             let branch = just(Token::Branch)
                 .ignore_then(identifier)
-                .map(|label| ast::Expr::Branch(label));
+                .map(ast::Expr::Branch);
 
             let branch_if = just(Token::BranchIf)
                 .ignore_then(expression.clone())
@@ -377,7 +378,7 @@ fn script_parser() -> impl Parser<Token, ast::Script, Error = Simple<Token>> + C
                         .or(just(Token::Inline).to(ast::LetType::Inline)))
                     .or_not(),
                 )
-                .then(identifier.clone())
+                .then(identifier)
                 .then(just(Token::Ctrl(':')).ignore_then(type_parser()).or_not())
                 .then(
                     just(Token::Op("=".to_string()))
@@ -394,7 +395,6 @@ fn script_parser() -> impl Parser<Token, ast::Script, Error = Simple<Token>> + C
                 .boxed();
 
             let assign = identifier
-                .clone()
                 .then_ignore(just(Token::Op("=".to_string())))
                 .then(expression.clone())
                 .map(|(name, value)| ast::Expr::Assign {
@@ -422,7 +422,6 @@ fn script_parser() -> impl Parser<Token, ast::Script, Error = Simple<Token>> + C
                 .boxed();
 
             let function_call = identifier
-                .clone()
                 .then(
                     expression
                         .clone()
@@ -499,7 +498,8 @@ fn script_parser() -> impl Parser<Token, ast::Script, Error = Simple<Token>> + C
 
             let mem_size = just(Token::Ctrl('?'))
                 .to(ast::MemSize::Byte)
-                .or(just(Token::Ctrl('!')).to(ast::MemSize::Word));
+                .or(just(Token::Ctrl('!')).to(ast::MemSize::Word))
+                .or(just(Token::Ctrl('$')).to(ast::MemSize::Float));
 
             let mem_op = mem_size.then(op_cast.clone());
 
@@ -676,7 +676,7 @@ fn script_parser() -> impl Parser<Token, ast::Script, Error = Simple<Token>> + C
                 })
                 .boxed();
 
-            let op_first = op_bit
+            op_bit
                 .clone()
                 .then(
                     just(Token::Op("<|".to_string()))
@@ -691,9 +691,7 @@ fn script_parser() -> impl Parser<Token, ast::Script, Error = Simple<Token>> + C
                     }
                     .with_span(span)
                 })
-                .boxed();
+                .boxed()
-
-            op_first
         });
 
         expression_out = Some(expression.clone());
@@ -718,7 +716,7 @@ fn script_parser() -> impl Parser<Token, ast::Script, Error = Simple<Token>> + C
                 }
                 ast::Expr::Block {
                     statements: statements.into_iter().map(|(expr, _)| expr).collect(),
-                    final_expression: final_expression.map(|e| Box::new(e)),
+                    final_expression: final_expression.map(Box::new),
                 }
                 .with_span(span)
             })
@@ -740,7 +738,7 @@ fn script_parser() -> impl Parser<Token, ast::Script, Error = Simple<Token>> + C
 
         let import_global = just(Token::Global)
             .ignore_then(just(Token::Mut).or_not())
-            .then(identifier.clone())
+            .then(identifier)
             .then_ignore(just(Token::Ctrl(':')))
             .then(type_parser())
             .map(|((mut_opt, name), type_)| ast::ImportType::Variable {
@@ -751,7 +749,7 @@ fn script_parser() -> impl Parser<Token, ast::Script, Error = Simple<Token>> + C
             .boxed();
 
         let import_function = just(Token::Fn)
-            .ignore_then(identifier.clone())
+            .ignore_then(identifier)
             .then(
                 type_parser()
                     .separated_by(just(Token::Ctrl(',')))
@@ -783,7 +781,6 @@ fn script_parser() -> impl Parser<Token, ast::Script, Error = Simple<Token>> + C
             .boxed();
 
         let parameter = identifier
-            .clone()
             .then_ignore(just(Token::Ctrl(':')))
             .then(type_parser())
             .boxed();
@@ -792,7 +789,7 @@ fn script_parser() -> impl Parser<Token, ast::Script, Error = Simple<Token>> + C
             .or_not()
             .then(just(Token::Ident("start".to_string())).or_not())
             .then_ignore(just(Token::Fn))
-            .then(identifier.clone())
+            .then(identifier)
             .then(
                 parameter
                     .separated_by(just(Token::Ctrl(',')))
@@ -820,7 +817,7 @@ fn script_parser() -> impl Parser<Token, ast::Script, Error = Simple<Token>> + C
 
         let global = just(Token::Global)
             .ignore_then(just(Token::Mut).or_not())
-            .then(identifier.clone())
+            .then(identifier)
             .then(just(Token::Ctrl(':')).ignore_then(type_parser()).or_not())
             .then(just(Token::Op("=".to_string())).ignore_then(expression.clone()))
             .then_ignore(just(Token::Ctrl(';')))
@@ -850,7 +847,7 @@ fn script_parser() -> impl Parser<Token, ast::Script, Error = Simple<Token>> + C
             )
             .map(|(type_, values)| ast::DataValues::Array { type_, values });
 
-        let data_string = string.clone().map(|s| ast::DataValues::String(s));
+        let data_string = string.clone().map(ast::DataValues::String);
 
         let data_file = just(Token::Ident("file".to_string()))
             .ignore_then(

src/typecheck.rs

@@ -1,7 +1,7 @@
 use ariadne::{Color, Label, Report, ReportKind, Source};
 use std::collections::HashMap;
 
-use crate::ast;
+use crate::ast::{self, MemSize};
 use crate::intrinsics::Intrinsics;
 use crate::Span;
 use ast::Type::*;
@@ -160,7 +160,7 @@ pub fn tc_script(script: &mut ast::Script, source: &str) -> Result<()> {
             context.locals.locals[index].index = Some((locals_start + id) as u32);
         }
 
-        f.locals = std::mem::replace(&mut context.locals, ast::Locals::default());
+        f.locals = std::mem::take(&mut context.locals);
 
         if f.body.type_ != f.type_ {
             result = type_mismatch(f.type_, &f.span, f.body.type_, &f.body.span, source);
@@ -333,7 +333,7 @@ fn type_mismatch(
                     "Expected type {:?}...",
                     type1
                         .map(|t| format!("{:?}", t))
-                        .unwrap_or("void".to_string())
+                        .unwrap_or_else(|| "void".to_string())
                 ))
                 .with_color(Color::Yellow),
         )
@@ -343,7 +343,7 @@ fn type_mismatch(
                     "...but found type {}",
                     type2
                         .map(|t| format!("{:?}", t))
-                        .unwrap_or("void".to_string())
+                        .unwrap_or_else(|| "void".to_string())
                 ))
                 .with_color(Color::Red),
         )
@@ -353,12 +353,12 @@ fn type_mismatch(
     Err(())
 }
 
-fn expected_type(span: &Span, source: &str) -> Result<()> {
+fn report_error(msg: &str, span: &Span, source: &str) -> Result<()> {
     Report::build(ReportKind::Error, (), span.start)
-        .with_message("Expected value but found expression of type void")
+        .with_message(msg)
         .with_label(
             Label::new(span.clone())
-                .with_message("Expected value but found expression of type void")
+                .with_message(msg)
                 .with_color(Color::Red),
         )
         .finish()
@@ -367,46 +367,24 @@ fn expected_type(span: &Span, source: &str) -> Result<()> {
     Err(())
 }
 
+fn expected_type(span: &Span, source: &str) -> Result<()> {
+    report_error(
+        "Expected value but found expression of type void",
+        span,
+        source,
+    )
+}
+
 fn unknown_variable(span: &Span, source: &str) -> Result<()> {
-    Report::build(ReportKind::Error, (), span.start)
+    report_error("Unknown variable", span, source)
-        .with_message("Unknown variable")
-        .with_label(
-            Label::new(span.clone())
-                .with_message("Unknown variable")
-                .with_color(Color::Red),
-        )
-        .finish()
-        .eprint(Source::from(source))
-        .unwrap();
-    Err(())
 }
 
 fn immutable_assign(span: &Span, source: &str) -> Result<()> {
-    Report::build(ReportKind::Error, (), span.start)
+    report_error("Trying to assign to immutable variable", span, source)
-        .with_message("Trying to assign to immutable variable")
-        .with_label(
-            Label::new(span.clone())
-                .with_message("Trying to assign to immutable variable")
-                .with_color(Color::Red),
-        )
-        .finish()
-        .eprint(Source::from(source))
-        .unwrap();
-    Err(())
 }
 
 fn missing_label(span: &Span, source: &str) -> Result<()> {
-    Report::build(ReportKind::Error, (), span.start)
+    report_error("Label not found", span, source)
-        .with_message("Label not found")
-        .with_label(
-            Label::new(span.clone())
-                .with_message("Label not found")
-                .with_color(Color::Red),
-        )
-        .finish()
-        .eprint(Source::from(source))
-        .unwrap();
-    return Err(());
 }
 
 fn tc_expression(context: &mut Context, expr: &mut ast::Expression) -> Result<()> {
@@ -471,23 +449,17 @@ fn tc_expression(context: &mut Context, expr: &mut ast::Expression) -> Result<()
                 *local_id = Some(id);
                 context.local_vars.insert(name.clone(), id);
             } else {
-                Report::build(ReportKind::Error, (), expr.span.start)
+                return report_error("Type missing", &expr.span, context.source);
-                    .with_message("Type missing")
-                    .with_label(
-                        Label::new(expr.span.clone())
-                            .with_message("Type missing")
-                            .with_color(Color::Red),
-                    )
-                    .finish()
-                    .eprint(Source::from(context.source))
-                    .unwrap();
-                return Err(());
             }
             None
         }
         ast::Expr::Peek(ref mut mem_location) => {
             tc_mem_location(context, mem_location)?;
-            Some(I32)
+            let ty = match mem_location.size {
+                MemSize::Float => F32,
+                _ => I32,
+            };
+            Some(ty)
         }
         ast::Expr::Poke {
             ref mut mem_location,
@@ -495,9 +467,13 @@ fn tc_expression(context: &mut Context, expr: &mut ast::Expression) -> Result<()
         } => {
             tc_mem_location(context, mem_location)?;
             tc_expression(context, value)?;
-            if value.type_ != Some(I32) {
+            let ty = match mem_location.size {
+                MemSize::Float => F32,
+                _ => I32,
+            };
+            if value.type_ != Some(ty) {
                 return type_mismatch(
-                    Some(I32),
+                    Some(ty),
                     &expr.span,
                     value.type_,
                     &value.span,
@@ -725,7 +701,27 @@ fn tc_expression(context: &mut Context, expr: &mut ast::Expression) -> Result<()
                     return expected_type(&param.span, context.source);
                 }
             }
-            if let Some(type_map) = context
+            if let Some(load) = context.intrinsics.find_load(name) {
+                tc_memarg(context, params.as_mut_slice(), &expr.span)?;
+                Some(load.type_)
+            } else if let Some(store) = context.intrinsics.find_store(name) {
+                if let Some(value) = params.first_mut() {
+                    tc_expression(context, value)?;
+                    if value.type_ != Some(store.type_) {
+                        type_mismatch(
+                            Some(store.type_),
+                            &expr.span,
+                            value.type_,
+                            &value.span,
+                            context.source,
+                        )?;
+                    }
+                } else {
+                    return report_error("Missing parameters", &expr.span, context.source);
+                }
+                tc_memarg(context, &mut params[1..], &expr.span)?;
+                None
+            } else if let Some(type_map) = context
                 .functions
                 .get(name)
                 .map(|fnc| HashMap::from_iter([(fnc.params.clone(), fnc.type_)]))
@@ -759,17 +755,11 @@ fn tc_expression(context: &mut Context, expr: &mut ast::Expression) -> Result<()
                     return Err(());
                 }
             } else {
-                Report::build(ReportKind::Error, (), expr.span.start)
+                return report_error(
-                    .with_message(format!("Unknown function {}", name))
+                    &format!("Unknown function {}", name),
-                    .with_label(
+                    &expr.span,
-                        Label::new(expr.span.clone())
+                    context.source,
-                            .with_message(format!("Unknown function {}", name))
+                );
-                            .with_color(Color::Red),
-                    )
-                    .finish()
-                    .eprint(Source::from(context.source))
-                    .unwrap();
-                return Err(());
             }
         }
         ast::Expr::Select {
@@ -890,19 +880,40 @@ fn tc_const(expr: &mut ast::Expression, source: &str) -> Result<()> {
         I64Const(_) => I64,
         F32Const(_) => F32,
         F64Const(_) => F64,
-        _ => {
+        _ => return report_error("Expected constant value", &expr.span, source),
-            Report::build(ReportKind::Error, (), expr.span.start)
-                .with_message("Expected constant value")
-                .with_label(
-                    Label::new(expr.span.clone())
-                        .with_message("Expected constant value")
-                        .with_color(Color::Red),
-                )
-                .finish()
-                .eprint(Source::from(source))
-                .unwrap();
-            return Err(());
-        }
     });
     Ok(())
 }
+
+fn tc_memarg(context: &mut Context, params: &mut [ast::Expression], span: &Span) -> Result<()> {
+    if params.is_empty() || params.len() > 3 {
+        let msg = if params.is_empty() {
+            "Missing base address parameter"
+        } else {
+            "Too many MemArg parameters"
+        };
+        return report_error(msg, span, context.source);
+    }
+
+    for (index, param) in params.iter_mut().enumerate() {
+        tc_expression(context, param)?;
+        if param.type_ != Some(I32) {
+            return type_mismatch(Some(I32), &span, param.type_, &param.span, context.source);
+        }
+        if index > 0 {
+            tc_const(param, context.source)?;
+        }
+        if index == 2 {
+            let align = param.const_i32();
+            if align < 0 || align > 4 {
+                return report_error(
+                    &format!("Alignment {} out of range (0-4)", align),
+                    &param.span,
+                    context.source,
+                );
+            }
+        }
+    }
+
+    Ok(())
+}