unlzma: fixed speedup/shrink by Pascal Bellard (pascal.bellard AT ads-lu.com)

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 108 insertions, 146 deletions

diff --git a/archival/Config.in b/archival/Config.in
index 71b9538..cae7f20 100644
--- a/archival/Config.in
+++ b/archival/Config.in
@@ -298,8 +298,8 @@ 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"
diff --git a/archival/libunarchive/decompress_unlzma.c b/archival/libunarchive/decompress_unlzma.c
index 33e5cd6..4478cd2 100644
--- a/archival/libunarchive/decompress_unlzma.c
+++ b/archival/libunarchive/decompress_unlzma.c
@@ -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
 
 
@@ -44,36 +45,48 @@ 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);
+//TODO: return -1 instead
+//This will make unlzma delete broken unpacked file on unpack errors
 	if (buffer_size <= 0)
 		bb_error_msg_and_die("unexpected EOF");
 	rc->ptr = RC_BUFFER;
 	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;
 
-	rc = xmalloc(sizeof(*rc) + RC_BUFFER_SIZE);
+	rc = xzalloc(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->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 +96,6 @@ 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 +103,28 @@ 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 */
@@ -236,14 +220,11 @@ unpack_lzma_stream(int src_fd, int dst_fd)
 	int lc, pb, lp;
 	uint32_t pos_state_mask;
 	uint32_t literal_pos_mask;
-	uint32_t pos;
 	uint16_t *p;
-	uint16_t *prob;
-	uint16_t *prob_lit;
 	int num_bits;
 	int num_probs;
 	rc_t *rc;
-	int i, mi;
+	int i;
 	uint8_t *buffer;
 	uint8_t previous_byte = 0;
 	size_t buffer_pos = 0, global_pos = 0;
@@ -251,14 +232,17 @@ unpack_lzma_stream(int src_fd, int dst_fd)
 	int state = 0;
 	uint32_t rep0 = 1, rep1 = 1, rep2 = 1, rep3 = 1;
 
-	xread(src_fd, &header, sizeof(header));
+	if (full_read(src_fd, &header, sizeof(header)) != sizeof(header)
+	 || header.pos >= (9 * 5 * 5)
+	) {
+		bb_error_msg("bad lzma header");
+		return -1;
+	}
 
-	if (header.pos >= (9 * 5 * 5))
-		bb_error_msg_and_die("bad header");
-	mi = header.pos / 9;
+	i = header.pos / 9;
 	lc = header.pos % 9;
-	pb = mi / 5;
-	lp = mi % 5;
+	pb = i / 5;
+	lp = i % 5;
 	pos_state_mask = (1 << pb) - 1;
 	literal_pos_mask = (1 << lp) - 1;
 
@@ -266,13 +250,13 @@ 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;
 
@@ -280,11 +264,13 @@ unpack_lzma_stream(int src_fd, int dst_fd)
 
 	while (global_pos + buffer_pos < header.dst_size) {
 		int pos_state = (buffer_pos + global_pos) & pos_state_mask;
+		uint16_t *prob = p + LZMA_IS_MATCH + (state << LZMA_NUM_POS_BITS_MAX) + pos_state;
+
+		if (!rc_is_bit_1(rc, prob)) {
+			static const char next_state[LZMA_NUM_STATES] =
+				{ 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 4, 5 };
+			int mi = 1;
 
-		prob = p + LZMA_IS_MATCH + (state << LZMA_NUM_POS_BITS_MAX) + pos_state;
-		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))
@@ -294,8 +280,8 @@ unpack_lzma_stream(int src_fd, int dst_fd)
 
 			if (state >= LZMA_NUM_LIT_STATES) {
 				int match_byte;
+				uint32_t pos = buffer_pos - rep0;
 
-				pos = buffer_pos - rep0;
 				while (pos >= header.dict_size)
 					pos += header.dict_size;
 				match_byte = buffer[pos];
@@ -304,22 +290,16 @@ unpack_lzma_stream(int src_fd, int dst_fd)
 
 					match_byte <<= 1;
 					bit = match_byte & 0x100;
-					prob_lit = prob + 0x100 + bit + mi;
-					bit ^= (rc_get_bit(rc, prob_lit, &mi) << 8); /* 0x100 or 0 */
+					bit ^= (rc_get_bit(rc, prob + 0x100 + bit + mi, &mi) << 8); /* 0x100 or 0 */
 					if (bit)
 						break;
 				} while (mi < 0x100);
 			}
 			while (mi < 0x100) {
-				prob_lit = prob + mi;
-				rc_get_bit(rc, prob_lit, &mi);
+				rc_get_bit(rc, prob + mi, &mi);
 			}
 
-			state -= 3;
-			if (state < 4-3)
-				state = 0;
-			if (state >= 10-3)
-				state -= 6-3;
+			state = next_state[state];
 
 			previous_byte = (uint8_t) mi;
 #if ENABLE_FEATURE_LZMA_FAST
@@ -338,59 +318,46 @@ unpack_lzma_stream(int src_fd, int dst_fd)
 #endif
 		} else {
 			int offset;
-			uint16_t *prob_len;
+			uint16_t *prob2;
+#define prob_len prob2
 
-			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);
+			prob2 = p + LZMA_IS_REP + state;
+			if (!rc_is_bit_1(rc, prob2)) {
 				rep3 = rep2;
 				rep2 = rep1;
 				rep1 = rep0;
 				state = state < LZMA_NUM_LIT_STATES ? 0 : 3;
-				prob = p + LZMA_LEN_CODER;
+				prob2 = 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 = (p + LZMA_IS_REP_0_LONG
+				prob2 += LZMA_IS_REP_G0 - LZMA_IS_REP;
+				if (!rc_is_bit_1(rc, prob2)) {
+					prob2 = (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);
-
-						state = state < LZMA_NUM_LIT_STATES ? 9 : 11;
+					if (!rc_is_bit_1(rc, prob2)) {
 #if ENABLE_FEATURE_LZMA_FAST
-						pos = buffer_pos - rep0;
+						uint32_t pos = buffer_pos - rep0;
+						state = state < LZMA_NUM_LIT_STATES ? 9 : 11;
 						while (pos >= header.dict_size)
 							pos += header.dict_size;
 						previous_byte = buffer[pos];
 						goto one_byte1;
 #else
+						state = state < LZMA_NUM_LIT_STATES ? 9 : 11;
 						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);
+					prob2 += LZMA_IS_REP_G1 - LZMA_IS_REP_G0;
+					distance = rep1;
+					if (rc_is_bit_1(rc, prob2)) {
+						prob2 += LZMA_IS_REP_G2 - LZMA_IS_REP_G1;
+						distance = rep2;
+						if (rc_is_bit_1(rc, prob2)) {
 							distance = rep3;
 							rep3 = rep2;
 						}
@@ -400,31 +367,27 @@ unpack_lzma_stream(int src_fd, int dst_fd)
 					rep0 = distance;
 				}
 				state = state < LZMA_NUM_LIT_STATES ? 8 : 11;
-				prob = p + LZMA_REP_LEN_CODER;
+				prob2 = p + LZMA_REP_LEN_CODER;
 			}
 
-			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));
+			prob_len = prob2 + LZMA_LEN_CHOICE;
+			num_bits = 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;
+					num_bits += LZMA_LEN_NUM_MID_BITS - LZMA_LEN_NUM_LOW_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;
+					num_bits += LZMA_LEN_NUM_HIGH_BITS - LZMA_LEN_NUM_LOW_BITS;
 				}
 			}
 			rc_bit_tree_decode(rc, prob_len, num_bits, &len);
@@ -432,37 +395,36 @@ unpack_lzma_stream(int src_fd, int dst_fd)
 
 			if (state < 4) {
 				int pos_slot;
+				uint16_t *prob3;
 
 				state += LZMA_NUM_LIT_STATES;
-				prob = p + LZMA_POS_SLOT +
+				prob3 = p + LZMA_POS_SLOT +
 				       ((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, prob3,
+					LZMA_NUM_POS_SLOT_BITS, &pos_slot);
+				rep0 = pos_slot;
 				if (pos_slot >= LZMA_START_POS_MODEL_INDEX) {
-					num_bits = (pos_slot >> 1) - 1;
+					int i2, mi2, num_bits2 = (pos_slot >> 1) - 1;
 					rep0 = 2 | (pos_slot & 1);
 					if (pos_slot < LZMA_END_POS_MODEL_INDEX) {
-						rep0 <<= num_bits;
-						prob = p + LZMA_SPEC_POS + rep0 - pos_slot - 1;
+						rep0 <<= num_bits2;
+						prob3 = p + LZMA_SPEC_POS + rep0 - pos_slot - 1;
 					} else {
-						num_bits -= LZMA_NUM_ALIGN_BITS;
-						while (num_bits--)
+						for (; num_bits2 != LZMA_NUM_ALIGN_BITS; num_bits2--)
 							rep0 = (rep0 << 1) | rc_direct_bit(rc);
-						prob = p + LZMA_ALIGN;
 						rep0 <<= LZMA_NUM_ALIGN_BITS;
-						num_bits = LZMA_NUM_ALIGN_BITS;
+						prob3 = p + LZMA_ALIGN;
 					}
-					i = 1;
-					mi = 1;
-					while (num_bits--) {
-						if (rc_get_bit(rc, prob + mi, &mi))
-							rep0 |= i;
-						i <<= 1;
+					i2 = 1;
+					mi2 = 1;
+					while (num_bits2--) {
+						if (rc_get_bit(rc, prob3 + mi2, &mi2))
+							rep0 |= i2;
+						i2 <<= 1;
 					}
-				} else
-					rep0 = pos_slot;
+				}
 				if (++rep0 == 0)
 					break;
 			}
@@ -470,7 +432,7 @@ unpack_lzma_stream(int src_fd, int dst_fd)
 			len += LZMA_MATCH_MIN_LEN;
  IF_NOT_FEATURE_LZMA_FAST(string:)
 			do {
-				pos = buffer_pos - rep0;
+				uint32_t pos = buffer_pos - rep0;
 				while (pos >= header.dict_size)
 					pos += header.dict_size;
 				previous_byte = buffer[pos];