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Unconditionally setup tasks for resource destructors #14158

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11 changes: 11 additions & 0 deletions crates/cranelift/src/alias_region.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -932,6 +932,17 @@ where
}
}

/// The Cranelift type of a pointer on the target being compiled for.
pub fn pointer_type(&self) -> ir::Type {
self.pointer_type
}

/// The pointer size of the target being compiled for, used to compute the
/// layout of Wasmtime's vmctx types.
pub fn ptr_size(&self) -> &Offsets::Ptr {
self.offsets.get_ptr_size()
}

/// Get the alias region for accesses into the GC heap.
pub fn gc_heap_region(&mut self, func: &mut ir::Function) -> ir::AliasRegion {
self.region(func, AliasRegionKey::GcHeap)
Expand Down
145 changes: 86 additions & 59 deletions crates/cranelift/src/compiler/component.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -13,11 +13,10 @@ use cranelift_codegen::ir::condcodes::IntCC;
use cranelift_codegen::ir::{self, InstBuilder, Value};
use cranelift_codegen::isa::{CallConv, TargetIsa};
use cranelift_frontend::FunctionBuilder;
use wasmtime_environ::GetPtrSize;
use wasmtime_environ::error::{Result, bail};
use wasmtime_environ::{
Abi, BuiltinFunctionIndex, CompiledFunctionBody, EntityRef, FuncKey, HostCall, PanicOnOom as _,
TrapSentinel, Tunables, WasmFuncType, WasmValType, component::*,
Abi, BuiltinFunctionIndex, CompiledFunctionBody, EntityRef, FuncKey, GetPtrSize, HostCall,
PanicOnOom as _, TrapSentinel, Tunables, WasmFuncType, WasmValType, component::*,
fact::PREPARE_CALL_FIXED_PARAMS,
};

Expand Down Expand Up @@ -1136,8 +1135,10 @@ impl<'a> TrampolineCompiler<'a> {
// old_may_block = load.i32 vmctx+$may_block_offset
// store 0, vmctx+$may_block_offset
//
// ;; call enter_sync_call, but only if the component instances
// ;; differ and concurrency is enabled
// ;; enter a sync call, but only if the component instances
// ;; differ and concurrency is enabled. This pushes an on-stack
// ;; `VMDeferredThread` and zeroes the live context slots; see
// ;; `enter_sync_call` below.
// ...
//
// ;; ============================================================
Expand All @@ -1149,16 +1150,17 @@ impl<'a> TrampolineCompiler<'a> {
// dtor = load.ptr vmctx+$offset
// func_addr = load.ptr dtor+$offset
// callee_vmctx = load.ptr dtor+$offset
// call_indirect func_addr, callee_vmctx, vmctx, rep
// ;; ============================================================
//
// ;; restore old value of may_block
// store old_may_block, vmctx+$may_block_offset
// call_indirect func_addr, callee_vmctx, vmctx, rep
//
// ;; if needed, call exit_sync_call
// ;; and restore the caller's slots afterwards
// store saved0, vmstore+$context_slot0
// ...
// ;; ============================================================
//
// ;; if needed, restore the old value of may_block
// ;; if needed, exit the sync call entered above and restore the
// ;; old value of may_block
// ...
// store old_may_block, vmctx+$may_block_offset
//
// jump return_block
Expand Down Expand Up @@ -1191,51 +1193,32 @@ impl<'a> TrampolineCompiler<'a> {
self.builder.switch_to_block(run_destructor_block);

// If this is a component-defined resource, the `may_leave` flag must be
// checked. Additionally, if concurrency is enabled, the `may_block`
// field must be updated and `enter_sync_call` called. Note though that
// all of that may be elided if the resource table resides in the same
// component instance that defined the resource as the component is
// calling itself.
let old_may_block = if let Some(def) = resource_def {
// checked. Additionally, if concurrency is enabled, the `may_block`
// field must be updated and a sync call entered.
let entered_sync_call = if has_destructor && let Some(def) = resource_def {
// Skip the may-leave check for self-owned resources.
if self.types[resource].unwrap_concrete_instance() != def.instance {
self.check_may_leave_instance(self.types[resource].unwrap_concrete_instance());
}

if self.compiler.tunables.concurrency_support {
// Stash the old value of `may_block` and then set it to false.
let old_may_block = self
.alias_regions
.vmcomponent()
.task_may_block()
.readonly()
.load(&mut self.builder.cursor(), vmctx);
let zero = self.builder.ins().iconst(ir::types::I32, i64::from(0));
self.alias_regions.vmcomponent().task_may_block().store(
&mut self.builder.cursor(),
vmctx,
zero,
);
if self.compiler.tunables.concurrency_support {
// Stash the old value of `may_block` and then set it to false.
let old_may_block = self
.alias_regions
.vmcomponent()
.task_may_block()
.readonly()
.load(&mut self.builder.cursor(), vmctx);
let zero = self.builder.ins().iconst(ir::types::I32, i64::from(0));
self.alias_regions.vmcomponent().task_may_block().store(
&mut self.builder.cursor(),
vmctx,
zero,
);

// Call `enter_sync_call`
//
// FIXME: Apply the optimizations described in #12311.
let host_args = vec![
vmctx,
self.builder
.ins()
.iconst(ir::types::I32, i64::from(instance.as_u32())),
self.builder.ins().iconst(ir::types::I32, i64::from(0)),
self.builder
.ins()
.iconst(ir::types::I32, i64::from(def.instance.as_u32())),
];
let call = self.call_libcall(vmctx, host::enter_sync_call, &host_args);
let result = self.builder.func.dfg.inst_results(call).get(0).copied();
self.raise_if_host_trapped(result.unwrap());

Some(old_may_block)
} else {
None
}
let slot = self.enter_sync_call_inline(instance, def.instance);

Some((old_may_block, slot))
} else {
None
}
Expand Down Expand Up @@ -1315,13 +1298,8 @@ impl<'a> TrampolineCompiler<'a> {
self.builder.seal_block(continuation);
}

if let Some(old_may_block) = old_may_block {
// Call `exit_sync_call`
//
// FIXME: Apply the optimizations described in #12311.
let call = self.call_libcall(vmctx, host::exit_sync_call, &[vmctx]);
let result = self.builder.func.dfg.inst_results(call).get(0).copied();
self.raise_if_host_trapped(result.unwrap());
if let Some((old_may_block, slot)) = entered_sync_call {
self.exit_sync_call_inline(vmctx, slot);

// Restore the old value of `may_block`
self.alias_regions.vmcomponent().task_may_block().store(
Expand All @@ -1339,6 +1317,55 @@ impl<'a> TrampolineCompiler<'a> {
self.abi_store_results(&[]);
}

/// Translates `enter-sync-call` around a resource destructor, deferring the
/// heavyweight task bookkeeping the `enter_sync_call` libcall would
/// otherwise do eagerly.
fn enter_sync_call_inline(
&mut self,
caller_instance: RuntimeComponentInstanceIndex,
callee_instance: RuntimeComponentInstanceIndex,
) -> ir::StackSlot {
let vmctx = self.caller_vmctx();
let caller_instance = self
.builder
.ins()
.iconst(ir::types::I32, i64::from(caller_instance.as_u32()));
let callee_async = self.builder.ins().iconst(ir::types::I32, 0);
let callee_instance = self
.builder
.ins()
.iconst(ir::types::I32, i64::from(callee_instance.as_u32()));
crate::component_sync_call::enter(
&mut self.builder,
&mut self.alias_regions,
vmctx,
crate::component_sync_call::EnterArgs {
caller_instance,
callee_async,
callee_instance,
},
)
}

/// Translates `exit-sync-call`, the counterpart to `enter_sync_call` above.
fn exit_sync_call_inline(&mut self, vmctx: ir::Value, slot: ir::StackSlot) {
// Note that the helper here wants a core wasm vmctx, not a component
// one like `vmctx` is in this function.
let caller_vmctx = self.caller_vmctx();
let slow = crate::component_sync_call::exit(
&mut self.builder,
&mut self.alias_regions,
caller_vmctx,
slot,
);

let call = self.call_libcall(vmctx, host::exit_sync_call, &[vmctx]);
let result = self.builder.func.dfg.inst_results(call).get(0).copied();
self.raise_if_host_trapped(result.unwrap());

slow.finish(&mut self.builder);
}

fn load_optional_memory(
&mut self,
vmctx: ir::Value,
Expand Down
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