make backtrace collection a Config field rather than a cargo feature (b…

…ytecodealliance#4183)

* sorta working in runtime

* wasmtime-runtime: get rid of wasm-backtrace feature

* wasmtime: factor to make backtraces recording optional. not configurable yet

* get rid of wasm-backtrace features

* trap tests: now a Trap optionally contains backtrace

* eliminate wasm-backtrace feature

* code review fixes

* ci: no more wasm-backtrace feature

* c_api: backtraces always enabled

* config: unwind required by backtraces and ref types

* plumbed

* test that disabling backtraces works

* code review comments

* fuzzing generator: wasm_backtrace is a runtime config now

* doc fix

.github/workflows/main.yml

@@ -136,9 +136,8 @@ jobs:
     - run: cargo check -p wasmtime --no-default-features --features async
     - run: cargo check -p wasmtime --no-default-features --features pooling-allocator
     - run: cargo check -p wasmtime --no-default-features --features cranelift
-    - run: cargo check -p wasmtime --no-default-features --features wasm-backtrace
     - run: cargo check -p wasmtime --no-default-features --features component-model
-    - run: cargo check -p wasmtime --no-default-features --features cranelift,wat,async,cache,wasm-backtrace
+    - run: cargo check -p wasmtime --no-default-features --features cranelift,wat,async,cache
     - run: cargo check --features component-model
 
     # Check that benchmarks of the cranelift project build

Cargo.toml

@@ -98,7 +98,6 @@ default = [
   "wasi-nn",
   "pooling-allocator",
   "memory-init-cow",
-  "wasm-backtrace",
 ]
 jitdump = ["wasmtime/jitdump"]
 vtune = ["wasmtime/vtune"]
@@ -108,7 +107,6 @@ memory-init-cow = ["wasmtime/memory-init-cow", "wasmtime-cli-flags/memory-init-c
 pooling-allocator = ["wasmtime/pooling-allocator", "wasmtime-cli-flags/pooling-allocator"]
 all-arch = ["wasmtime/all-arch"]
 posix-signals-on-macos = ["wasmtime/posix-signals-on-macos"]
-wasm-backtrace = ["wasmtime/wasm-backtrace", "wasmtime-cli-flags/wasm-backtrace"]
 component-model = ["wasmtime/component-model", "wasmtime-wast/component-model", "wasmtime-cli-flags/component-model"]
 
 # Stub feature that does nothing, for Cargo-features compatibility: the new

crates/c-api/Cargo.toml

@@ -20,7 +20,7 @@ doctest = false
 env_logger = "0.9"
 anyhow = "1.0"
 once_cell = "1.3"
-wasmtime = { path = "../wasmtime", default-features = false, features = ['cranelift', 'wasm-backtrace'] }
+wasmtime = { path = "../wasmtime", default-features = false, features = ['cranelift'] }
 wasmtime-c-api-macros = { path = "macros" }
 
 # Optional dependency for the `wat2wasm` API

crates/c-api/src/trap.rs

@@ -64,7 +64,13 @@ pub extern "C" fn wasm_trap_message(trap: &wasm_trap_t, out: &mut wasm_message_t
 
 #[no_mangle]
 pub extern "C" fn wasm_trap_origin(raw: &wasm_trap_t) -> Option<Box<wasm_frame_t>> {
-    if raw.trap.trace().len() > 0 {
+    if raw
+        .trap
+        .trace()
+        .expect("backtraces are always enabled")
+        .len()
+        > 0
+    {
         Some(Box::new(wasm_frame_t {
             trap: raw.trap.clone(),
             idx: 0,
@@ -78,7 +84,11 @@ pub extern "C" fn wasm_trap_origin(raw: &wasm_trap_t) -> Option<Box<wasm_frame_t
 
 #[no_mangle]
 pub extern "C" fn wasm_trap_trace(raw: &wasm_trap_t, out: &mut wasm_frame_vec_t) {
-    let vec = (0..raw.trap.trace().len())
+    let vec = (0..raw
+        .trap
+        .trace()
+        .expect("backtraces are always enabled")
+        .len())
         .map(|idx| {
             Some(Box::new(wasm_frame_t {
                 trap: raw.trap.clone(),
@@ -128,15 +138,15 @@ pub extern "C" fn wasmtime_trap_exit_status(raw: &wasm_trap_t, status: &mut i32)
 
 #[no_mangle]
 pub extern "C" fn wasm_frame_func_index(frame: &wasm_frame_t) -> u32 {
-    frame.trap.trace()[frame.idx].func_index()
+    frame.trap.trace().expect("backtraces are always enabled")[frame.idx].func_index()
 }
 
 #[no_mangle]
 pub extern "C" fn wasmtime_frame_func_name(frame: &wasm_frame_t) -> Option<&wasm_name_t> {
     frame
         .func_name
         .get_or_init(|| {
-            frame.trap.trace()[frame.idx]
+            frame.trap.trace().expect("backtraces are always enabled")[frame.idx]
                 .func_name()
                 .map(|s| wasm_name_t::from(s.to_string().into_bytes()))
         })
@@ -148,7 +158,7 @@ pub extern "C" fn wasmtime_frame_module_name(frame: &wasm_frame_t) -> Option<&wa
     frame
         .module_name
         .get_or_init(|| {
-            frame.trap.trace()[frame.idx]
+            frame.trap.trace().expect("backtraces are always enabled")[frame.idx]
                 .module_name()
                 .map(|s| wasm_name_t::from(s.to_string().into_bytes()))
         })
@@ -157,7 +167,7 @@ pub extern "C" fn wasmtime_frame_module_name(frame: &wasm_frame_t) -> Option<&wa
 
 #[no_mangle]
 pub extern "C" fn wasm_frame_func_offset(frame: &wasm_frame_t) -> usize {
-    frame.trap.trace()[frame.idx]
+    frame.trap.trace().expect("backtraces are always enabled")[frame.idx]
         .func_offset()
         .unwrap_or(usize::MAX)
 }
@@ -169,7 +179,7 @@ pub extern "C" fn wasm_frame_instance(_arg1: *const wasm_frame_t) -> *mut wasm_i
 
 #[no_mangle]
 pub extern "C" fn wasm_frame_module_offset(frame: &wasm_frame_t) -> usize {
-    frame.trap.trace()[frame.idx]
+    frame.trap.trace().expect("backtraces are always enabled")[frame.idx]
         .module_offset()
         .unwrap_or(usize::MAX)
 }

crates/cli-flags/Cargo.toml

@@ -25,5 +25,4 @@ default = [
 ]
 pooling-allocator = []
 memory-init-cow = []
-wasm-backtrace = []
 component-model = []

crates/cli-flags/src/lib.rs

@@ -346,9 +346,7 @@ impl CommonOptions {
             config.wasm_bulk_memory(enable);
         }
         if let Some(enable) = reference_types {
-            #[cfg(feature = "wasm-backtrace")]
             config.wasm_reference_types(enable);
-            drop(enable); // suppress unused warnings
         }
         if let Some(enable) = multi_value {
             config.wasm_multi_value(enable);

crates/fuzzing/src/generators.rs

@@ -213,6 +213,7 @@ pub struct WasmtimeConfig {
     codegen: CodegenSettings,
     padding_between_functions: Option<u16>,
     generate_address_map: bool,
+    wasm_backtraces: bool,
 }
 
 /// Configuration for linear memories in Wasmtime.
@@ -387,6 +388,7 @@ impl Config {
             .wasm_multi_memory(self.module_config.config.max_memories > 1)
             .wasm_simd(self.module_config.config.simd_enabled)
             .wasm_memory64(self.module_config.config.memory64_enabled)
+            .wasm_backtrace(self.wasmtime.wasm_backtraces)
             .cranelift_nan_canonicalization(self.wasmtime.canonicalize_nans)
             .cranelift_opt_level(self.wasmtime.opt_level.to_wasmtime())
             .consume_fuel(self.wasmtime.consume_fuel)

crates/runtime/Cargo.toml

@@ -22,7 +22,7 @@ indexmap = "1.0.2"
 thiserror = "1.0.4"
 more-asserts = "0.2.1"
 cfg-if = "1.0"
-backtrace = { version = "0.3.61", optional = true }
+backtrace = { version = "0.3.61" }
 rand = "0.8.3"
 anyhow = "1.0.38"
 memfd = { version = "0.4.1", optional = true }
@@ -44,7 +44,6 @@ maintenance = { status = "actively-developed" }
 
 [features]
 memory-init-cow = ['memfd']
-wasm-backtrace = ["backtrace"]
 
 async = ["wasmtime-fiber"]
 

crates/runtime/src/externref.rs

@@ -704,7 +704,6 @@ impl VMExternRefActivationsTable {
         }
     }
 
-    #[cfg_attr(not(feature = "wasm-backtrace"), allow(dead_code))]
     fn insert_precise_stack_root(
         precise_stack_roots: &mut HashSet<VMExternRefWithTraits>,
         root: NonNull<VMExternData>,
@@ -867,7 +866,6 @@ impl<T> std::ops::DerefMut for DebugOnly<T> {
 ///
 /// Additionally, you must have registered the stack maps for every Wasm module
 /// that has frames on the stack with the given `stack_maps_registry`.
-#[cfg_attr(not(feature = "wasm-backtrace"), allow(unused_mut, unused_variables))]
 pub unsafe fn gc(
     module_info_lookup: &dyn ModuleInfoLookup,
     externref_activations_table: &mut VMExternRefActivationsTable,
@@ -895,7 +893,6 @@ pub unsafe fn gc(
         None => {
             if cfg!(debug_assertions) {
                 // Assert that there aren't any Wasm frames on the stack.
-                #[cfg(feature = "wasm-backtrace")]
                 backtrace::trace(|frame| {
                     assert!(module_info_lookup.lookup(frame.ip() as usize).is_none());
                     true
@@ -937,7 +934,6 @@ pub unsafe fn gc(
         });
     }
 
-    #[cfg(feature = "wasm-backtrace")]
     backtrace::trace(|frame| {
         let pc = frame.ip() as usize;
         let sp = frame.sp() as usize;

crates/runtime/src/libcalls.rs

@@ -507,7 +507,7 @@ pub unsafe extern "C" fn memory_atomic_notify(
         // just to be sure.
         let addr_to_check = addr.checked_add(4).unwrap();
         validate_atomic_addr(instance, memory, addr_to_check).and_then(|()| {
-            Err(Trap::User(anyhow::anyhow!(
+            Err(Trap::user(anyhow::anyhow!(
                 "unimplemented: wasm atomics (fn memory_atomic_notify) unsupported",
             )))
         })
@@ -534,7 +534,7 @@ pub unsafe extern "C" fn memory_atomic_wait32(
         // but we still double-check
         let addr_to_check = addr.checked_add(4).unwrap();
         validate_atomic_addr(instance, memory, addr_to_check).and_then(|()| {
-            Err(Trap::User(anyhow::anyhow!(
+            Err(Trap::user(anyhow::anyhow!(
                 "unimplemented: wasm atomics (fn memory_atomic_wait32) unsupported",
             )))
         })
@@ -561,7 +561,7 @@ pub unsafe extern "C" fn memory_atomic_wait64(
         // but we still double-check
         let addr_to_check = addr.checked_add(8).unwrap();
         validate_atomic_addr(instance, memory, addr_to_check).and_then(|()| {
-            Err(Trap::User(anyhow::anyhow!(
+            Err(Trap::user(anyhow::anyhow!(
                 "unimplemented: wasm atomics (fn memory_atomic_wait64) unsupported",
             )))
         })