From c64199f4fce6c47323014b29623f78d0b3aad24f Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Sun, 26 Apr 2015 07:12:26 +0200 Subject: beam_asm: Speed up encoding of large numbers The misc_SUITE:integer_encoding/1 test case is annoyingly slow. Rewrite the encoding of integers in beam_asm to use the binary:encode_unsigned/1 BIF. Also tweak the test case itself. Scale the down the maximum size of the numbers being generated, but also add test of numbers around boundaries of power of two (which are the numbers most likely to expose bugs in the encoding). --- lib/compiler/src/beam_asm.erl | 44 +++++++++++++++++-------------------------- 1 file changed, 17 insertions(+), 27 deletions(-) (limited to 'lib/compiler/src') diff --git a/lib/compiler/src/beam_asm.erl b/lib/compiler/src/beam_asm.erl index 084686def7..73694b96ce 100644 --- a/lib/compiler/src/beam_asm.erl +++ b/lib/compiler/src/beam_asm.erl @@ -431,45 +431,35 @@ encode_alloc_list_1([], Dict, Acc) -> {iolist_to_binary(Acc),Dict}. encode(Tag, N) when N < 0 -> - encode1(Tag, negative_to_bytes(N, [])); + encode1(Tag, negative_to_bytes(N)); encode(Tag, N) when N < 16 -> (N bsl 4) bor Tag; encode(Tag, N) when N < 16#800 -> [((N bsr 3) band 2#11100000) bor Tag bor 2#00001000, N band 16#ff]; encode(Tag, N) -> - encode1(Tag, to_bytes(N, [])). + encode1(Tag, to_bytes(N)). encode1(Tag, Bytes) -> - case length(Bytes) of + case iolist_size(Bytes) of Num when 2 =< Num, Num =< 8 -> [((Num-2) bsl 5) bor 2#00011000 bor Tag| Bytes]; Num when 8 < Num -> [2#11111000 bor Tag, encode(?tag_u, Num-9)| Bytes] end. - -to_bytes(N0, Acc) -> - Bits = 3*128, - case N0 bsr Bits of - 0 -> - to_bytes_1(N0, Acc); - N -> - to_bytes(N, binary_to_list(<>) ++ Acc) - end. - -to_bytes_1(0, [B|_]=Done) when B < 128 -> Done; -to_bytes_1(N, Acc) -> to_bytes(N bsr 8, [N band 16#ff|Acc]). - -negative_to_bytes(N0, Acc) -> - Bits = 3*128, - case N0 bsr Bits of - -1 -> - negative_to_bytes_1(N0, Acc); - N -> - negative_to_bytes_1(N, binary_to_list(<>) ++ Acc) +to_bytes(N) -> + Bin = binary:encode_unsigned(N), + case Bin of + <<0:1,_/bits>> -> Bin; + <<1:1,_/bits>> -> [0,Bin] end. -negative_to_bytes_1(-1, [B1,_B2|_]=Done) when B1 > 127 -> - Done; -negative_to_bytes_1(N, Acc) -> - negative_to_bytes_1(N bsr 8, [N band 16#ff|Acc]). +negative_to_bytes(N) when N >= -16#8000 -> + <>; +negative_to_bytes(N) -> + Bytes = byte_size(binary:encode_unsigned(-N)), + Bin = <>, + case Bin of + <<0:1,_/bits>> -> [16#ff,Bin]; + <<1:1,_/bits>> -> Bin + end. -- cgit v1.2.3