Generate debug info for LLDB/GDB (#50)

* Transform DWARF sections into native format for wasm2obj and wasmtime.

Generate DWARF sections based on WASM DWARF.
Ignore some of debug_info/debug_line for dead code.

* Fix test

lib/runtime/src/instance.rs

@@ -4,6 +4,7 @@
 
 use crate::export::Export;
 use crate::imports::Imports;
+use crate::jit_int::GdbJitImageRegistration;
 use crate::memory::LinearMemory;
 use crate::mmap::Mmap;
 use crate::signalhandlers::{wasmtime_init_eager, wasmtime_init_finish};
@@ -215,6 +216,9 @@ pub(crate) struct Instance {
     /// Hosts can store arbitrary per-instance information here.
     host_state: Box<dyn Any>,
 
+    /// Optional image of JIT'ed code for debugger registration.
+    dbg_jit_registration: Option<Rc<GdbJitImageRegistration>>,
+
     /// Additional context used by compiled wasm code. This field is last, and
     /// represents a dynamically-sized array that extends beyond the nominal
     /// end of the struct (similar to a flexible array member).
@@ -623,6 +627,7 @@ impl InstanceHandle {
         imports: Imports,
         data_initializers: &[DataInitializer<'_>],
         vmshared_signatures: BoxedSlice<SignatureIndex, VMSharedSignatureIndex>,
+        dbg_jit_registration: Option<Rc<GdbJitImageRegistration>>,
         host_state: Box<dyn Any>,
     ) -> Result<Self, InstantiationError> {
         let mut tables = create_tables(&module);
@@ -664,6 +669,7 @@ impl InstanceHandle {
                 memories,
                 tables,
                 finished_functions,
+                dbg_jit_registration,
                 host_state,
                 vmctx: VMContext {},
             };