From: Eric Biggers Date: Tue, 27 May 2014 14:28:59 +0000 (-0500) Subject: lzx-decompress.c: Add SSE2 version of undo_call_insn_preprocessing() X-Git-Tag: v1.7.0~79 X-Git-Url: https://wimlib.net/git/?p=wimlib;a=commitdiff_plain;h=869ca1f4cc4654501d52f8c3e660c056904ccabf lzx-decompress.c: Add SSE2 version of undo_call_insn_preprocessing() --- diff --git a/src/lzx-decompress.c b/src/lzx-decompress.c index 05093266..d3ba46af 100644 --- a/src/lzx-decompress.c +++ b/src/lzx-decompress.c @@ -7,7 +7,7 @@ */ /* - * Copyright (C) 2012, 2013 Eric Biggers + * Copyright (C) 2012, 2013, 2014 Eric Biggers * * This file is part of wimlib, a library for working with WIM files. * @@ -115,6 +115,10 @@ #include +#ifdef __SSE2__ +# include +#endif + /* Huffman decoding tables and maps from symbols to code lengths. */ struct lzx_tables { @@ -711,20 +715,19 @@ lzx_decode_match(unsigned main_element, int block_type, } static void -undo_call_insn_translation(u32 *call_insn_target, s32 input_pos, - s32 file_size) +undo_call_insn_translation(u32 *call_insn_target, s32 input_pos) { s32 abs_offset; s32 rel_offset; abs_offset = le32_to_cpu(*call_insn_target); - if (abs_offset >= -input_pos && abs_offset < file_size) { + if (abs_offset >= -input_pos && abs_offset < LZX_WIM_MAGIC_FILESIZE) { if (abs_offset >= 0) { /* "good translation" */ rel_offset = abs_offset - input_pos; } else { /* "compensating translation" */ - rel_offset = abs_offset + file_size; + rel_offset = abs_offset + LZX_WIM_MAGIC_FILESIZE; } *call_insn_target = cpu_to_le32(rel_offset); } @@ -753,15 +756,99 @@ undo_call_insn_translation(u32 *call_insn_target, s32 input_pos, * as it is used in calculating the translated jump targets. But in WIM files, * this file size is always the same (LZX_WIM_MAGIC_FILESIZE == 12000000).*/ static void -undo_call_insn_preprocessing(u8 *uncompressed_data, s32 uncompressed_size) +undo_call_insn_preprocessing(u8 *uncompressed_data, size_t uncompressed_size) { - for (s32 i = 0; i < uncompressed_size - 10; i++) { - if (uncompressed_data[i] == 0xe8) { - undo_call_insn_translation((u32*)&uncompressed_data[i + 1], - i, - LZX_WIM_MAGIC_FILESIZE); - i += 4; - } +#ifdef __SSE2__ + + /* SSE2 vectorized implementation for x86_64. This speeds up LZX + * decompression by about 5-8% overall. (Usually --- the performance + * actually regresses slightly in the degenerate case that the data + * consists entirely of 0xe8 bytes.) */ + __m128i *p128 = (__m128i *)uncompressed_data; + u32 valid_mask = 0xFFFFFFFF; + + if (uncompressed_size >= 32 && + ((uintptr_t)uncompressed_data % 16 == 0)) + { + __m128i * const end128 = p128 + uncompressed_size / 16 - 1; + + /* Create a vector of all 0xe8 bytes */ + const __m128i e8_bytes = _mm_set1_epi8(0xe8); + + /* Iterate through the 16-byte vectors in the input. */ + do { + /* Compare the current 16-byte vector with the vector of + * all 0xe8 bytes. This produces 0xff where the byte is + * 0xe8 and 0x00 where it is not. */ + __m128i cmpresult = _mm_cmpeq_epi8(*p128, e8_bytes); + + /* Map the comparison results into a single 16-bit + * number. It will contain a 1 bit when the + * corresponding byte in the current 16-byte vector is + * an e8 byte. Note: the low-order bit corresponds to + * the first (lowest address) byte. */ + u32 e8_mask = _mm_movemask_epi8(cmpresult); + + if (!e8_mask) { + /* If e8_mask is 0, then none of these 16 bytes + * have value 0xe8. No e8 translation is + * needed, and there is no restriction that + * carries over to the next 16 bytes. */ + valid_mask = 0xFFFFFFFF; + } else { + /* At least one byte has value 0xe8. + * + * The AND with valid_mask accounts for the fact + * that we can't start an e8 translation that + * overlaps the previous one. */ + while ((e8_mask &= valid_mask)) { + + /* Count the number of trailing zeroes + * in e8_mask. This will produce the + * index of the byte, within the 16, at + * which the next e8 translation should + * be done. */ + u32 bit = __builtin_ctz(e8_mask); + + /* Do the e8 translation. */ + u8 *p8 = (u8 *)p128 + bit; + undo_call_insn_translation((s32 *)(p8 + 1), + p8 - uncompressed_data); + + /* Don't start an e8 translation in the + * next 4 bytes. */ + valid_mask &= ~((u32)0x1F << bit); + } + /* Moving on to the next vector. Shift and set + * valid_mask accordingly. */ + valid_mask >>= 16; + valid_mask |= 0xFFFF0000; + } + } while (++p128 < end128); + } + + u8 *p8 = (u8 *)p128; + while (!(valid_mask & 1)) { + p8++; + valid_mask >>= 1; + } +#else /* __SSE2__ */ + u8 *p8 = uncompressed_data; +#endif /* !__SSE2__ */ + + if (uncompressed_size > 10) { + /* Finish any bytes that weren't processed by the vectorized + * implementation. */ + u8 *p8_end = uncompressed_data + uncompressed_size - 10; + do { + if (*p8 == 0xe8) { + undo_call_insn_translation((s32 *)(p8 + 1), + p8 - uncompressed_data); + p8 += 5; + } else { + p8++; + } + } while (p8 < p8_end); } } diff --git a/src/resource.c b/src/resource.c index f7684b10..300aec8f 100644 --- a/src/resource.c +++ b/src/resource.c @@ -138,6 +138,7 @@ read_compressed_wim_resource(const struct wim_resource_spec * const rspec, int errno_save; u64 *chunk_offsets = NULL; + u8 *_ubuf = NULL; u8 *ubuf = NULL; void *cbuf = NULL; bool chunk_offsets_malloced = false; @@ -368,13 +369,14 @@ read_compressed_wim_resource(const struct wim_resource_spec * const rspec, /* Allocate buffer for holding the uncompressed data of each chunk. */ if (chunk_size <= STACK_MAX) { - ubuf = alloca(chunk_size); + _ubuf = alloca(chunk_size + 15); } else { - ubuf = MALLOC(chunk_size); - if (ubuf == NULL) + _ubuf = MALLOC(chunk_size + 15); + if (_ubuf == NULL) goto oom; ubuf_malloced = true; } + ubuf = (u8 *)(((uintptr_t)_ubuf + 15) & ~15); /* Allocate a temporary buffer for reading compressed chunks, each of * which can be at most @chunk_size - 1 bytes. This excludes compressed @@ -548,7 +550,7 @@ out_free_memory: if (chunk_offsets_malloced) FREE(chunk_offsets); if (ubuf_malloced) - FREE(ubuf); + FREE(_ubuf); if (cbuf_malloced) FREE(cbuf); errno = errno_save;