Merge pull request #641 from data-pup/instantiate_empty

Instantiate empty module

crates/fuzzing/Cargo.toml

@@ -19,3 +19,6 @@ log = "0.4.8"
 wasmparser = "0.42.1"
 wasmprinter = "0.2.0"
 wasmtime-jit = { path = "../jit" }
+
+[dev-dependencies]
+wat = "1.0"

crates/fuzzing/tests/regressions.rs

@@ -7,3 +7,9 @@
 
 #[allow(unused_imports)] // Until we actually have some regression tests...
 use wasmtime_fuzzing::*;
+
+#[test]
+fn instantiate_empty_module() {
+    let data = wat::parse_str(include_str!("./regressions/empty.wat")).unwrap();
+    oracles::instantiate(&data, wasmtime_jit::CompilationStrategy::Auto);
+}

crates/fuzzing/tests/regressions/empty.wat

@@ -0,0 +1 @@
+(module)

crates/jit/src/compiler.rs

@@ -156,7 +156,8 @@ impl Compiler {
 
         let dbg = if let Some(debug_data) = debug_data {
             let target_config = self.isa.frontend_config();
-            let triple = self.isa.triple().clone();
+            let ofs = VMOffsets::new(target_config.pointer_bytes(), &module);
+            if ofs.num_defined_memories > 0 {
                 let mut funcs = Vec::new();
                 for (i, allocated) in allocated_functions.into_iter() {
                     let ptr = (*allocated) as *const u8;
@@ -164,7 +165,6 @@ impl Compiler {
                     funcs.push((ptr, body_len));
                 }
                 let module_vmctx_info = {
-                let ofs = VMOffsets::new(target_config.pointer_bytes(), &module);
                     let memory_offset =
                         ofs.vmctx_vmmemory_definition_base(DefinedMemoryIndex::new(0)) as i64;
                     ModuleVmctxInfo {
@@ -173,7 +173,7 @@ impl Compiler {
                     }
                 };
                 let bytes = emit_debugsections_image(
-                triple,
+                    self.isa.triple().clone(),
                     &target_config,
                     &debug_data,
                     &module_vmctx_info,
@@ -185,6 +185,9 @@ impl Compiler {
                 Some(bytes)
             } else {
                 None
+            }
+        } else {
+            None
         };
 
         let jt_offsets = compilation.get_jt_offsets();