WIP: almost-complete Wasm backend.

src/backend/mod.rs

@@ -2,11 +2,14 @@
 
 use crate::cfg::CFGInfo;
 use crate::entity::EntityRef;
-use crate::ir::{FunctionBody, Value, ValueDef};
+use crate::ir::{
+    ExportKind, Func, FuncDecl, FunctionBody, ImportKind, Module, Type, Value, ValueDef,
+};
 use crate::passes::rpo::RPO;
 use crate::Operator;
 use anyhow::Result;
 use std::borrow::Cow;
+use std::collections::HashMap;
 
 pub mod stackify;
 use stackify::{Context as StackifyContext, WasmBlock};
@@ -15,7 +18,7 @@ use treeify::Trees;
 pub mod localify;
 use localify::Localifier;
 
-pub struct WasmBackend<'a> {
+pub struct WasmFuncBackend<'a> {
     body: &'a FunctionBody,
     rpo: RPO,
     trees: Trees,
@@ -29,8 +32,8 @@ macro_rules! op {
     };
 }
 
-impl<'a> WasmBackend<'a> {
-    pub fn new(body: &'a FunctionBody) -> Result<WasmBackend<'a>> {
+impl<'a> WasmFuncBackend<'a> {
+    pub fn new(body: &'a FunctionBody) -> Result<WasmFuncBackend<'a>> {
         log::debug!("Backend compiling:\n{}\n", body.display_verbose("| "));
         let cfg = CFGInfo::new(body);
         let rpo = RPO::compute(body);
@@ -41,7 +44,7 @@ impl<'a> WasmBackend<'a> {
         log::debug!("Ctrl:\n{:?}\n", ctrl);
         let locals = Localifier::compute(body, &cfg, &trees);
         log::debug!("Locals:\n{:?}\n", locals);
-        Ok(WasmBackend {
+        Ok(WasmFuncBackend {
             body,
             rpo,
             trees,
@@ -55,6 +58,7 @@ impl<'a> WasmBackend<'a> {
             self.locals
                 .locals
                 .values()
+                .skip(self.body.blocks[self.body.entry].params.len())
                 .map(|&ty| (1, wasm_encoder::ValType::from(ty)))
                 .collect::<Vec<_>>(),
         );
@@ -73,6 +77,7 @@ impl<'a> WasmBackend<'a> {
             }
             _ => {}
         }
+        func.instruction(&wasm_encoder::Instruction::End);
 
         log::debug!("Compiled to:\n{:?}\n", func);
 
@@ -503,3 +508,188 @@ impl<'a> WasmBackend<'a> {
         }
     }
 }
+
+pub fn compile(module: &Module<'_>) -> anyhow::Result<Vec<u8>> {
+    let mut into_mod = wasm_encoder::Module::new();
+
+    let mut types = wasm_encoder::TypeSection::new();
+    for (_sig, sig_data) in module.signatures() {
+        let params = sig_data
+            .params
+            .iter()
+            .map(|&ty| wasm_encoder::ValType::from(ty));
+        let returns = sig_data
+            .returns
+            .iter()
+            .map(|&ty| wasm_encoder::ValType::from(ty));
+        types.function(params, returns);
+    }
+    into_mod.section(&types);
+
+    let mut imports = wasm_encoder::ImportSection::new();
+    let import_map = module
+        .imports()
+        .filter_map(|import| match &import.kind {
+            &ImportKind::Func(func) => Some((func, (&import.module[..], &import.name[..]))),
+            _ => None,
+        })
+        .collect::<HashMap<Func, (&str, &str)>>();
+    let mut num_imports = 0;
+    for (i, (func, func_decl)) in module.funcs().enumerate() {
+        match func_decl {
+            FuncDecl::Import(sig) => {
+                let (module_name, func_name) = import_map.get(&func).unwrap_or(&("", ""));
+                imports.import(
+                    module_name,
+                    func_name,
+                    wasm_encoder::EntityType::Function(sig.index() as u32),
+                );
+            }
+            FuncDecl::Body(..) => {
+                num_imports = i;
+                break;
+            }
+        }
+    }
+    into_mod.section(&imports);
+
+    let mut funcs = wasm_encoder::FunctionSection::new();
+    for (func, func_decl) in module.funcs().skip(num_imports) {
+        match func_decl {
+            FuncDecl::Import(_) => anyhow::bail!("Import comes after func with body: {}", func),
+            FuncDecl::Body(sig, _) => {
+                funcs.function(sig.index() as u32);
+            }
+        }
+    }
+    into_mod.section(&funcs);
+
+    let mut tables = wasm_encoder::TableSection::new();
+    for (_table, table_data) in module.tables() {
+        tables.table(wasm_encoder::TableType {
+            element_type: wasm_encoder::ValType::from(table_data.ty),
+            minimum: table_data
+                .func_elements
+                .as_ref()
+                .map(|elt| elt.len())
+                .unwrap_or(0) as u32,
+            maximum: table_data.max,
+        });
+    }
+    into_mod.section(&tables);
+
+    let mut memories = wasm_encoder::MemorySection::new();
+    for (_mem, mem_data) in module.memories() {
+        memories.memory(wasm_encoder::MemoryType {
+            minimum: mem_data.initial_pages as u64,
+            maximum: mem_data.maximum_pages.map(|val| val as u64),
+            memory64: false,
+            shared: false,
+        });
+    }
+    into_mod.section(&memories);
+
+    let mut globals = wasm_encoder::GlobalSection::new();
+    for (_global, global_data) in module.globals() {
+        globals.global(
+            wasm_encoder::GlobalType {
+                val_type: wasm_encoder::ValType::from(global_data.ty),
+                mutable: global_data.mutable,
+            },
+            &const_init(global_data.ty, global_data.value),
+        );
+    }
+    into_mod.section(&globals);
+
+    let mut exports = wasm_encoder::ExportSection::new();
+    for export in module.exports() {
+        match &export.kind {
+            &ExportKind::Table(table) => {
+                exports.export(
+                    &export.name[..],
+                    wasm_encoder::ExportKind::Table,
+                    table.index() as u32,
+                );
+            }
+            &ExportKind::Func(func) => {
+                exports.export(
+                    &export.name[..],
+                    wasm_encoder::ExportKind::Func,
+                    func.index() as u32,
+                );
+            }
+            &ExportKind::Memory(mem) => {
+                exports.export(
+                    &export.name[..],
+                    wasm_encoder::ExportKind::Memory,
+                    mem.index() as u32,
+                );
+            }
+            &ExportKind::Global(global) => {
+                exports.export(
+                    &export.name[..],
+                    wasm_encoder::ExportKind::Global,
+                    global.index() as u32,
+                );
+            }
+        }
+    }
+    into_mod.section(&exports);
+
+    if let Some(start) = module.start_func {
+        let start = wasm_encoder::StartSection {
+            function_index: start.index() as u32,
+        };
+        into_mod.section(&start);
+    }
+
+    let mut elem = wasm_encoder::ElementSection::new();
+    for (table, table_data) in module.tables() {
+        if let Some(elts) = &table_data.func_elements {
+            for (i, &elt) in elts.iter().enumerate() {
+                if elt.is_valid() {
+                    elem.active(
+                        Some(table.index() as u32),
+                        &wasm_encoder::ConstExpr::i32_const(i as i32),
+                        wasm_encoder::ValType::FuncRef,
+                        wasm_encoder::Elements::Functions(&[elt.index() as u32]),
+                    );
+                }
+            }
+        }
+    }
+    into_mod.section(&elem);
+
+    let mut code = wasm_encoder::CodeSection::new();
+    for (_func, func_decl) in module.funcs().skip(num_imports) {
+        let body = func_decl.body().unwrap();
+        let body = WasmFuncBackend::new(body)?.compile()?;
+        code.function(&body);
+    }
+    into_mod.section(&code);
+
+    let mut data = wasm_encoder::DataSection::new();
+    for (mem, mem_data) in module.memories() {
+        for segment in &mem_data.segments {
+            data.active(
+                mem.index() as u32,
+                &wasm_encoder::ConstExpr::i32_const(segment.offset as i32),
+                segment.data.iter().copied(),
+            );
+        }
+    }
+    into_mod.section(&data);
+
+    Ok(into_mod.finish())
+}
+
+fn const_init(ty: Type, value: Option<u64>) -> wasm_encoder::ConstExpr {
+    let bits = value.unwrap_or(0);
+    match ty {
+        Type::I32 => wasm_encoder::ConstExpr::i32_const(bits as u32 as i32),
+        Type::I64 => wasm_encoder::ConstExpr::i64_const(bits as i64),
+        Type::F32 => wasm_encoder::ConstExpr::f32_const(f32::from_bits(bits as u32)),
+        Type::F64 => wasm_encoder::ConstExpr::f64_const(f64::from_bits(bits as u64)),
+        _ => unimplemented!(),
+    }
+}

src/frontend.rs

@@ -221,6 +221,9 @@ fn handle_payload<'a>(
             }
         }
         Payload::End(_) => {}
+        Payload::StartSection { func, .. } => {
+            module.start_func = Some(Func::from(func));
+        }
         payload => {
             log::warn!("Skipping section: {:?}", payload);
         }

src/ir/display.rs

@@ -147,6 +147,9 @@ pub struct ModuleDisplay<'a>(pub(crate) &'a Module<'a>);
 impl<'a> Display for ModuleDisplay<'a> {
     fn fmt(&self, f: &mut Formatter) -> FmtResult {
         writeln!(f, "module {{")?;
+        if let Some(func) = self.0.start_func {
+            writeln!(f, "    start = {}", func)?;
+        }
         let mut sig_strs = HashMap::new();
         for (sig, sig_data) in self.0.signatures() {
             let arg_tys = sig_data

src/ir/module.rs

@@ -14,6 +14,7 @@ pub struct Module<'a> {
     imports: Vec<Import>,
     exports: Vec<Export>,
     memories: EntityVec<Memory, MemoryData>,
+    pub start_func: Option<Func>,
 }
 
 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
@@ -133,6 +134,7 @@ impl<'a> Module<'a> {
             imports: vec![],
             exports: vec![],
             memories: EntityVec::default(),
+            start_func: None,
         }
     }
 }
@@ -226,15 +228,7 @@ impl<'a> Module<'a> {
     }
 
     pub fn to_wasm_bytes(&self) -> Result<Vec<u8>> {
-        for (func, func_decl) in self.funcs.entries() {
-            log::debug!("Compiling: {}", func);
-            if let Some(body) = func_decl.body() {
-                let comp = backend::WasmBackend::new(body)?;
-                let _ = comp.compile()?;
-            }
-        }
-
-        Ok(vec![])
+        backend::compile(self)
     }
 
     pub fn display<'b>(&'b self) -> ModuleDisplay<'b>