Revert "unlzma: speedup, by Pascal Bellard (pascal.bellard AT ads-lu.com)"
authorDenys Vlasenko <vda.linux@googlemail.com>
Sun, 6 Sep 2009 13:06:25 +0000 (15:06 +0200)
committerDenys Vlasenko <vda.linux@googlemail.com>
Sun, 6 Sep 2009 13:06:25 +0000 (15:06 +0200)
https://bugs.busybox.net/show_bug.cgi?id=599

This reverts commit 9ac3dc764a78b51fe8fdcd1b4682850de098733b.

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

index cae7f20bbe2c07a7294338f8094bd3fbaa0fc550..71b95381998d9054c44feb2542786966f815a782 100644 (file)
@@ -298,8 +298,8 @@ config FEATURE_LZMA_FAST
        default n
        depends on UNLZMA
        help
-         This option reduces decompression time by about 25% at the cost of
-         a 1K bigger binary.
+         This option reduces decompression time by about 33% at the cost of
+         a 2K bigger binary.
 
 config UNZIP
        bool "unzip"
index 68085d68c8a42d008cc0b146d7d8217c193f2371..33e5cd65d40c58d8d9029000789b5bed444d806e 100644 (file)
@@ -8,15 +8,14 @@
  *
  * 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
 
 
@@ -45,8 +44,8 @@ typedef struct {
 #define RC_MODEL_TOTAL_BITS 11
 
 
-/* Called twice: once at startup (LZMA_FAST only) and once in rc_normalize() */
-static size_inline void rc_read(rc_t *rc)
+/* Called twice: once at startup and once in rc_normalize() */
+static void rc_read(rc_t *rc)
 {
        int buffer_size = safe_read(rc->fd, RC_BUFFER, RC_BUFFER_SIZE);
        if (buffer_size <= 0)
@@ -55,17 +54,8 @@ static size_inline 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 ALWAYS_INLINE rc_t* rc_init(int fd) /*, int buffer_size) */
+static rc_t* rc_init(int fd) /*, int buffer_size) */
 {
        int i;
        rc_t *rc;
@@ -73,18 +63,17 @@ static ALWAYS_INLINE 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;
 }
 
@@ -94,6 +83,14 @@ 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)) {
@@ -101,28 +98,49 @@ static ALWAYS_INLINE void rc_normalize(rc_t *rc)
        }
 }
 
-/* rc_is_bit_1 is called 9 times */
-static speed_inline int rc_is_bit_1(rc_t *rc, uint16_t *p)
+/* 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_normalize(rc);
        rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS);
-       if (rc->code < rc->bound) {
-               rc->range = rc->bound;
-               *p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
-               return 0;
-       }
+       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)
+{
        rc->range -= rc->bound;
        rc->code -= rc->bound;
        *p -= *p >> RC_MOVE_BITS;
-       return 1;
 }
 
 /* Called 4 times in unlzma loop */
-static speed_inline int rc_get_bit(rc_t *rc, uint16_t *p, int *symbol)
+static int rc_get_bit(rc_t *rc, uint16_t *p, int *symbol)
 {
-       int ret = rc_is_bit_1(rc, p);
-       *symbol = *symbol * 2 + ret;
-       return ret;
+       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;
+       }
 }
 
 /* Called once */
@@ -248,13 +266,13 @@ 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++;
+               header.dict_size = 1;
 
        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_BASE_SIZE;
+       num_probs = LZMA_LITERAL + (LZMA_LIT_SIZE << (lc + lp));
        for (i = 0; i < num_probs; i++)
                p[i] = (1 << RC_MODEL_TOTAL_BITS) >> 1;
 
@@ -264,8 +282,9 @@ 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_1(rc, prob)) {
+               if (rc_is_bit_0(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))
@@ -321,21 +340,27 @@ 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_1(rc, prob)) {
+                       if (rc_is_bit_0(rc, prob)) {
+                               rc_update_bit_0(rc, prob);
                                rep3 = rep2;
                                rep2 = rep1;
                                rep1 = rep0;
                                state = state < LZMA_NUM_LIT_STATES ? 0 : 3;
                                prob = p + LZMA_LEN_CODER;
                        } else {
-                               prob += LZMA_IS_REP_G0 - LZMA_IS_REP;
-                               if (!rc_is_bit_1(rc, prob)) {
+                               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 = (p + LZMA_IS_REP_0_LONG
                                                + (state << LZMA_NUM_POS_BITS_MAX)
                                                + pos_state
                                        );
-                                       if (!rc_is_bit_1(rc, prob)) {
+                                       if (rc_is_bit_0(rc, prob)) {
+                                               rc_update_bit_0(rc, prob);
+
                                                state = state < LZMA_NUM_LIT_STATES ? 9 : 11;
 #if ENABLE_FEATURE_LZMA_FAST
                                                pos = buffer_pos - rep0;
@@ -347,16 +372,25 @@ 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;
 
-                                       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)) {
+                                       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);
                                                        distance = rep3;
                                                        rep3 = rep2;
                                                }
@@ -370,20 +404,24 @@ unpack_lzma_stream(int src_fd, int dst_fd)
                        }
 
                        prob_len = prob + LZMA_LEN_CHOICE;
-                       if (!rc_is_bit_1(rc, prob_len)) {
-                               prob_len += LZMA_LEN_LOW - LZMA_LEN_CHOICE
-                                           + (pos_state << LZMA_LEN_NUM_LOW_BITS);
+                       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));
                                offset = 0;
                                num_bits = LZMA_LEN_NUM_LOW_BITS;
                        } else {
-                               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);
+                               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));
                                        offset = 1 << LZMA_LEN_NUM_LOW_BITS;
                                        num_bits = LZMA_LEN_NUM_MID_BITS;
                                } else {
-                                       prob_len += LZMA_LEN_HIGH - LZMA_LEN_CHOICE_2;
+                                       rc_update_bit_1(rc, prob_len);
+                                       prob_len = prob + LZMA_LEN_HIGH;
                                        offset = ((1 << LZMA_LEN_NUM_LOW_BITS)
                                                  + (1 << LZMA_LEN_NUM_MID_BITS));
                                        num_bits = LZMA_LEN_NUM_HIGH_BITS;
@@ -400,20 +438,19 @@ 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);
-                               rep0 = pos_slot;
+                               rc_bit_tree_decode(rc, prob, LZMA_NUM_POS_SLOT_BITS,
+                                                                  &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 += LZMA_SPEC_POS - LZMA_ALIGN - 1 + rep0 - pos_slot;
+                                               prob = p + LZMA_SPEC_POS + rep0 - pos_slot - 1;
                                        } 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;
                                        }
@@ -424,7 +461,8 @@ unpack_lzma_stream(int src_fd, int dst_fd)
                                                        rep0 |= i;
                                                i <<= 1;
                                        }
-                               }
+                               } else
+                                       rep0 = pos_slot;
                                if (++rep0 == 0)
                                        break;
                        }