Repository navigation
error(x86_67_encoder): no encoding found for: none mov r64 m128 none none #24953
Description
Activity
Invalid AIR, source is never allowed to be a slice:
%8!= memcpy(%7!, <[]const u8, &.{}[0..0]>)Also length is never allowed to be comptime-known 0.
- marked x86 backend encoding failure concatenating slice #25485 as a duplicate of this issue
on Oct 11, 2025 Oh, looks like this is already fixed on master:
$ zig build-obj repro.zig $ zig build-obj repro.zig --verbose-air # Begin Function AIR: repro.repro: # Total AIR+Liveness bytes: 237B # AIR Instructions: 9 (81B) # AIR Extra Data: 9 (36B) # Liveness tomb_bits: 8B # Liveness Extra Data: 0 (0B) # Liveness special table: 0 (0B) %0!= arg(*[0]u8, 0) %1!= save_err_return_trace_index() %2!= dbg_stmt(2:5) %5!= alloc(*[0]u8) %6!= bitcast([*]u8, %5) %7!= bitcast(*const [0]u8, %5) %8!= ret_safe(@.void_value) # End Function AIR: repro.repro $
Builds correctly, and the bad AIR instruction is gone. I think I fixed this in my big type resolution diff---I do recall having to fix some AIR
memcpys.Closing as solved.
Zig Version
0.16.0-dev.1631+2aff85384
Steps to Reproduce and Observed Behavior
Minimal reproduction:
The size of
bytesdoesn't matter, it occurs for any pointer to a runtime-known array, specifically the pointee (i.e. even for a comptime-known pointer to a runtime-known array, for example, pointer to a global var).It appears related specifically to concatenation of a pointer to a runtime-known array with a slice, concatenating with a comptime-known array pointer does not reproduce this error - removing the
@asabove actually compiles, even for non-zero sizedbytes.*, strangely enough.Expected Behavior
Same behavior as concatenating an array pointer, which I would expect to be a compile error about being unable to concatenate using a pointer to a runtime-known value, but currently appears to construct a new pointer to a runtime-known value on the stack.