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wasm linking: handle unreachable call_indirect

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The compiler crashed when we tried to call a function pointer for which
the type signature does not match any function body or function import
in the entire wasm executable, because there is no way to create a
reference to a function without it being in the function table or import
table. Solution is to make this instruction lower to unreachable.
This commit is contained in:
Andrew Kelley 2025-10-27 12:11:10 -07:00
parent 6ccb53bff1
commit 02119362d7
1 changed files with 14 additions and 2 deletions
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16
src/codegen/wasm/Emit.zig
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@ -188,8 +188,8 @@ pub fn lowerToCode(emit: *Emit) Error!void {
.fromInterned(fn_info.return_type),
target,
).?;
code.appendAssumeCapacity(@intFromEnum(std.wasm.Opcode.call_indirect));
if (is_obj) {
code.appendAssumeCapacity(@intFromEnum(std.wasm.Opcode.call_indirect));
try wasm.out_relocs.append(gpa, .{
.offset = @intCast(code.items.len),
.pointee = .{ .type_index = func_ty_index },
@ -198,7 +198,19 @@ pub fn lowerToCode(emit: *Emit) Error!void {
});
code.appendNTimesAssumeCapacity(0, 5);
} else {
const index: Wasm.Flush.FuncTypeIndex = .fromTypeIndex(func_ty_index, &wasm.flush_buffer);
const index: Wasm.Flush.FuncTypeIndex = @enumFromInt(wasm.flush_buffer.func_types.getIndex(func_ty_index) orelse {
// In this case we tried to call a function pointer for
// which the type signature does not match any function
// body or function import in the entire wasm executable.
//
// Since there is no way to create a reference to a
// function without it being in the function table or
// import table, this instruction is unreachable.
code.appendAssumeCapacity(@intFromEnum(std.wasm.Opcode.@"unreachable"));
inst += 1;
continue :loop tags[inst];
});
code.appendAssumeCapacity(@intFromEnum(std.wasm.Opcode.call_indirect));
writeUleb128(code, @intFromEnum(index));
}
writeUleb128(code, @as(u32, 0)); // table index