unlzma: speedup, by Pascal Bellard (pascal.bellard AT ads-lu.com)
authorDenis Vlasenko <vda.linux@googlemail.com>
Sat, 25 Apr 2009 12:19:35 +0000 (12:19 -0000)
committerDenis Vlasenko <vda.linux@googlemail.com>
Sat, 25 Apr 2009 12:19:35 +0000 (12:19 -0000)
LZMA_FAST off: 10% faster and:
function                                             old     new   delta
rc_is_bit_1                                            -      92     +92
rc_do_normalize                                       45      81     +36
rc_update_bit_1                                       25       -     -25
rc_update_bit_0                                       30       -     -30
rc_is_bit_0_helper                                    38       -     -38
rc_get_bit                                            60      17     -43
rc_read                                               48       -     -48
unpack_lzma_stream                                  1768    1517    -251
------------------------------------------------------------------------------
(add/remove: 1/4 grow/shrink: 1/2 up/down: 128/-435)         Total: -307 bytes

LZMA_FAST on: 14% faster and:
unpack_lzma_stream                                  2301    2737    +436
rc_get_bit                                           106       -    -106

archival/Config.in
archival/libunarchive/decompress_unlzma.c

index 64b44c218c90f311614f8bb02de2089a29a35ea9..e0d43c0ee5eda4925a3a3bb90429ba45169d1d1c 100644 (file)
@@ -283,8 +283,8 @@ config FEATURE_LZMA_FAST
        default n
        depends on UNLZMA
        help
-         This option reduces decompression time by about 33% at the cost of
-         a 2K bigger binary.
+         This option reduces decompression time by about 25% at the cost of
+         a 1K bigger binary.
 
 config UNZIP
        bool "unzip"
index 33e5cd65d40c58d8d9029000789b5bed444d806e..68085d68c8a42d008cc0b146d7d8217c193f2371 100644 (file)
@@ -8,14 +8,15 @@
  *
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */
-
 #include "libbb.h"
 #include "unarchive.h"
 
 #if ENABLE_FEATURE_LZMA_FAST
 #  define speed_inline ALWAYS_INLINE
+#  define size_inline
 #else
 #  define speed_inline
+#  define size_inline ALWAYS_INLINE
 #endif
 
 
@@ -44,8 +45,8 @@ typedef struct {
 #define RC_MODEL_TOTAL_BITS 11
 
 
-/* Called twice: once at startup and once in rc_normalize() */
-static void rc_read(rc_t *rc)
+/* Called twice: once at startup (LZMA_FAST only) and once in rc_normalize() */
+static size_inline void rc_read(rc_t *rc)
 {
        int buffer_size = safe_read(rc->fd, RC_BUFFER, RC_BUFFER_SIZE);
        if (buffer_size <= 0)
@@ -54,8 +55,17 @@ static void rc_read(rc_t *rc)
        rc->buffer_end = RC_BUFFER + buffer_size;
 }
 
+/* Called twice, but one callsite is in speed_inline'd rc_is_bit_1() */
+static void rc_do_normalize(rc_t *rc)
+{
+       if (rc->ptr >= rc->buffer_end)
+               rc_read(rc);
+       rc->range <<= 8;
+       rc->code = (rc->code << 8) | *rc->ptr++;
+}
+
 /* Called once */
-static rc_t* rc_init(int fd) /*, int buffer_size) */
+static ALWAYS_INLINE rc_t* rc_init(int fd) /*, int buffer_size) */
 {
        int i;
        rc_t *rc;
@@ -63,17 +73,18 @@ static rc_t* rc_init(int fd) /*, int buffer_size) */
        rc = xmalloc(sizeof(*rc) + RC_BUFFER_SIZE);
 
        rc->fd = fd;
-       /* rc->buffer_size = buffer_size; */
-       rc->buffer_end = RC_BUFFER + RC_BUFFER_SIZE;
        rc->ptr = rc->buffer_end;
 
-       rc->code = 0;
-       rc->range = 0xFFFFFFFF;
        for (i = 0; i < 5; i++) {
+#if ENABLE_FEATURE_LZMA_FAST
                if (rc->ptr >= rc->buffer_end)
                        rc_read(rc);
                rc->code = (rc->code << 8) | *rc->ptr++;
+#else
+               rc_do_normalize(rc);
+#endif
        }
+       rc->range = 0xFFFFFFFF;
        return rc;
 }
 
@@ -83,14 +94,6 @@ static ALWAYS_INLINE void rc_free(rc_t *rc)
        free(rc);
 }
 
-/* Called twice, but one callsite is in speed_inline'd rc_is_bit_0_helper() */
-static void rc_do_normalize(rc_t *rc)
-{
-       if (rc->ptr >= rc->buffer_end)
-               rc_read(rc);
-       rc->range <<= 8;
-       rc->code = (rc->code << 8) | *rc->ptr++;
-}
 static ALWAYS_INLINE void rc_normalize(rc_t *rc)
 {
        if (rc->range < (1 << RC_TOP_BITS)) {
@@ -98,49 +101,28 @@ static ALWAYS_INLINE void rc_normalize(rc_t *rc)
        }
 }
 
-/* rc_is_bit_0 is called 9 times */
-/* Why rc_is_bit_0_helper exists?
- * Because we want to always expose (rc->code < rc->bound) to optimizer.
- * Thus rc_is_bit_0 is always inlined, and rc_is_bit_0_helper is inlined
- * only if we compile for speed.
- */
-static speed_inline uint32_t rc_is_bit_0_helper(rc_t *rc, uint16_t *p)
+/* rc_is_bit_1 is called 9 times */
+static speed_inline int rc_is_bit_1(rc_t *rc, uint16_t *p)
 {
        rc_normalize(rc);
        rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS);
-       return rc->bound;
-}
-static ALWAYS_INLINE int rc_is_bit_0(rc_t *rc, uint16_t *p)
-{
-       uint32_t t = rc_is_bit_0_helper(rc, p);
-       return rc->code < t;
-}
-
-/* Called ~10 times, but very small, thus inlined */
-static speed_inline void rc_update_bit_0(rc_t *rc, uint16_t *p)
-{
-       rc->range = rc->bound;
-       *p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
-}
-static speed_inline void rc_update_bit_1(rc_t *rc, uint16_t *p)
-{
+       if (rc->code < rc->bound) {
+               rc->range = rc->bound;
+               *p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
+               return 0;
+       }
        rc->range -= rc->bound;
        rc->code -= rc->bound;
        *p -= *p >> RC_MOVE_BITS;
+       return 1;
 }
 
 /* Called 4 times in unlzma loop */
-static int rc_get_bit(rc_t *rc, uint16_t *p, int *symbol)
+static speed_inline int rc_get_bit(rc_t *rc, uint16_t *p, int *symbol)
 {
-       if (rc_is_bit_0(rc, p)) {
-               rc_update_bit_0(rc, p);
-               *symbol *= 2;
-               return 0;
-       } else {
-               rc_update_bit_1(rc, p);
-               *symbol = *symbol * 2 + 1;
-               return 1;
-       }
+       int ret = rc_is_bit_1(rc, p);
+       *symbol = *symbol * 2 + ret;
+       return ret;
 }
 
 /* Called once */
@@ -266,13 +248,13 @@ unpack_lzma_stream(int src_fd, int dst_fd)
        header.dst_size = SWAP_LE64(header.dst_size);
 
        if (header.dict_size == 0)
-               header.dict_size = 1;
+               header.dict_size++;
 
        buffer = xmalloc(MIN(header.dst_size, header.dict_size));
 
        num_probs = LZMA_BASE_SIZE + (LZMA_LIT_SIZE << (lc + lp));
        p = xmalloc(num_probs * sizeof(*p));
-       num_probs = LZMA_LITERAL + (LZMA_LIT_SIZE << (lc + lp));
+       num_probs += LZMA_LITERAL - LZMA_BASE_SIZE;
        for (i = 0; i < num_probs; i++)
                p[i] = (1 << RC_MODEL_TOTAL_BITS) >> 1;
 
@@ -282,9 +264,8 @@ unpack_lzma_stream(int src_fd, int dst_fd)
                int pos_state = (buffer_pos + global_pos) & pos_state_mask;
 
                prob = p + LZMA_IS_MATCH + (state << LZMA_NUM_POS_BITS_MAX) + pos_state;
-               if (rc_is_bit_0(rc, prob)) {
+               if (!rc_is_bit_1(rc, prob)) {
                        mi = 1;
-                       rc_update_bit_0(rc, prob);
                        prob = (p + LZMA_LITERAL
                                + (LZMA_LIT_SIZE * ((((buffer_pos + global_pos) & literal_pos_mask) << lc)
                                                    + (previous_byte >> (8 - lc))
@@ -340,27 +321,21 @@ unpack_lzma_stream(int src_fd, int dst_fd)
                        int offset;
                        uint16_t *prob_len;
 
-                       rc_update_bit_1(rc, prob);
                        prob = p + LZMA_IS_REP + state;
-                       if (rc_is_bit_0(rc, prob)) {
-                               rc_update_bit_0(rc, prob);
+                       if (!rc_is_bit_1(rc, prob)) {
                                rep3 = rep2;
                                rep2 = rep1;
                                rep1 = rep0;
                                state = state < LZMA_NUM_LIT_STATES ? 0 : 3;
                                prob = p + LZMA_LEN_CODER;
                        } else {
-                               rc_update_bit_1(rc, prob);
-                               prob = p + LZMA_IS_REP_G0 + state;
-                               if (rc_is_bit_0(rc, prob)) {
-                                       rc_update_bit_0(rc, prob);
+                               prob += LZMA_IS_REP_G0 - LZMA_IS_REP;
+                               if (!rc_is_bit_1(rc, prob)) {
                                        prob = (p + LZMA_IS_REP_0_LONG
                                                + (state << LZMA_NUM_POS_BITS_MAX)
                                                + pos_state
                                        );
-                                       if (rc_is_bit_0(rc, prob)) {
-                                               rc_update_bit_0(rc, prob);
-
+                                       if (!rc_is_bit_1(rc, prob)) {
                                                state = state < LZMA_NUM_LIT_STATES ? 9 : 11;
 #if ENABLE_FEATURE_LZMA_FAST
                                                pos = buffer_pos - rep0;
@@ -372,25 +347,16 @@ unpack_lzma_stream(int src_fd, int dst_fd)
                                                len = 1;
                                                goto string;
 #endif
-                                       } else {
-                                               rc_update_bit_1(rc, prob);
                                        }
                                } else {
                                        uint32_t distance;
 
-                                       rc_update_bit_1(rc, prob);
-                                       prob = p + LZMA_IS_REP_G1 + state;
-                                       if (rc_is_bit_0(rc, prob)) {
-                                               rc_update_bit_0(rc, prob);
-                                               distance = rep1;
-                                       } else {
-                                               rc_update_bit_1(rc, prob);
-                                               prob = p + LZMA_IS_REP_G2 + state;
-                                               if (rc_is_bit_0(rc, prob)) {
-                                                       rc_update_bit_0(rc, prob);
-                                                       distance = rep2;
-                                               } else {
-                                                       rc_update_bit_1(rc, prob);
+                                       prob += LZMA_IS_REP_G1 - LZMA_IS_REP_G0;
+                                       distance = rep1;
+                                       if (rc_is_bit_1(rc, prob)) {
+                                               prob += LZMA_IS_REP_G2 - LZMA_IS_REP_G1;
+                                               distance = rep2;
+                                               if (rc_is_bit_1(rc, prob)) {
                                                        distance = rep3;
                                                        rep3 = rep2;
                                                }
@@ -404,24 +370,20 @@ unpack_lzma_stream(int src_fd, int dst_fd)
                        }
 
                        prob_len = prob + LZMA_LEN_CHOICE;
-                       if (rc_is_bit_0(rc, prob_len)) {
-                               rc_update_bit_0(rc, prob_len);
-                               prob_len = (prob + LZMA_LEN_LOW
-                                           + (pos_state << LZMA_LEN_NUM_LOW_BITS));
+                       if (!rc_is_bit_1(rc, prob_len)) {
+                               prob_len += LZMA_LEN_LOW - LZMA_LEN_CHOICE
+                                           + (pos_state << LZMA_LEN_NUM_LOW_BITS);
                                offset = 0;
                                num_bits = LZMA_LEN_NUM_LOW_BITS;
                        } else {
-                               rc_update_bit_1(rc, prob_len);
-                               prob_len = prob + LZMA_LEN_CHOICE_2;
-                               if (rc_is_bit_0(rc, prob_len)) {
-                                       rc_update_bit_0(rc, prob_len);
-                                       prob_len = (prob + LZMA_LEN_MID
-                                                   + (pos_state << LZMA_LEN_NUM_MID_BITS));
+                               prob_len += LZMA_LEN_CHOICE_2 - LZMA_LEN_CHOICE;
+                               if (!rc_is_bit_1(rc, prob_len)) {
+                                       prob_len += LZMA_LEN_MID - LZMA_LEN_CHOICE_2
+                                                   + (pos_state << LZMA_LEN_NUM_MID_BITS);
                                        offset = 1 << LZMA_LEN_NUM_LOW_BITS;
                                        num_bits = LZMA_LEN_NUM_MID_BITS;
                                } else {
-                                       rc_update_bit_1(rc, prob_len);
-                                       prob_len = prob + LZMA_LEN_HIGH;
+                                       prob_len += LZMA_LEN_HIGH - LZMA_LEN_CHOICE_2;
                                        offset = ((1 << LZMA_LEN_NUM_LOW_BITS)
                                                  + (1 << LZMA_LEN_NUM_MID_BITS));
                                        num_bits = LZMA_LEN_NUM_HIGH_BITS;
@@ -438,19 +400,20 @@ unpack_lzma_stream(int src_fd, int dst_fd)
                                       ((len < LZMA_NUM_LEN_TO_POS_STATES ? len :
                                         LZMA_NUM_LEN_TO_POS_STATES - 1)
                                         << LZMA_NUM_POS_SLOT_BITS);
-                               rc_bit_tree_decode(rc, prob, LZMA_NUM_POS_SLOT_BITS,
-                                                                  &pos_slot);
+                               rc_bit_tree_decode(rc, prob,
+                                       LZMA_NUM_POS_SLOT_BITS, &pos_slot);
+                               rep0 = pos_slot;
                                if (pos_slot >= LZMA_START_POS_MODEL_INDEX) {
                                        num_bits = (pos_slot >> 1) - 1;
                                        rep0 = 2 | (pos_slot & 1);
+                                       prob = p + LZMA_ALIGN;
                                        if (pos_slot < LZMA_END_POS_MODEL_INDEX) {
                                                rep0 <<= num_bits;
-                                               prob = p + LZMA_SPEC_POS + rep0 - pos_slot - 1;
+                                               prob += LZMA_SPEC_POS - LZMA_ALIGN - 1 + rep0 - pos_slot;
                                        } else {
                                                num_bits -= LZMA_NUM_ALIGN_BITS;
                                                while (num_bits--)
                                                        rep0 = (rep0 << 1) | rc_direct_bit(rc);
-                                               prob = p + LZMA_ALIGN;
                                                rep0 <<= LZMA_NUM_ALIGN_BITS;
                                                num_bits = LZMA_NUM_ALIGN_BITS;
                                        }
@@ -461,8 +424,7 @@ unpack_lzma_stream(int src_fd, int dst_fd)
                                                        rep0 |= i;
                                                i <<= 1;
                                        }
-                               } else
-                                       rep0 = pos_slot;
+                               }
                                if (++rep0 == 0)
                                        break;
                        }