mirror/zig
1
0
Fork 0
mirror of https://github.com/ziglang/zig.git synced 2026-02-03 13:13:40 +00:00
Code Issues Packages Projects Releases Wiki Activity

wasm: implement @fence

Browse Source 
Uses the `atomic.fence` instruction for multi-thread-enabled builds
where the `atomics` feature is enabled for the wasm32 target.
In all other cases, this lowers to a nop.
This commit is contained in:
Luuk de Gram 2023-04-24 18:42:28 +02:00
parent b19c258f04
commit 0e3303ccd9
No known key found for this signature in database
GPG Key ID: A8CFE58E4DC7D664
2 changed files with 24 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
src/arch/wasm/CodeGen.zig
View File

@ -948,6 +948,12 @@ fn addAtomicMemArg(func: *CodeGen, tag: wasm.AtomicsOpcode, mem_arg: Mir.MemArg)
try func.addInst(.{ .tag = .atomics_prefix, .data = .{ .payload = extra_index } });
}
/// Helper function to emit atomic mir opcodes.
fn addAtomicTag(func: *CodeGen, tag: wasm.AtomicsOpcode) error{OutOfMemory}!void {
const extra_index = try func.addExtra(@as(struct { val: u32 }, .{ .val = wasm.atomicsOpcode(tag) }));
try func.addInst(.{ .tag = .atomics_prefix, .data = .{ .payload = extra_index } });
}
/// Appends entries to `mir_extra` based on the type of `extra`.
/// Returns the index into `mir_extra`
fn addExtra(func: *CodeGen, extra: anytype) error{OutOfMemory}!u32 {
@ -1964,7 +1970,6 @@ fn genInst(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {
.is_err_ptr,
.is_non_err_ptr,
.fence,
.atomic_store_unordered,
.atomic_store_monotonic,
.atomic_store_release,
@ -1985,6 +1990,7 @@ fn genInst(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {
.atomic_rmw => func.airAtomicRmw(inst),
.cmpxchg_weak => func.airCmpxchg(inst),
.cmpxchg_strong => func.airCmpxchg(inst),
.fence => func.airFence(inst),
.add_optimized,
.addwrap_optimized,
@ -6863,3 +6869,14 @@ fn airAtomicRmw(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {
return func.finishAir(inst, result, &.{ pl_op.operand, extra.operand });
}
}
fn airFence(func: *CodeGen, inst: Air.Inst.Index) InnerError!void {
// Only when the atomic feature is enabled, and we're not building
// for a single-threaded build, can we emit the `fence` instruction.
// In all other cases, we emit no instructions for a fence.
if (func.useAtomicFeature() and !func.bin_file.base.options.single_threaded) {
try func.addAtomicTag(.atomic_fence);
}
return func.finishAir(inst, .none, &.{});
}

6
src/arch/wasm/Emit.zig
View File

@ -595,6 +595,12 @@ fn emitAtomic(emit: *Emit, inst: Mir.Inst.Index) !void {
const mem_arg = emit.mir.extraData(Mir.MemArg, extra_index + 1).data;
try encodeMemArg(mem_arg, writer);
},
.atomic_fence => {
// TODO: When multi-memory proposal is accepted and implemented in the compiler,
// change this to (user-)specified index, rather than hardcode it to memory index 0.
const memory_index: u32 = 0;
try leb128.writeULEB128(writer, memory_index);
},
else => |tag| return emit.fail("TODO: Implement atomic instruction: {s}", .{@tagName(tag)}),
}
}