Compile a simple function (#2)

* Implement basics.

* Execute code

* Add wasm2wat test cases.

* abi_loc_for_arg for stack.

* Assert that sp_depth is 0 at the epilogue

* Do 32bit add.

* Assert that RAX can be used as a scratch register

* Reuse assembler.

* Align stack slots.

src/translate_sections.rs

@@ -7,6 +7,7 @@ use wasmparser::{
     GlobalSectionReader, GlobalType, Import, ImportSectionEntryType, ImportSectionReader,
     MemorySectionReader, MemoryType, Operator, TableSectionReader, Type, TypeSectionReader,
 };
+use backend::{CodeGenSession, TranslatedCodeSection};
 
 /// Parses the Type section of the wasm module.
 pub fn type_(types: TypeSectionReader) -> Result<(), Error> {
@@ -79,11 +80,12 @@ pub fn element(elements: ElementSectionReader) -> Result<(), Error> {
 }
 
 /// Parses the Code section of the wasm module.
-pub fn code(code: CodeSectionReader) -> Result<(), Error> {
+pub fn code(code: CodeSectionReader) -> Result<TranslatedCodeSection, Error> {
+    let mut session = CodeGenSession::new();
     for body in code {
-        function_body::translate(&body?)?;
+        function_body::translate(&mut session, &body?)?;
     }
-    Ok(())
+    Ok(session.into_translated_code_section()?)
 }
 
 /// Parses the Data section of the wasm module.