Add support for roundtripping function names.

src/backend/mod.rs

@@ -584,8 +584,8 @@ pub fn compile(module: &Module<'_>) -> anyhow::Result<Vec<u8>> {
     let mut funcs = wasm_encoder::FunctionSection::new();
     for (func, func_decl) in module.funcs.entries().skip(num_func_imports) {
         match func_decl {
-            FuncDecl::Import(_) => anyhow::bail!("Import comes after func with body: {}", func),
-            FuncDecl::Lazy(sig, _) | FuncDecl::Body(sig, _) => {
+            FuncDecl::Import(_, _) => anyhow::bail!("Import comes after func with body: {}", func),
+            FuncDecl::Lazy(sig, _, _) | FuncDecl::Body(sig, _, _) => {
                 funcs.function(sig.index() as u32);
             }
         }
@@ -702,17 +702,17 @@ pub fn compile(module: &Module<'_>) -> anyhow::Result<Vec<u8>> {
         .par_iter()
         .map(|(func, func_decl)| -> Result<FuncOrRawBytes> {
             match func_decl {
-                FuncDecl::Lazy(_, reader) => {
+                FuncDecl::Lazy(_, _name, reader) => {
                     let data = &module.orig_bytes[reader.range()];
                     Ok(FuncOrRawBytes::Raw(data))
                 }
-                FuncDecl::Body(_, body) => {
-                    log::debug!("Compiling {}", func);
+                FuncDecl::Body(_, name, body) => {
+                    log::debug!("Compiling {} \"{}\"", func, name);
                     WasmFuncBackend::new(body)?
                         .compile()
                         .map(|f| FuncOrRawBytes::Func(f))
                 }
-                FuncDecl::Import(_) => unreachable!("Should have skipped imports"),
+                FuncDecl::Import(_, _) => unreachable!("Should have skipped imports"),
             }
         })
         .collect::<Result<Vec<FuncOrRawBytes<'_>>>>()?;
@@ -741,6 +741,14 @@ pub fn compile(module: &Module<'_>) -> anyhow::Result<Vec<u8>> {
     }
     into_mod.section(&data);
 
+    let mut names = wasm_encoder::NameSection::new();
+    let mut func_names = wasm_encoder::NameMap::new();
+    for (func, decl) in module.funcs.entries() {
+        func_names.append(func.index() as u32, decl.name());
+    }
+    names.functions(&func_names);
+    into_mod.section(&names);
+
     Ok(into_mod.finish())
 }
 

src/frontend.rs

@@ -11,7 +11,9 @@ use anyhow::{bail, Result};
 use fxhash::{FxHashMap, FxHashSet};
 use log::trace;
 use std::convert::TryFrom;
-use wasmparser::{BlockType, DataKind, ExternalKind, Parser, Payload, TypeRef};
+use wasmparser::{
+    BlockType, DataKind, ExternalKind, Name, NameSectionReader, Parser, Payload, TypeRef,
+};
 
 pub fn wasm_to_ir(bytes: &[u8]) -> Result<Module<'_>> {
     let mut module = Module::with_orig_bytes(bytes);
@@ -74,7 +76,7 @@ fn handle_payload<'a>(
                     TypeRef::Func(sig_idx) => {
                         let func = module
                             .funcs
-                            .push(FuncDecl::Import(Signature::from(sig_idx)));
+                            .push(FuncDecl::Import(Signature::from(sig_idx), "".to_owned()));
                         *next_func += 1;
                         ImportKind::Func(func)
                     }
@@ -136,17 +138,20 @@ fn handle_payload<'a>(
         Payload::FunctionSection(reader) => {
             for sig_idx in reader {
                 let sig_idx = Signature::from(sig_idx?);
-                module
-                    .funcs
-                    .push(FuncDecl::Body(sig_idx, FunctionBody::default()));
+                module.funcs.push(FuncDecl::Body(
+                    sig_idx,
+                    "".to_owned(),
+                    FunctionBody::default(),
+                ));
             }
         }
         Payload::CodeSectionEntry(body) => {
             let func_idx = Func::new(*next_func);
             *next_func += 1;
 
-            let my_sig = module.funcs[func_idx].sig();
-            module.funcs[func_idx] = FuncDecl::Lazy(my_sig, body);
+            let sig = module.funcs[func_idx].sig();
+            let name = module.funcs[func_idx].name().to_owned();
+            module.funcs[func_idx] = FuncDecl::Lazy(sig, name, body);
         }
         Payload::ExportSection(reader) => {
             for export in reader {
@@ -193,7 +198,21 @@ fn handle_payload<'a>(
                 }
             }
         }
-        Payload::CustomSection { .. } => {}
+        Payload::CustomSection(reader) if reader.name() == "name" => {
+            let name_reader = NameSectionReader::new(reader.data(), reader.data_offset())?;
+            for subsection in name_reader {
+                let subsection = subsection?;
+                match subsection {
+                    Name::Function(names) => {
+                        for name in names {
+                            let name = name?;
+                            module.funcs[Func::new(name.index as usize)].set_name(name.name);
+                        }
+                    }
+                    _ => {}
+                }
+            }
+        }
         Payload::CodeSectionStart { .. } => {}
         Payload::Version { .. } => {}
         Payload::ElementSection(reader) => {

src/ir/display.rs

@@ -209,16 +209,37 @@ impl<'a> Display for ModuleDisplay<'a> {
         }
         for (func, func_decl) in self.0.funcs.entries() {
             match func_decl {
-                FuncDecl::Body(sig, body) => {
-                    writeln!(f, "  {}: {} = # {}", func, sig, sig_strs.get(&sig).unwrap())?;
+                FuncDecl::Body(sig, name, body) => {
+                    writeln!(
+                        f,
+                        "  {} \"{}\": {} = # {}",
+                        func,
+                        name,
+                        sig,
+                        sig_strs.get(&sig).unwrap()
+                    )?;
                     writeln!(f, "{}", body.display("    "))?;
                 }
-                FuncDecl::Lazy(sig, reader) => {
-                    writeln!(f, "  {}: {} = # {}", func, sig, sig_strs.get(&sig).unwrap())?;
+                FuncDecl::Lazy(sig, name, reader) => {
+                    writeln!(
+                        f,
+                        "  {} \"{}\": {} = # {}",
+                        func,
+                        name,
+                        sig,
+                        sig_strs.get(&sig).unwrap()
+                    )?;
                     writeln!(f, "  # raw bytes (length {})", reader.range().len())?;
                 }
-                FuncDecl::Import(sig) => {
-                    writeln!(f, "  {}: {} # {}", func, sig, sig_strs.get(&sig).unwrap())?;
+                FuncDecl::Import(sig, name) => {
+                    writeln!(
+                        f,
+                        "  {} \"{}\": {} # {}",
+                        func,
+                        name,
+                        sig,
+                        sig_strs.get(&sig).unwrap()
+                    )?;
                 }
             }
         }

src/ir/func.rs

@@ -6,15 +6,15 @@ use anyhow::Result;
 
 #[derive(Clone, Debug)]
 pub enum FuncDecl<'a> {
-    Import(Signature),
-    Lazy(Signature, wasmparser::FunctionBody<'a>),
-    Body(Signature, FunctionBody),
+    Import(Signature, String),
+    Lazy(Signature, String, wasmparser::FunctionBody<'a>),
+    Body(Signature, String, FunctionBody),
 }
 
 impl<'a> FuncDecl<'a> {
     pub fn sig(&self) -> Signature {
         match self {
-            FuncDecl::Import(sig) => *sig,
+            FuncDecl::Import(sig, ..) => *sig,
             FuncDecl::Lazy(sig, ..) => *sig,
             FuncDecl::Body(sig, ..) => *sig,
         }
@@ -22,9 +22,9 @@ impl<'a> FuncDecl<'a> {
 
     pub fn parse(&mut self, module: &Module) -> Result<()> {
         match self {
-            FuncDecl::Lazy(sig, body) => {
+            FuncDecl::Lazy(sig, name, body) => {
                 let body = parse_body(module, *sig, body)?;
-                *self = FuncDecl::Body(*sig, body);
+                *self = FuncDecl::Body(*sig, name.clone(), body);
                 Ok(())
             }
             _ => Ok(()),
@@ -33,7 +33,7 @@ impl<'a> FuncDecl<'a> {
 
     pub fn optimize(&mut self) {
         match self {
-            FuncDecl::Body(_, body) => {
+            FuncDecl::Body(_, _, body) => {
                 body.optimize();
             }
             _ => {}
@@ -42,7 +42,7 @@ impl<'a> FuncDecl<'a> {
 
     pub fn convert_to_max_ssa(&mut self) {
         match self {
-            FuncDecl::Body(_, body) => {
+            FuncDecl::Body(_, _, body) => {
                 body.convert_to_max_ssa();
             }
             _ => {}
@@ -51,17 +51,33 @@ impl<'a> FuncDecl<'a> {
 
     pub fn body(&self) -> Option<&FunctionBody> {
         match self {
-            FuncDecl::Body(_, body) => Some(body),
+            FuncDecl::Body(_, _, body) => Some(body),
             _ => None,
         }
     }
 
     pub fn body_mut(&mut self) -> Option<&mut FunctionBody> {
         match self {
-            FuncDecl::Body(_, body) => Some(body),
+            FuncDecl::Body(_, _, body) => Some(body),
             _ => None,
         }
     }
+
+    pub fn name(&self) -> &str {
+        match self {
+            FuncDecl::Body(_, name, _) | FuncDecl::Lazy(_, name, _) | FuncDecl::Import(_, name) => {
+                &name[..]
+            }
+        }
+    }
+
+    pub fn set_name(&mut self, new_name: &str) {
+        match self {
+            FuncDecl::Body(_, name, _) | FuncDecl::Lazy(_, name, _) | FuncDecl::Import(_, name) => {
+                *name = new_name.to_owned()
+            }
+        }
+    }
 }
 
 #[derive(Clone, Debug, Default)]