Introduce ZkasmEnvironment

This PR forks DummyEnvironment that we used before, as we will need to change it to enable memory operations.
At this point, there are no changes to the environment and this should be a no-op.

In the past, we relied on DummyEnvironment which is only useful in testing, but in reality, we need a dedicated environment suited for ZKASM machine.

cranelift/filetests/src/test_zkasm.rs

@@ -12,7 +12,7 @@ mod tests {
     use cranelift_codegen::ir::ExternalName;
     use cranelift_codegen::isa::zkasm;
     use cranelift_codegen::{settings, FinalizedMachReloc, FinalizedRelocTarget};
-    use cranelift_wasm::{translate_module, DummyEnvironment};
+    use cranelift_wasm::{translate_module, ZkasmEnvironment};
 
     fn setup() {
         let _ = env_logger::builder().is_test(true).try_init();
@@ -142,20 +142,20 @@ mod tests {
         let isa = isa_builder
             .finish(settings::Flags::new(flag_builder))
             .unwrap();
-        let mut dummy_environ = DummyEnvironment::new(isa.frontend_config());
-        translate_module(wasm_module, &mut dummy_environ).unwrap();
+        let mut zkasm_environ = ZkasmEnvironment::new(isa.frontend_config());
+        translate_module(wasm_module, &mut zkasm_environ).unwrap();
 
         let mut program: Vec<String> = Vec::new();
-        let start_func = dummy_environ
+        let start_func = zkasm_environ
             .info
             .start_func
             .expect("Must have a start function");
         // TODO: Preamble should be generated by a linker and/or clift itself.
         program.append(&mut generate_preamble(start_func.index()));
 
-        let num_func_imports = dummy_environ.get_num_func_imports();
+        let num_func_imports = zkasm_environ.get_num_func_imports();
         let mut context = cranelift_codegen::Context::new();
-        for (def_index, func) in dummy_environ.info.function_bodies.iter() {
+        for (def_index, func) in zkasm_environ.info.function_bodies.iter() {
             let func_index = num_func_imports + def_index.index();
             program.push(format!("function_{}:", func_index));
 

cranelift/wasm/src/environ/mod.rs

@@ -3,10 +3,12 @@
 mod dummy;
 #[macro_use]
 mod spec;
+mod zkasm;
 
 pub use crate::environ::dummy::{
     DummyEnvironment, DummyFuncEnvironment, DummyModuleInfo, ExpectedReachability,
 };
 pub use crate::environ::spec::{
     FuncEnvironment, GlobalVariable, ModuleEnvironment, TargetEnvironment,
 };
+pub use crate::environ::zkasm::{ZkasmEnvironment, ZkasmFuncEnvironment, ZkasmModuleInfo};