Don't re-parse wasm for debuginfo (#2085)

* Don't re-parse wasm for debuginfo

This commit updates debuginfo parsing to happen during the main
translation of the original wasm module. This avoid re-parsing the wasm
module twice (at least the section-level headers). Additionally this
ties debuginfo directly to a `ModuleTranslation` which makes it easier
to process debuginfo for nested modules in the upcoming module linking
proposal.

The changes here are summarized by taking the `read_debuginfo` function
and merging it with the main module translation that happens which is
driven by cranelift. Some new hooks were added to the module environment
trait to support this, but most of it was integrating with existing hooks.

* Fix tests in debug crate

cranelift/wasm/src/sections_translator.rs

@@ -13,7 +13,7 @@ use crate::translation_utils::{
     tabletype_to_type, type_to_type, DataIndex, ElemIndex, FuncIndex, Global, GlobalIndex,
     GlobalInit, Memory, MemoryIndex, SignatureIndex, Table, TableElementType, TableIndex,
 };
-use crate::{wasm_unsupported, HashMap};
+use crate::wasm_unsupported;
 use core::convert::TryFrom;
 use core::convert::TryInto;
 use cranelift_codegen::ir::immediates::V128Imm;
@@ -26,8 +26,8 @@ use wasmparser::{
     self, Data, DataKind, DataSectionReader, Element, ElementItem, ElementItems, ElementKind,
     ElementSectionReader, Export, ExportSectionReader, ExternalKind, FunctionSectionReader,
     GlobalSectionReader, GlobalType, ImportSectionEntryType, ImportSectionReader,
-    MemorySectionReader, MemoryType, NameSectionReader, Naming, NamingReader, Operator,
-    TableSectionReader, Type, TypeDef, TypeSectionReader,
+    MemorySectionReader, MemoryType, NameSectionReader, Naming, Operator, TableSectionReader, Type,
+    TypeDef, TypeSectionReader,
 };
 
 /// Parses the Type section of the wasm module.
@@ -404,53 +404,40 @@ pub fn parse_data_section<'data>(
 
 /// Parses the Name section of the wasm module.
 pub fn parse_name_section<'data>(
-    mut names: NameSectionReader<'data>,
+    names: NameSectionReader<'data>,
     environ: &mut dyn ModuleEnvironment<'data>,
 ) -> WasmResult<()> {
-    while let Ok(subsection) = names.read() {
-        match subsection {
-            wasmparser::Name::Function(function_subsection) => {
-                if let Some(function_names) = function_subsection
-                    .get_map()
-                    .ok()
-                    .and_then(parse_function_name_subsection)
-                {
-                    for (index, name) in function_names {
-                        environ.declare_func_name(index, name)?;
+    for subsection in names {
+        match subsection? {
+            wasmparser::Name::Function(f) => {
+                let mut names = f.get_map()?;
+                for _ in 0..names.get_count() {
+                    let Naming { index, name } = names.read()?;
+                    // We reserve `u32::MAX` for our own use in cranelift-entity.
+                    if index != u32::max_value() {
+                        environ.declare_func_name(FuncIndex::from_u32(index), name);
                     }
                 }
             }
             wasmparser::Name::Module(module) => {
-                if let Ok(name) = module.get_name() {
-                    environ.declare_module_name(name)?;
+                let name = module.get_name()?;
+                environ.declare_module_name(name);
+            }
+            wasmparser::Name::Local(l) => {
+                let mut reader = l.get_function_local_reader()?;
+                for _ in 0..reader.get_count() {
+                    let f = reader.read()?;
+                    if f.func_index == u32::max_value() {
+                        continue;
+                    }
+                    let mut map = f.get_map()?;
+                    for _ in 0..map.get_count() {
+                        let Naming { index, name } = map.read()?;
+                        environ.declare_local_name(FuncIndex::from_u32(f.func_index), index, name)
+                    }
                 }
             }
-            wasmparser::Name::Local(_) => {}
-        };
+        }
     }
     Ok(())
 }
-
-fn parse_function_name_subsection(
-    mut naming_reader: NamingReader<'_>,
-) -> Option<HashMap<FuncIndex, &str>> {
-    let mut function_names = HashMap::new();
-    for _ in 0..naming_reader.get_count() {
-        let Naming { index, name } = naming_reader.read().ok()?;
-        if index == std::u32::MAX {
-            // We reserve `u32::MAX` for our own use in cranelift-entity.
-            return None;
-        }
-
-        if function_names
-            .insert(FuncIndex::from_u32(index), name)
-            .is_some()
-        {
-            // If the function index has been previously seen, then we
-            // break out of the loop and early return `None`, because these
-            // should be unique.
-            return None;
-        }
-    }
-    Some(function_names)
-}