diff options
Diffstat (limited to 'src/upb_decoder_x64.asm')
| -rw-r--r-- | src/upb_decoder_x64.asm | 228 |
1 files changed, 0 insertions, 228 deletions
diff --git a/src/upb_decoder_x64.asm b/src/upb_decoder_x64.asm deleted file mode 100644 index c417644..0000000 --- a/src/upb_decoder_x64.asm +++ /dev/null @@ -1,228 +0,0 @@ -DEFAULT REL ; Default to RIP-relative addressing instead of absolute. - -extern _upb_decode_varint_fast64 - -SECTION .data - -; Our dispatch table; used to jump to the right handler, keyed on the field's -; type. -dispatch_table: - dq _upb_fastdecode.cant_fast_path ; field not in table (type == 0). (check_4). - dq _upb_fastdecode.fixed64 ; double - dq _upb_fastdecode.fixed32 ; float - dq _upb_fastdecode.varint ; int64 - dq _upb_fastdecode.varint ; uint64 - dq _upb_fastdecode.varint ; int32 - dq _upb_fastdecode.fixed64 ; fixed64 - dq _upb_fastdecode.fixed32 ; fixed32 - dq _upb_fastdecode.varint ; bool - dq _upb_fastdecode.string ; string - dq _upb_fastdecode.cant_fast_path ; group (check_6) - dq _upb_fastdecode.cant_fast_path ; message - dq _upb_fastdecode.string ; bytes - dq _upb_fastdecode.varint ; uint32 - dq _upb_fastdecode.varint ; enum - dq _upb_fastdecode.fixed32 ; sfixed32 - dq _upb_fastdecode.fixed64 ; sfixed64 - dq _upb_fastdecode.varint_sint32 ; sint32 - dq _upb_fastdecode.varint_sint64 ; sint64 - - GLOBAL _upb_decode_fast - -SECTION .text -; Register allocation. -%define BUF rbx ; const char *p, current buf position. -%define END rbp ; const char *end, where the buf ends (either submsg end or buf end) -%define STRING r12 ; unused -%define FVAL r13 ; upb_value fval, needs to be preserved across varint decoding call. -%define UNUSED r14 -%define CLOSURE r15 - -; Stack layout: *tableptr, uint32_t maxfield_times_8 -%define STACK_SPACE 24 ; this value + 8 must be a multiple of 16. -%define TABLE_SPILL [rsp] ; our lookup table, indexed by field number. -%define COMMITTED_BUF_SPILL [rsp+8] -%define MAXFIELD_TIMES_8_SPILL [rsp+16] - - -; Executing the fast path requires the following conditions: -; - check_1: there are >=12 bytes left (<=2 byte tag and <=10 byte varint). -; - check_2: the tag is <= 2 bytes. -; - check_3: the field number is <= the table size -; (ie. it must be an array lookup, not a hash lookup). -; - check_4: the field is known (found in the table). -; - check_5: the wire type we read is correct for the field number, -; ("packed" fields are not accepted, yet. this could be handled -; efficiently by doing an extra check on the "type check failed" -; path that goes into a tight loop if the encoding was packed). -; - check_6: the field is not a group or a message (or string, TODO) -; (this could be relaxed, but due to delegation it's a bit tricky). -; - check_7: if the value is a string, the entire string is available in -; the buffer, and our cached string object can be recycled, and -; our string object already references the source buffer, so -; absolutely no refcount twiddling is required. - - -%macro decode_and_dispatch_ 0 -align 16 -.decode_and_dispatch: - ; Load a few values we'll need in a sec. - mov r8, TABLE_SPILL - mov r9d, MAXFIELD_TIMES_8_SPILL - - mov rax, END - sub rax, BUF - cmp rax, 12 - jb _upb_fastdecode.cant_fast_path ; check_1 (<12 bytes left). - - ; Decode a 1 or 2-byte varint -> eax. - mov cl, byte [BUF] - lea rdi, [BUF+1] - movzx eax, cl - and eax, 0x7f - test cl, cl - jns .one_byte_tag ; Should be predictable if fields are in order. - movzx ecx, byte [BUF+1] - lea rdi, [BUF+2] - mov edx, ecx - and edx, 0x7f - shl edx, 7 - or eax, edx - test al, al - js _upb_fastdecode.cant_fast_path ; check_2 (tag was >2 bytes). -.one_byte_tag: - mov BUF, rdi - - ; Decode tag and dispatch. - mov ecx, eax - and eax, 0x3ff8 ; eax now contains field number * 8 - lea r11, [r8+rax*2] ; *2 is really *16, since rax is already *8. - and ecx, 0x7 ; ecx now contains wire type. - cmp eax, r9d - jae _upb_fastdecode.cant_fast_path ; check_3 (field number > table size) - mov FIELDDEF, [r11+8] ; Lookup fielddef (upb_itof_ent.f) - movzx rdx, BYTE [r11+1] ; Lookup field type. - mov rax, qword dispatch_table - jmp [rax+rdx*8] -%endmacro - -%macro decode_and_dispatch 0 - jmp .decode_and_dispatch -%endmacro - -%macro call_callback 0 - ; Value arg must already be in rdx when macro is called. - mov rdi, CLOSURE - mov rsi, FIELDDEF - mov rcx, 33 ; RAW; we could pass the correct type, or only do this in non-debug modes. - call CALLBACK - mov COMMITTED_BUF_SPILL, BUF - cmp eax, 0 - jne .done ; Caller requested BREAK or SKIPSUBMSG. -%endmacro - -%macro check_type 1 - cmp ecx, %1 - jne _upb_fastdecode.cant_fast_path ; check_5 (wire type check failed). -%endmacro - -; extern upb_flow_t upb_fastdecode(const char **p, const char *end, -; upb_value_handler_t value_cb, void *closure, -; void *table, int table_size); -align 16 -global _upb_fastdecode -_upb_fastdecode: - ; We use all callee-save regs. - push rbx - push rbp - push r12 - push r13 - push r14 - push r15 - sub rsp, STACK_SPACE - - ; Parse arguments into reg vals and stack. - mov BUF, rdi - mov COMMITTED_BUF_SPILL, rdi - mov END, rsi - mov CALLBACK, rdx - mov CLOSURE, rcx - mov TABLE_SPILL, r8 - shl r9, 3 - mov MAXFIELD_TIMES_8_SPILL, r9 - - decode_and_dispatch - -align 16 -.varint: - call _upb_decode_varint_fast64 ; BUF is already in rdi. - test rax, rax - jz _upb_fastdecode.cant_fast_path ; Varint was unterminated, slow path will handle error. - mov BUF, rax - call_callback ; rdx already holds value. - decode_and_dispatch_ - -align 16 -.fixed32: - mov edx, DWORD [BUF] ; Might be unaligned, but that's ok. - add BUF, 4 - call_callback - decode_and_dispatch - -align 16 -.fixed64: - mov rdx, QWORD [BUF] ; Might be unaligned, but that's ok. - add BUF, 8 - call_callback - decode_and_dispatch - -align 16 -.varint_sint32: - call _upb_decode_varint_fast64 ; BUF is already in rdi. - test rax, rax - jz _upb_fastdecode.cant_fast_path ; Varint was unterminated, slow path will handle error. - mov BUF, rax - - ; Perform 32-bit zig-zag decoding. - mov ecx, edx - shr edx, 1 - and ecx, 0x1 - neg ecx - xor edx, ecx - call_callback - decode_and_dispatch - -align 16 -.varint_sint64: - call _upb_decode_varint_fast64 ; BUF is already in rdi. - test rax, rax - jz _upb_fastdecode.cant_fast_path ; Varint was unterminated, slow path will handle error. - mov BUF, rax - - ; Perform 64-bit zig-zag decoding. - mov rcx, rdx - shr rdx, 1 - and ecx, 0x1 - neg rcx - xor rdx, rcx - call_callback - decode_and_dispatch - -align 16 -.string: - -.cant_fast_path: - mov rax, 0 ; UPB_CONTINUE -- continue as before. -.done: - ; If coming via done, preserve the user callback's return in rax. - - ; Return committed buf pointer as second parameter. - mov rdx, COMMITTED_BUF_SPILL - add rsp, STACK_SPACE - pop r15 - pop r14 - pop r13 - pop r12 - pop rbp - pop rbx - ret |