Revert "Stack switching: Infrastructure and runtime support (#10388)" (#10938)

This reverts commit 63d482c.

Author: alexcrichton

.github/workflows/main.yml

@@ -371,9 +371,6 @@ jobs:
               -p wasmtime --no-default-features --features threads
               -p wasmtime --no-default-features --features runtime,threads
               -p wasmtime --no-default-features --features cranelift,threads
-              -p wasmtime --no-default-features --features stack-switching
-              -p wasmtime --no-default-features --features cranelift,stack-switching
-              -p wasmtime --no-default-features --features runtime,stack-switching
               -p wasmtime --features incremental-cache
               -p wasmtime --features profile-pulley
               -p wasmtime --all-features

Cargo.toml

@@ -431,7 +431,6 @@ default = [
   "gc",
   "gc-drc",
   "gc-null",
-  "stack-switching",
   "winch",
   "pulley",
 
@@ -490,7 +489,6 @@ gc = ["wasmtime-cli-flags/gc", "wasmtime/gc"]
 gc-drc = ["gc", "wasmtime/gc-drc", "wasmtime-cli-flags/gc-drc"]
 gc-null = ["gc", "wasmtime/gc-null", "wasmtime-cli-flags/gc-null"]
 pulley = ["wasmtime-cli-flags/pulley"]
-stack-switching = ["wasmtime/stack-switching", "wasmtime-cli-flags/stack-switching"]
 
 # CLI subcommands for the `wasmtime` executable. See `wasmtime $cmd --help`
 # for more information on each subcommand.

crates/c-api/include/wasmtime/config.h

@@ -250,14 +250,6 @@ WASMTIME_CONFIG_PROP(void, wasm_wide_arithmetic, bool)
 
 #ifdef WASMTIME_FEATURE_COMPILER
 
-/**
- * \brief Configures whether the WebAssembly stack switching
- * proposal is enabled.
- *
- * This setting is `false` by default.
- */
-WASMTIME_CONFIG_PROP(void, wasm_stack_switching, bool)
-
 /**
  * \brief Configures how JIT code will be compiled.
  *

crates/c-api/src/config.rs

@@ -140,11 +140,6 @@ pub extern "C" fn wasmtime_config_wasm_memory64_set(c: &mut wasm_config_t, enabl
     c.config.wasm_memory64(enable);
 }
 
-#[unsafe(no_mangle)]
-pub extern "C" fn wasmtime_config_wasm_stack_switching_set(c: &mut wasm_config_t, enable: bool) {
-    c.config.wasm_stack_switching(enable);
-}
-
 #[unsafe(no_mangle)]
 #[cfg(any(feature = "cranelift", feature = "winch"))]
 pub extern "C" fn wasmtime_config_strategy_set(

crates/cli-flags/Cargo.toml

@@ -39,4 +39,3 @@ gc-null = ["gc", "wasmtime/gc-null"]
 threads = ["wasmtime/threads"]
 memory-protection-keys = ["wasmtime/memory-protection-keys"]
 pulley = ["wasmtime/pulley"]
-stack-switching = ["wasmtime/stack-switching"]

crates/cli-flags/src/lib.rs

@@ -377,8 +377,6 @@ wasmtime_option_group! {
         pub component_model_error_context: Option<bool>,
         /// Configure support for the function-references proposal.
         pub function_references: Option<bool>,
-        /// Configure support for the stack-switching proposal.
-        pub stack_switching: Option<bool>,
         /// Configure support for the GC proposal.
         pub gc: Option<bool>,
         /// Configure support for the custom-page-sizes proposal.
@@ -820,23 +818,6 @@ impl CommonOptions {
             config.native_unwind_info(enable);
         }
 
-        // async_stack_size enabled by either async or stack-switching, so
-        // cannot directly use match_feature!
-        #[cfg(any(feature = "async", feature = "stack-switching"))]
-        {
-            if let Some(size) = self.wasm.async_stack_size {
-                config.async_stack_size(size);
-            }
-        }
-        #[cfg(not(any(feature = "async", feature = "stack-switching")))]
-        {
-            if let Some(_size) = self.wasm.async_stack_size {
-                anyhow::bail!(concat!(
-                    "support for async/stack-switching disabled at compile time"
-                ));
-            }
-        }
-
         match_feature! {
             ["pooling-allocator" : self.opts.pooling_allocator.or(pooling_allocator_default)]
             enable => {
@@ -942,6 +923,11 @@ impl CommonOptions {
             );
         }
 
+        match_feature! {
+            ["async" : self.wasm.async_stack_size]
+            size => config.async_stack_size(size),
+            _ => err,
+        }
         match_feature! {
             ["async" : self.wasm.async_stack_zeroing]
             enable => config.async_stack_zeroing(enable),
@@ -954,7 +940,7 @@ impl CommonOptions {
             // If `-Wasync-stack-size` isn't passed then automatically adjust it
             // to the wasm stack size provided here too. That prevents the need
             // to pass both when one can generally be inferred from the other.
-            #[cfg(any(feature = "async", feature = "stack-switching"))]
+            #[cfg(feature = "async")]
             if self.wasm.async_stack_size.is_none() {
                 const DEFAULT_HOST_STACK: usize = 512 << 10;
                 config.async_stack_size(max + DEFAULT_HOST_STACK);
@@ -997,9 +983,6 @@ impl CommonOptions {
         if let Some(enable) = self.wasm.memory64.or(all) {
             config.wasm_memory64(enable);
         }
-        if let Some(enable) = self.wasm.stack_switching {
-            config.wasm_stack_switching(enable);
-        }
         if let Some(enable) = self.wasm.custom_page_sizes.or(all) {
             config.wasm_custom_page_sizes(enable);
         }
@@ -1040,7 +1023,6 @@ impl CommonOptions {
             ("gc", gc, wasm_gc)
             ("gc", reference_types, wasm_reference_types)
             ("gc", function_references, wasm_function_references)
-            ("stack-switching", stack_switching, wasm_stack_switching)
         }
         Ok(())
     }

crates/cranelift/Cargo.toml

@@ -46,5 +46,4 @@ wmemcheck = ["wasmtime-environ/wmemcheck"]
 gc = ["wasmtime-environ/gc"]
 gc-drc = ["gc", "wasmtime-environ/gc-drc"]
 gc-null = ["gc", "wasmtime-environ/gc-null"]
-stack-switching = []
 threads = ["wasmtime-environ/threads"]

crates/cranelift/src/func_environ.rs

@@ -3793,17 +3793,3 @@ fn index_type_to_ir_type(index_type: IndexType) -> ir::Type {
         IndexType::I64 => I64,
     }
 }
-
-/// TODO(10248) This is removed in the next stack switching PR. It stops the
-/// compiler from complaining about the stack switching libcalls being dead
-/// code.
-#[cfg(feature = "stack-switching")]
-#[allow(
-    dead_code,
-    reason = "Dummy function to supress more dead code warnings"
-)]
-pub fn use_stack_switching_libcalls() {
-    let _ = BuiltinFunctions::cont_new;
-    let _ = BuiltinFunctions::table_grow_cont_obj;
-    let _ = BuiltinFunctions::table_fill_cont_obj;
-}

crates/cranelift/src/func_environ/gc/enabled.rs

@@ -153,12 +153,7 @@ fn read_field_at_addr(
                         .call(get_interned_func_ref, &[vmctx, func_ref_id, expected_ty]);
                     builder.func.dfg.first_result(call_inst)
                 }
-                WasmHeapTopType::Cont => {
-                    // TODO(#10248) GC integration for stack switching
-                    return Err(wasmtime_environ::WasmError::Unsupported(
-                        "Stack switching feature not compatbile with GC, yet".to_string(),
-                    ));
-                }
+                WasmHeapTopType::Cont => todo!(), // FIXME: #10248 stack switching support.
             },
         },
     };
@@ -1037,8 +1032,6 @@ pub fn translate_ref_test(
         | WasmHeapType::NoExtern
         | WasmHeapType::Func
         | WasmHeapType::NoFunc
-        | WasmHeapType::Cont
-        | WasmHeapType::NoCont
         | WasmHeapType::I31 => unreachable!("handled top, bottom, and i31 types above"),
 
         // For these abstract but non-top and non-bottom types, we check the
@@ -1093,12 +1086,8 @@ pub fn translate_ref_test(
 
             func_env.is_subtype(builder, actual_shared_ty, expected_shared_ty)
         }
-        WasmHeapType::ConcreteCont(_) => {
-            // TODO(#10248) GC integration for stack switching
-            return Err(wasmtime_environ::WasmError::Unsupported(
-                "Stack switching feature not compatbile with GC, yet".to_string(),
-            ));
-        }
+
+        WasmHeapType::Cont | WasmHeapType::ConcreteCont(_) | WasmHeapType::NoCont => todo!(), // FIXME: #10248 stack switching support.
     };
     builder.ins().jump(continue_block, &[result.into()]);
 
@@ -1420,9 +1409,8 @@ impl FuncEnvironment<'_> {
             WasmHeapType::Func | WasmHeapType::ConcreteFunc(_) | WasmHeapType::NoFunc => {
                 unreachable!()
             }
-            WasmHeapType::Cont | WasmHeapType::ConcreteCont(_) | WasmHeapType::NoCont => {
-                unreachable!()
-            }
+
+            WasmHeapType::Cont | WasmHeapType::ConcreteCont(_) | WasmHeapType::NoCont => todo!(), // FIXME: #10248 stack switching support.
         };
 
         match (ty.nullable, might_be_i31) {

crates/cranelift/src/lib.rs

@@ -61,10 +61,6 @@ pub const TRAP_HEAP_MISALIGNED: TrapCode =
     TrapCode::unwrap_user(Trap::HeapMisaligned as u8 + TRAP_OFFSET);
 pub const TRAP_TABLE_OUT_OF_BOUNDS: TrapCode =
     TrapCode::unwrap_user(Trap::TableOutOfBounds as u8 + TRAP_OFFSET);
-pub const TRAP_UNHANDLED_TAG: TrapCode =
-    TrapCode::unwrap_user(Trap::UnhandledTag as u8 + TRAP_OFFSET);
-pub const TRAP_CONTINUATION_ALREADY_CONSUMED: TrapCode =
-    TrapCode::unwrap_user(Trap::ContinuationAlreadyConsumed as u8 + TRAP_OFFSET);
 pub const TRAP_CAST_FAILURE: TrapCode =
     TrapCode::unwrap_user(Trap::CastFailure as u8 + TRAP_OFFSET);
 
@@ -206,11 +202,7 @@ fn reference_type(wasm_ht: WasmHeapType, pointer_type: ir::Type) -> ir::Type {
     match wasm_ht.top() {
         WasmHeapTopType::Func => pointer_type,
         WasmHeapTopType::Any | WasmHeapTopType::Extern => ir::types::I32,
-        WasmHeapTopType::Cont =>
-        // TODO(10248) This is added in a follow-up PR
-        {
-            unimplemented!("codegen for stack switching types not implemented, yet")
-        }
+        WasmHeapTopType::Cont => todo!(), // FIXME: #10248 stack switching support.
     }
 }