Parallelize the compilation loop with Rayon (#58)

lib/environ/Cargo.toml

@@ -19,6 +19,7 @@ cast = { version = "0.2.2", default-features = false }
 failure = { version = "0.1.3", default-features = false }
 failure_derive = { version = "0.1.3", default-features = false }
 indexmap = "1.0.2"
+rayon = "1.0"
 
 [features]
 default = ["std"]

lib/environ/src/cranelift.rs

@@ -13,6 +13,7 @@ use cranelift_codegen::isa;
 use cranelift_codegen::Context;
 use cranelift_entity::PrimaryMap;
 use cranelift_wasm::{DefinedFuncIndex, FuncIndex, FuncTranslator};
+use rayon::prelude::{IntoParallelRefIterator, ParallelIterator};
 use std::vec::Vec;
 
 /// Implementation of a relocation sink that just saves all the information for later
@@ -89,8 +90,13 @@ pub fn compile_module<'data, 'module>(
 ) -> Result<(Compilation, Relocations), CompileError> {
     let mut functions = PrimaryMap::with_capacity(function_body_inputs.len());
     let mut relocations = PrimaryMap::with_capacity(function_body_inputs.len());
-    for (i, input) in function_body_inputs.into_iter() {
-        let func_index = module.func_index(i);
+
+    function_body_inputs
+        .into_iter()
+        .collect::<Vec<(DefinedFuncIndex, &&'data [u8])>>()
+        .par_iter()
+        .map(|(i, input)| {
+            let func_index = module.func_index(*i);
             let mut context = Context::new();
             context.func.name = get_func_name(func_index);
             context.func.signature = module.signatures[module.functions[func_index]].clone();
@@ -110,9 +116,14 @@ pub fn compile_module<'data, 'module>(
             context
                 .compile_and_emit(isa, &mut code_buf, &mut reloc_sink, &mut trap_sink)
                 .map_err(CompileError::Codegen)?;
-        functions.push(code_buf);
-        relocations.push(reloc_sink.func_relocs);
-    }
+            Ok((code_buf, reloc_sink.func_relocs))
+        })
+        .collect::<Result<Vec<_>, CompileError>>()?
+        .into_iter()
+        .for_each(|(function, relocs)| {
+            functions.push(function);
+            relocations.push(relocs);
+        });
 
     // TODO: Reorganize where we create the Vec for the resolved imports.
     Ok((Compilation::new(functions), relocations))