Update contrib/libs/lzma to 5.6.0

de6c124a343d1b577cd3e4a152607415cfd3de0e

1 files changed, 809 insertions, 29 deletions

diff --git a/contrib/libs/lzma/liblzma/rangecoder/range_decoder.h b/contrib/libs/lzma/liblzma/rangecoder/range_decoder.h
index e0b051fac2d..b6422247f3c 100644
--- a/contrib/libs/lzma/liblzma/rangecoder/range_decoder.h
+++ b/contrib/libs/lzma/liblzma/rangecoder/range_decoder.h
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: 0BSD
+
 ///////////////////////////////////////////////////////////////////////////////
 //
 /// \file       range_decoder.h
@@ -6,9 +8,6 @@
 //  Authors:    Igor Pavlov
 //              Lasse Collin
 //
-//  This file has been put into the public domain.
-//  You can do whatever you want with this file.
-//
 ///////////////////////////////////////////////////////////////////////////////
 
 #ifndef LZMA_RANGE_DECODER_H
@@ -17,6 +16,54 @@
 #include "range_common.h"
 
 
+// Choose the range decoder variants to use using a bitmask.
+// If no bits are set, only the basic version is used.
+// If more than one version is selected for the same feature,
+// the last one on the list below is used.
+//
+// Bitwise-or of the following enable branchless C versions:
+//   0x01   normal bittrees
+//   0x02   fixed-sized reverse bittrees
+//   0x04   variable-sized reverse bittrees (not faster)
+//   0x08   matched literal (not faster)
+//
+// GCC & Clang compatible x86-64 inline assembly:
+//   0x010   normal bittrees
+//   0x020   fixed-sized reverse bittrees
+//   0x040   variable-sized reverse bittrees
+//   0x080   matched literal
+//   0x100   direct bits
+//
+// The default can be overridden at build time by defining
+// LZMA_RANGE_DECODER_CONFIG to the desired mask.
+//
+// 2024-02-22: Feedback from benchmarks:
+//   - Brancless C (0x003) can be better than basic on x86-64 but often it's
+//     slightly worse on other archs. Since asm is much better on x86-64,
+//     branchless C is not used at all.
+//   - With x86-64 asm, there are slight differences between GCC and Clang
+//     and different processors. Overall 0x1F0 seems to be the best choice.
+#ifndef LZMA_RANGE_DECODER_CONFIG
+#	if defined(__x86_64__) && !defined(__ILP32__) \
+			&& (defined(__GNUC__) || defined(__clang__))
+#		define LZMA_RANGE_DECODER_CONFIG 0x1F0
+#	else
+#		define LZMA_RANGE_DECODER_CONFIG 0
+#	endif
+#endif
+
+
+// Negative RC_BIT_MODEL_TOTAL but the lowest RC_MOVE_BITS are flipped.
+// This is useful for updating probability variables in branchless decoding:
+//
+//     uint32_t decoded_bit = ...;
+//     probability tmp = RC_BIT_MODEL_OFFSET;
+//     tmp &= decoded_bit - 1;
+//     prob -= (prob + tmp) >> RC_MOVE_BITS;
+#define RC_BIT_MODEL_OFFSET \
+	((UINT32_C(1) << RC_MOVE_BITS) - 1 - RC_BIT_MODEL_TOTAL)
+
+
 typedef struct {
 	uint32_t range;
 	uint32_t code;
@@ -50,18 +97,28 @@ rc_read_init(lzma_range_decoder *rc, const uint8_t *restrict in,
 
 /// Makes local copies of range decoder and *in_pos variables. Doing this
 /// improves speed significantly. The range decoder macros expect also
-/// variables `in' and `in_size' to be defined.
-#define rc_to_local(range_decoder, in_pos) \
+/// variables 'in' and 'in_size' to be defined.
+#define rc_to_local(range_decoder, in_pos, fast_mode_in_required) \
 	lzma_range_decoder rc = range_decoder; \
-	size_t rc_in_pos = (in_pos); \
+	const uint8_t *rc_in_ptr = in + (in_pos); \
+	const uint8_t *rc_in_end = in + in_size; \
+	const uint8_t *rc_in_fast_end \
+			= (rc_in_end - rc_in_ptr) <= (fast_mode_in_required) \
+			? rc_in_ptr \
+			: rc_in_end - (fast_mode_in_required); \
+	(void)rc_in_fast_end; /* Silence a warning with HAVE_SMALL. */ \
 	uint32_t rc_bound
 
 
+/// Evaluates to true if there is enough input remaining to use fast mode.
+#define rc_is_fast_allowed() (rc_in_ptr < rc_in_fast_end)
+
+
 /// Stores the local copes back to the range decoder structure.
 #define rc_from_local(range_decoder, in_pos) \
 do { \
 	range_decoder = rc; \
-	in_pos = rc_in_pos; \
+	in_pos = (size_t)(rc_in_ptr - in); \
 } while (0)
 
 
@@ -81,18 +138,30 @@ do { \
 	((range_decoder).code == 0)
 
 
-/// Read the next input byte if needed. If more input is needed but there is
+// Read the next input byte if needed.
+#define rc_normalize() \
+do { \
+	if (rc.range < RC_TOP_VALUE) { \
+		rc.range <<= RC_SHIFT_BITS; \
+		rc.code = (rc.code << RC_SHIFT_BITS) | *rc_in_ptr++; \
+	} \
+} while (0)
+
+
+/// If more input is needed but there is
 /// no more input available, "goto out" is used to jump out of the main
-/// decoder loop.
-#define rc_normalize(seq) \
+/// decoder loop. The "_safe" macros are used in the Resumable decoder
+/// mode in order to save the sequence to continue decoding from that
+/// point later.
+#define rc_normalize_safe(seq) \
 do { \
 	if (rc.range < RC_TOP_VALUE) { \
-		if (unlikely(rc_in_pos == in_size)) { \
+		if (rc_in_ptr == rc_in_end) { \
 			coder->sequence = seq; \
 			goto out; \
 		} \
 		rc.range <<= RC_SHIFT_BITS; \
-		rc.code = (rc.code << RC_SHIFT_BITS) | in[rc_in_pos++]; \
+		rc.code = (rc.code << RC_SHIFT_BITS) | *rc_in_ptr++; \
 	} \
 } while (0)
 
@@ -100,7 +169,7 @@ do { \
 /// Start decoding a bit. This must be used together with rc_update_0()
 /// and rc_update_1():
 ///
-///     rc_if_0(prob, seq) {
+///     rc_if_0(prob) {
 ///         rc_update_0(prob);
 ///         // Do something
 ///     } else {
@@ -108,18 +177,28 @@ do { \
 ///         // Do something else
 ///     }
 ///
-#define rc_if_0(prob, seq) \
-	rc_normalize(seq); \
+#define rc_if_0(prob) \
+	rc_normalize(); \
+	rc_bound = (rc.range >> RC_BIT_MODEL_TOTAL_BITS) * (prob); \
+	if (rc.code < rc_bound)
+
+
+#define rc_if_0_safe(prob, seq) \
+	rc_normalize_safe(seq); \
 	rc_bound = (rc.range >> RC_BIT_MODEL_TOTAL_BITS) * (prob); \
 	if (rc.code < rc_bound)
 
 
 /// Update the range decoder state and the used probability variable to
 /// match a decoded bit of 0.
+///
+/// The x86-64 assembly uses the commented method but it seems that,
+/// at least on x86-64, the first version is slightly faster as C code.
 #define rc_update_0(prob) \
 do { \
 	rc.range = rc_bound; \
 	prob += (RC_BIT_MODEL_TOTAL - (prob)) >> RC_MOVE_BITS; \
+	/* prob -= ((prob) + RC_BIT_MODEL_OFFSET) >> RC_MOVE_BITS; */ \
 } while (0)
 
 
@@ -137,9 +216,21 @@ do { \
 /// This macro is used as the last step in bittree reverse decoders since
 /// those don't use "symbol" for anything else than indexing the probability
 /// arrays.
-#define rc_bit_last(prob, action0, action1, seq) \
+#define rc_bit_last(prob, action0, action1) \
+do { \
+	rc_if_0(prob) { \
+		rc_update_0(prob); \
+		action0; \
+	} else { \
+		rc_update_1(prob); \
+		action1; \
+	} \
+} while (0)
+
+
+#define rc_bit_last_safe(prob, action0, action1, seq) \
 do { \
-	rc_if_0(prob, seq) { \
+	rc_if_0_safe(prob, seq) { \
 		rc_update_0(prob); \
 		action0; \
 	} else { \
@@ -151,35 +242,724 @@ do { \
 
 /// Decodes one bit, updates "symbol", and runs action0 or action1 depending
 /// on the decoded bit.
-#define rc_bit(prob, action0, action1, seq) \
+#define rc_bit(prob, action0, action1) \
 	rc_bit_last(prob, \
 		symbol <<= 1; action0, \
+		symbol = (symbol << 1) + 1; action1);
+
+
+#define rc_bit_safe(prob, action0, action1, seq) \
+	rc_bit_last_safe(prob, \
+		symbol <<= 1; action0, \
 		symbol = (symbol << 1) + 1; action1, \
 		seq);
 
+// Unroll fixed-sized bittree decoding.
+//
+// A compile-time constant in final_add can be used to get rid of the high bit
+// from symbol that is used for the array indexing (1U << bittree_bits).
+// final_add may also be used to add offset to the result (LZMA length
+// decoder does that).
+//
+// The reason to have final_add here is that in the asm code the addition
+// can be done for free: in x86-64 there is SBB instruction with -1 as
+// the immediate value, and final_add is combined with that value.
+#define rc_bittree_bit(prob) \
+	rc_bit(prob, , )
+
+#define rc_bittree3(probs, final_add) \
+do { \
+	symbol = 1; \
+	rc_bittree_bit(probs[symbol]); \
+	rc_bittree_bit(probs[symbol]); \
+	rc_bittree_bit(probs[symbol]); \
+	symbol += (uint32_t)(final_add); \
+} while (0)
 
-/// Like rc_bit() but add "case seq:" as a prefix. This makes the unrolled
-/// loops more readable because the code isn't littered with "case"
-/// statements. On the other hand this also makes it less readable, since
-/// spotting the places where the decoder loop may be restarted is less
-/// obvious.
-#define rc_bit_case(prob, action0, action1, seq) \
-	case seq: rc_bit(prob, action0, action1, seq)
+#define rc_bittree6(probs, final_add) \
+do { \
+	symbol = 1; \
+	rc_bittree_bit(probs[symbol]); \
+	rc_bittree_bit(probs[symbol]); \
+	rc_bittree_bit(probs[symbol]); \
+	rc_bittree_bit(probs[symbol]); \
+	rc_bittree_bit(probs[symbol]); \
+	rc_bittree_bit(probs[symbol]); \
+	symbol += (uint32_t)(final_add); \
+} while (0)
+
+#define rc_bittree8(probs, final_add) \
+do { \
+	symbol = 1; \
+	rc_bittree_bit(probs[symbol]); \
+	rc_bittree_bit(probs[symbol]); \
+	rc_bittree_bit(probs[symbol]); \
+	rc_bittree_bit(probs[symbol]); \
+	rc_bittree_bit(probs[symbol]); \
+	rc_bittree_bit(probs[symbol]); \
+	rc_bittree_bit(probs[symbol]); \
+	rc_bittree_bit(probs[symbol]); \
+	symbol += (uint32_t)(final_add); \
+} while (0)
+
+
+// Fixed-sized reverse bittree
+#define rc_bittree_rev4(probs) \
+do { \
+	symbol = 0; \
+	rc_bit_last(probs[symbol + 1], , symbol += 1); \
+	rc_bit_last(probs[symbol + 2], , symbol += 2); \
+	rc_bit_last(probs[symbol + 4], , symbol += 4); \
+	rc_bit_last(probs[symbol + 8], , symbol += 8); \
+} while (0)
+
+
+// Decode one bit from variable-sized reverse bittree. The loop is done
+// in the code that uses this macro. This could be changed if the assembly
+// version benefited from having the loop done in assembly but it didn't
+// seem so in early 2024.
+//
+// Also, if the loop was done here, the loop counter would likely be local
+// to the macro so that it wouldn't modify yet another input variable.
+// If a _safe version of a macro with a loop was done then a modifiable
+// input variable couldn't be avoided though.
+#define rc_bit_add_if_1(probs, dest, value_to_add_if_1) \
+	rc_bit(probs[symbol], \
+		, \
+		dest += value_to_add_if_1);
+
+
+// Matched literal
+#define decode_with_match_bit \
+		t_match_byte <<= 1; \
+		t_match_bit = t_match_byte & t_offset; \
+		t_subcoder_index = t_offset + t_match_bit + symbol; \
+		rc_bit(probs[t_subcoder_index], \
+				t_offset &= ~t_match_bit, \
+				t_offset &= t_match_bit)
+
+#define rc_matched_literal(probs_base_var, match_byte) \
+do { \
+	uint32_t t_match_byte = (match_byte); \
+	uint32_t t_match_bit; \
+	uint32_t t_subcoder_index; \
+	uint32_t t_offset = 0x100; \
+	symbol = 1; \
+	decode_with_match_bit; \
+	decode_with_match_bit; \
+	decode_with_match_bit; \
+	decode_with_match_bit; \
+	decode_with_match_bit; \
+	decode_with_match_bit; \
+	decode_with_match_bit; \
+	decode_with_match_bit; \
+} while (0)
 
 
 /// Decode a bit without using a probability.
-#define rc_direct(dest, seq) \
+//
+// NOTE: GCC 13 and Clang/LLVM 16 can, at least on x86-64, optimize the bound
+// calculation to use an arithmetic right shift so there's no need to provide
+// the alternative code which, according to C99/C11/C23 6.3.1.3-p3 isn't
+// perfectly portable: rc_bound = (uint32_t)((int32_t)rc.code >> 31);
+#define rc_direct(dest, count_var) \
 do { \
-	rc_normalize(seq); \
+	dest = (dest << 1) + 1; \
+	rc_normalize(); \
+	rc.range >>= 1; \
+	rc.code -= rc.range; \
+	rc_bound = UINT32_C(0) - (rc.code >> 31); \
+	dest += rc_bound; \
+	rc.code += rc.range & rc_bound; \
+} while (--count_var > 0)
+
+
+
+#define rc_direct_safe(dest, count_var, seq) \
+do { \
+	rc_normalize_safe(seq); \
 	rc.range >>= 1; \
 	rc.code -= rc.range; \
 	rc_bound = UINT32_C(0) - (rc.code >> 31); \
 	rc.code += rc.range & rc_bound; \
 	dest = (dest << 1) + (rc_bound + 1); \
+} while (--count_var > 0)
+
+
+//////////////////
+// Branchless C //
+//////////////////
+
+/// Decode a bit using a branchless method. This reduces the number of
+/// mispredicted branches and thus can improve speed.
+#define rc_c_bit(prob, action_bit, action_neg) \
+do { \
+	probability *p = &(prob); \
+	rc_normalize(); \
+	rc_bound = (rc.range >> RC_BIT_MODEL_TOTAL_BITS) * *p; \
+	uint32_t rc_mask = rc.code >= rc_bound; /* rc_mask = decoded bit */ \
+	action_bit; /* action when rc_mask is 0 or 1 */ \
+	/* rc_mask becomes 0 if bit is 0 and 0xFFFFFFFF if bit is 1: */ \
+	rc_mask = 0U - rc_mask; \
+	rc.range &= rc_mask; /* If bit 0: set rc.range = 0 */ \
+	rc_bound ^= rc_mask; \
+	rc_bound -= rc_mask; /* If bit 1: rc_bound = 0U - rc_bound */ \
+	rc.range += rc_bound; \
+	rc_bound &= rc_mask; \
+	rc.code += rc_bound; \
+	action_neg; /* action when rc_mask is 0 or 0xFFFFFFFF */ \
+	rc_mask = ~rc_mask; /* If bit 0: all bits are set in rc_mask */ \
+	rc_mask &= RC_BIT_MODEL_OFFSET; \
+	*p -= (*p + rc_mask) >> RC_MOVE_BITS; \
 } while (0)
 
 
-// NOTE: No macros are provided for bittree decoding. It seems to be simpler
-// to just write them open in the code.
+// Testing on x86-64 give an impression that only the normal bittrees and
+// the fixed-sized reverse bittrees are worth the branchless C code.
+// It should be tested on other archs for which there isn't assembly code
+// in this file.
+
+// Using addition in "(symbol << 1) + rc_mask" allows use of x86 LEA
+// or RISC-V SH1ADD instructions. Compilers might infer it from
+// "(symbol << 1) | rc_mask" too if they see that mask is 0 or 1 but
+// the use of addition doesn't require such analysis from compilers.
+#if LZMA_RANGE_DECODER_CONFIG & 0x01
+#undef rc_bittree_bit
+#define rc_bittree_bit(prob) \
+	rc_c_bit(prob, \
+		symbol = (symbol << 1) + rc_mask, \
+		)
+#endif // LZMA_RANGE_DECODER_CONFIG & 0x01
+
+#if LZMA_RANGE_DECODER_CONFIG & 0x02
+#undef rc_bittree_rev4
+#define rc_bittree_rev4(probs) \
+do { \
+	symbol = 0; \
+	rc_c_bit(probs[symbol + 1], symbol += rc_mask, ); \
+	rc_c_bit(probs[symbol + 2], symbol += rc_mask << 1, ); \
+	rc_c_bit(probs[symbol + 4], symbol += rc_mask << 2, ); \
+	rc_c_bit(probs[symbol + 8], symbol += rc_mask << 3, ); \
+} while (0)
+#endif // LZMA_RANGE_DECODER_CONFIG & 0x02
+
+#if LZMA_RANGE_DECODER_CONFIG & 0x04
+#undef rc_bit_add_if_1
+#define rc_bit_add_if_1(probs, dest, value_to_add_if_1) \
+	rc_c_bit(probs[symbol], \
+		symbol = (symbol << 1) + rc_mask, \
+		dest += (value_to_add_if_1) & rc_mask)
+#endif // LZMA_RANGE_DECODER_CONFIG & 0x04
+
+
+#if LZMA_RANGE_DECODER_CONFIG & 0x08
+#undef decode_with_match_bit
+#define decode_with_match_bit \
+		t_match_byte <<= 1; \
+		t_match_bit = t_match_byte & t_offset; \
+		t_subcoder_index = t_offset + t_match_bit + symbol; \
+		rc_c_bit(probs[t_subcoder_index], \
+			symbol = (symbol << 1) + rc_mask, \
+			t_offset &= ~t_match_bit ^ rc_mask)
+#endif // LZMA_RANGE_DECODER_CONFIG & 0x08
+
+
+////////////
+// x86-64 //
+////////////
+
+#if LZMA_RANGE_DECODER_CONFIG & 0x1F0
+
+// rc_asm_y and rc_asm_n are used as arguments to macros to control which
+// strings to include or omit.
+#define rc_asm_y(str) str
+#define rc_asm_n(str)
+
+// There are a few possible variations for normalization.
+// This is the smallest variant which is also used by LZMA SDK.
+//
+//   - This has partial register write (the MOV from (%[in_ptr])).
+//
+//   - INC saves one byte in code size over ADD. False dependency on
+//     partial flags from INC shouldn't become a problem on any processor
+//     because the instructions after normalization don't read the flags
+//     until SUB which sets all flags.
+//
+#define rc_asm_normalize \
+	"cmp	%[top_value], %[range]\n\t" \
+	"jae	1f\n\t" \
+	"shl	%[shift_bits], %[code]\n\t" \
+	"mov	(%[in_ptr]), %b[code]\n\t" \
+	"shl	%[shift_bits], %[range]\n\t" \
+	"inc	%[in_ptr]\n" \
+	"1:\n"
+
+// rc_asm_calc(prob) is roughly equivalent to the C version of rc_if_0(prob)...
+//
+//     rc_bound = (rc.range >> RC_BIT_MODEL_TOTAL_BITS) * (prob);
+//     if (rc.code < rc_bound)
+//
+// ...but the bound is stored in "range":
+//
+//     t0 = range;
+//     range = (range >> RC_BIT_MODEL_TOTAL_BITS) * (prob);
+//     t0 -= range;
+//     t1 = code;
+//     code -= range;
+//
+// The carry flag (CF) from the last subtraction holds the negation of
+// the decoded bit (if CF==0 then the decoded bit is 1).
+// The values in t0 and t1 are needed for rc_update_0(prob) and
+// rc_update_1(prob). If the bit is 0, rc_update_0(prob)...
+//
+//     rc.range = rc_bound;
+//
+// ...has already been done but the "code -= range" has to be reverted using
+// the old value stored in t1. (Also, prob needs to be updated.)
+//
+// If the bit is 1, rc_update_1(prob)...
+//
+//     rc.range -= rc_bound;
+//     rc.code -= rc_bound;
+//
+// ...is already done for "code" but the value for "range" needs to be taken
+// from t0. (Also, prob needs to be updated here as well.)
+//
+// The assignments from t0 and t1 can be done in a branchless manner with CMOV
+// after the instructions from this macro. The CF from SUB tells which moves
+// are needed.
+#define rc_asm_calc(prob) \
+		"mov	%[range], %[t0]\n\t" \
+		"shr	%[bit_model_total_bits], %[range]\n\t" \
+		"imul	%[" prob "], %[range]\n\t" \
+		"sub	%[range], %[t0]\n\t" \
+		"mov	%[code], %[t1]\n\t" \
+		"sub	%[range], %[code]\n\t"
+
+// Also, prob needs to be updated: The update math depends on the decoded bit.
+// It can be expressed in a few slightly different ways but this is fairly
+// convenient here:
+//
+//     prob -= (prob + (bit ? 0 : RC_BIT_MODEL_OFFSET)) >> RC_MOVE_BITS;
+//
+// To do it in branchless way when the negation of the decoded bit is in CF,
+// both "prob" and "prob + RC_BIT_MODEL_OFFSET" are needed. Then the desired
+// value can be picked with CMOV. The addition can be done using LEA without
+// affecting CF.
+//
+// (This prob update method is a tiny bit different from LZMA SDK 23.01.
+// In the LZMA SDK a single register is reserved solely for a constant to
+// be used with CMOV when updating prob. That is fine since there are enough
+// free registers to do so. The method used here uses one fewer register,
+// which is valuable with inline assembly.)
+//
+// * * *
+//
+// In bittree decoding, each (unrolled) loop iteration decodes one bit
+// and needs one prob variable. To make it faster, the prob variable of
+// the iteration N+1 is loaded during iteration N. There are two possible
+// prob variables to choose from for N+1. Both are loaded from memory and
+// the correct one is chosen with CMOV using the same CF as is used for
+// other things described above.
+//
+// This preloading/prefetching requires an extra register. To avoid
+// useless moves from "preloaded prob register" to "current prob register",
+// the macros swap between the two registers for odd and even iterations.
+//
+// * * *
+//
+// Finally, the decoded bit has to be stored in "symbol". Since the negation
+// of the bit is in CF, this can be done with SBB: symbol -= CF - 1. That is,
+// if the decoded bit is 0 (CF==1) the operation is a no-op "symbol -= 0"
+// and when bit is 1 (CF==0) the operation is "symbol -= 0 - 1" which is
+// the same as "symbol += 1".
+//
+// The instructions for all things are intertwined for a few reasons:
+//   - freeing temporary registers for new use
+//   - not modifying CF too early
+//   - instruction scheduling
+//
+// The first and last iterations can cheat a little. For example,
+// on the first iteration "symbol" is known to start from 1 so it
+// doesn't need to be read; it can even be immediately initialized
+// to 2 to prepare for the second iteration of the loop.
+//
+// * * *
+//
+// a = number of the current prob variable (0 or 1)
+// b = number of the next prob variable (1 or 0)
+// *_only = rc_asm_y or _n to include or exclude code marked with them
+#define rc_asm_bittree(a, b, first_only, middle_only, last_only) \
+	first_only( \
+		"movzw	2(%[probs_base]), %[prob" #a "]\n\t" \
+		"mov	$2, %[symbol]\n\t" \
+		"movzw	4(%[probs_base]), %[prob" #b "]\n\t" \
+	) \
+	middle_only( \
+		/* Note the scaling of 4 instead of 2: */ \
+		"movzw	(%[probs_base], %q[symbol], 4), %[prob" #b "]\n\t" \
+	) \
+	last_only( \
+		"add	%[symbol], %[symbol]\n\t" \
+	) \
+		\
+		rc_asm_normalize \
+		rc_asm_calc("prob" #a) \
+		\
+		"cmovae	%[t0], %[range]\n\t" \
+		\
+	first_only( \
+		"movzw	6(%[probs_base]), %[t0]\n\t" \
+		"cmovae	%[t0], %[prob" #b "]\n\t" \
+	) \
+	middle_only( \
+		"movzw	2(%[probs_base], %q[symbol], 4), %[t0]\n\t" \
+		"lea	(%q[symbol], %q[symbol]), %[symbol]\n\t" \
+		"cmovae	%[t0], %[prob" #b "]\n\t" \
+	) \
+		\
+		"lea	%c[bit_model_offset](%q[prob" #a "]), %[t0]\n\t" \
+		"cmovb	%[t1], %[code]\n\t" \
+		"mov	%[symbol], %[t1]\n\t" \
+		"cmovae	%[prob" #a "], %[t0]\n\t" \
+		\
+	first_only( \
+		"sbb	$-1, %[symbol]\n\t" \
+	) \
+	middle_only( \
+		"sbb	$-1, %[symbol]\n\t" \
+	) \
+	last_only( \
+		"sbb	%[last_sbb], %[symbol]\n\t" \
+	) \
+		\
+		"shr	%[move_bits], %[t0]\n\t" \
+		"sub	%[t0], %[prob" #a "]\n\t" \
+		/* Scaling of 1 instead of 2 because symbol <<= 1. */ \
+		"mov	%w[prob" #a "], (%[probs_base], %q[t1], 1)\n\t"
+
+// NOTE: The order of variables in __asm__ can affect speed and code size.
+#define rc_asm_bittree_n(probs_base_var, final_add, asm_str) \
+do { \
+	uint32_t t0; \
+	uint32_t t1; \
+	uint32_t t_prob0; \
+	uint32_t t_prob1; \
+	\
+	__asm__( \
+		asm_str \
+		: \
+		[range]     "+&r"(rc.range), \
+		[code]      "+&r"(rc.code), \
+		[t0]        "=&r"(t0), \
+		[t1]        "=&r"(t1), \
+		[prob0]     "=&r"(t_prob0), \
+		[prob1]     "=&r"(t_prob1), \
+		[symbol]    "=&r"(symbol), \
+		[in_ptr]    "+&r"(rc_in_ptr) \
+		: \
+		[probs_base]           "r"(probs_base_var), \
+		[last_sbb]             "n"(-1 - (final_add)), \
+		[top_value]            "n"(RC_TOP_VALUE), \
+		[shift_bits]           "n"(RC_SHIFT_BITS), \
+		[bit_model_total_bits] "n"(RC_BIT_MODEL_TOTAL_BITS), \
+		[bit_model_offset]     "n"(RC_BIT_MODEL_OFFSET), \
+		[move_bits]            "n"(RC_MOVE_BITS) \
+		: \
+		"cc", "memory"); \
+} while (0)
+
+
+#if LZMA_RANGE_DECODER_CONFIG & 0x010
+#undef rc_bittree3
+#define rc_bittree3(probs_base_var, final_add) \
+	rc_asm_bittree_n(probs_base_var, final_add, \
+		rc_asm_bittree(0, 1, rc_asm_y, rc_asm_n, rc_asm_n) \
+		rc_asm_bittree(1, 0, rc_asm_n, rc_asm_y, rc_asm_n) \
+		rc_asm_bittree(0, 1, rc_asm_n, rc_asm_n, rc_asm_y) \
+	)
+
+#undef rc_bittree6
+#define rc_bittree6(probs_base_var, final_add) \
+	rc_asm_bittree_n(probs_base_var, final_add, \
+		rc_asm_bittree(0, 1, rc_asm_y, rc_asm_n, rc_asm_n) \
+		rc_asm_bittree(1, 0, rc_asm_n, rc_asm_y, rc_asm_n) \
+		rc_asm_bittree(0, 1, rc_asm_n, rc_asm_y, rc_asm_n) \
+		rc_asm_bittree(1, 0, rc_asm_n, rc_asm_y, rc_asm_n) \
+		rc_asm_bittree(0, 1, rc_asm_n, rc_asm_y, rc_asm_n) \
+		rc_asm_bittree(1, 0, rc_asm_n, rc_asm_n, rc_asm_y) \
+	)
+
+#undef rc_bittree8
+#define rc_bittree8(probs_base_var, final_add) \
+	rc_asm_bittree_n(probs_base_var, final_add, \
+		rc_asm_bittree(0, 1, rc_asm_y, rc_asm_n, rc_asm_n) \
+		rc_asm_bittree(1, 0, rc_asm_n, rc_asm_y, rc_asm_n) \
+		rc_asm_bittree(0, 1, rc_asm_n, rc_asm_y, rc_asm_n) \
+		rc_asm_bittree(1, 0, rc_asm_n, rc_asm_y, rc_asm_n) \
+		rc_asm_bittree(0, 1, rc_asm_n, rc_asm_y, rc_asm_n) \
+		rc_asm_bittree(1, 0, rc_asm_n, rc_asm_y, rc_asm_n) \
+		rc_asm_bittree(0, 1, rc_asm_n, rc_asm_y, rc_asm_n) \
+		rc_asm_bittree(1, 0, rc_asm_n, rc_asm_n, rc_asm_y) \
+	)
+#endif // LZMA_RANGE_DECODER_CONFIG & 0x010
+
+
+// Fixed-sized reverse bittree
+//
+// This uses the indexing that constructs the final value in symbol directly.
+// add    = 1,  2,   4,  8
+// dcur   = -,  4,   8, 16
+// dnext0 = 4,   8, 16,  -
+// dnext0 = 6,  12, 24,  -
+#define rc_asm_bittree_rev(a, b, add, dcur, dnext0, dnext1, \
+		first_only, middle_only, last_only) \
+	first_only( \
+		"movzw	2(%[probs_base]), %[prob" #a "]\n\t" \
+		"xor	%[symbol], %[symbol]\n\t" \
+		"movzw	4(%[probs_base]), %[prob" #b "]\n\t" \
+	) \
+	middle_only( \
+		"movzw	" #dnext0 "(%[probs_base], %q[symbol], 2), " \
+			"%[prob" #b "]\n\t" \
+	) \
+		\
+		rc_asm_normalize \
+		rc_asm_calc("prob" #a) \
+		\
+		"cmovae	%[t0], %[range]\n\t" \
+		\
+	first_only( \
+		"movzw	6(%[probs_base]), %[t0]\n\t" \
+		"cmovae	%[t0], %[prob" #b "]\n\t" \
+	) \
+	middle_only( \
+		"movzw	" #dnext1 "(%[probs_base], %q[symbol], 2), %[t0]\n\t" \
+		"cmovae	%[t0], %[prob" #b "]\n\t" \
+	) \
+		\
+		"lea	" #add "(%q[symbol]), %[t0]\n\t" \
+		"cmovb	%[t1], %[code]\n\t" \
+	middle_only( \
+		"mov	%[symbol], %[t1]\n\t" \
+	) \
+	last_only( \
+		"mov	%[symbol], %[t1]\n\t" \
+	) \
+		"cmovae	%[t0], %[symbol]\n\t" \
+		"lea	%c[bit_model_offset](%q[prob" #a "]), %[t0]\n\t" \
+		"cmovae	%[prob" #a "], %[t0]\n\t" \
+		\
+		"shr	%[move_bits], %[t0]\n\t" \
+		"sub	%[t0], %[prob" #a "]\n\t" \
+	first_only( \
+		"mov	%w[prob" #a "], 2(%[probs_base])\n\t" \
+	) \
+	middle_only( \
+		"mov	%w[prob" #a "], " \
+			#dcur "(%[probs_base], %q[t1], 2)\n\t" \
+	) \
+	last_only( \
+		"mov	%w[prob" #a "], " \
+			#dcur "(%[probs_base], %q[t1], 2)\n\t" \
+	)
+
+#if LZMA_RANGE_DECODER_CONFIG & 0x020
+#undef rc_bittree_rev4
+#define rc_bittree_rev4(probs_base_var) \
+rc_asm_bittree_n(probs_base_var, 4, \
+	rc_asm_bittree_rev(0, 1, 1,  -,  4,  6, rc_asm_y, rc_asm_n, rc_asm_n) \
+	rc_asm_bittree_rev(1, 0, 2,  4,  8, 12, rc_asm_n, rc_asm_y, rc_asm_n) \
+	rc_asm_bittree_rev(0, 1, 4,  8, 16, 24, rc_asm_n, rc_asm_y, rc_asm_n) \
+	rc_asm_bittree_rev(1, 0, 8, 16,  -,  -, rc_asm_n, rc_asm_n, rc_asm_y) \
+)
+#endif // LZMA_RANGE_DECODER_CONFIG & 0x020
+
+
+#if LZMA_RANGE_DECODER_CONFIG & 0x040
+#undef rc_bit_add_if_1
+#define rc_bit_add_if_1(probs_base_var, dest_var, value_to_add_if_1) \
+do { \
+	uint32_t t0; \
+	uint32_t t1; \
+	uint32_t t2 = (value_to_add_if_1); \
+	uint32_t t_prob; \
+	uint32_t t_index; \
+	\
+	__asm__( \
+		"movzw	(%[probs_base], %q[symbol], 2), %[prob]\n\t" \
+		"mov	%[symbol], %[index]\n\t" \
+		\
+		"add	%[dest], %[t2]\n\t" \
+		"add	%[symbol], %[symbol]\n\t" \
+		\
+		rc_asm_normalize \
+		rc_asm_calc("prob") \
+		\
+		"cmovae	%[t0], %[range]\n\t" \
+		"lea	%c[bit_model_offset](%q[prob]), %[t0]\n\t" \
+		"cmovb	%[t1], %[code]\n\t" \
+		"cmovae	%[prob], %[t0]\n\t" \
+		\
+		"cmovae	%[t2], %[dest]\n\t" \
+		"sbb	$-1, %[symbol]\n\t" \
+		\
+		"sar	%[move_bits], %[t0]\n\t" \
+		"sub	%[t0], %[prob]\n\t" \
+		"mov	%w[prob], (%[probs_base], %q[index], 2)" \
+		: \
+		[range]     "+&r"(rc.range), \
+		[code]      "+&r"(rc.code), \
+		[t0]        "=&r"(t0), \
+		[t1]        "=&r"(t1), \
+		[prob]      "=&r"(t_prob), \
+		[index]     "=&r"(t_index), \
+		[symbol]    "+&r"(symbol), \
+		[t2]        "+&r"(t2), \
+		[dest]      "+&r"(dest_var), \
+		[in_ptr]    "+&r"(rc_in_ptr) \
+		: \
+		[probs_base]           "r"(probs_base_var), \
+		[top_value]            "n"(RC_TOP_VALUE), \
+		[shift_bits]           "n"(RC_SHIFT_BITS), \
+		[bit_model_total_bits] "n"(RC_BIT_MODEL_TOTAL_BITS), \
+		[bit_model_offset]     "n"(RC_BIT_MODEL_OFFSET), \
+		[move_bits]            "n"(RC_MOVE_BITS) \
+		: \
+		"cc", "memory"); \
+} while (0)
+#endif // LZMA_RANGE_DECODER_CONFIG & 0x040
+
+
+// Literal decoding uses a normal 8-bit bittree but literal with match byte
+// is more complex in picking the probability variable from the correct
+// subtree. This doesn't use preloading/prefetching of the next prob because
+// there are four choices instead of two.
+//
+// FIXME? The first iteration starts with symbol = 1 so it could be optimized
+// by a tiny amount.
+#define rc_asm_matched_literal(nonlast_only) \
+		"add	%[offset], %[symbol]\n\t" \
+		"and	%[offset], %[match_bit]\n\t" \
+		"add	%[match_bit], %[symbol]\n\t" \
+		\
+		"movzw	(%[probs_base], %q[symbol], 2), %[prob]\n\t" \
+		\
+		"add	%[symbol], %[symbol]\n\t" \
+		\
+	nonlast_only( \
+		"xor	%[match_bit], %[offset]\n\t" \
+		"add	%[match_byte], %[match_byte]\n\t" \
+	) \
+		\
+		rc_asm_normalize \
+		rc_asm_calc("prob") \
+		\
+		"cmovae	%[t0], %[range]\n\t" \
+		"lea	%c[bit_model_offset](%q[prob]), %[t0]\n\t" \
+		"cmovb	%[t1], %[code]\n\t" \
+		"mov	%[symbol], %[t1]\n\t" \
+		"cmovae	%[prob], %[t0]\n\t" \
+		\
+	nonlast_only( \
+		"cmovae	%[match_bit], %[offset]\n\t" \
+		"mov	%[match_byte], %[match_bit]\n\t" \
+	) \
+		\
+		"sbb	$-1, %[symbol]\n\t" \
+		\
+		"shr	%[move_bits], %[t0]\n\t" \
+		/* Undo symbol += match_bit + offset: */ \
+		"and	$0x1FF, %[symbol]\n\t" \
+		"sub	%[t0], %[prob]\n\t" \
+		\
+		/* Scaling of 1 instead of 2 because symbol <<= 1. */ \
+		"mov	%w[prob], (%[probs_base], %q[t1], 1)\n\t"
+
+
+#if LZMA_RANGE_DECODER_CONFIG & 0x080
+#undef rc_matched_literal
+#define rc_matched_literal(probs_base_var, match_byte_value) \
+do { \
+	uint32_t t0; \
+	uint32_t t1; \
+	uint32_t t_prob; \
+	uint32_t t_match_byte = (uint32_t)(match_byte_value) << 1; \
+	uint32_t t_match_bit = t_match_byte; \
+	uint32_t t_offset = 0x100; \
+	symbol = 1; \
+	\
+	__asm__( \
+		rc_asm_matched_literal(rc_asm_y) \
+		rc_asm_matched_literal(rc_asm_y) \
+		rc_asm_matched_literal(rc_asm_y) \
+		rc_asm_matched_literal(rc_asm_y) \
+		rc_asm_matched_literal(rc_asm_y) \
+		rc_asm_matched_literal(rc_asm_y) \
+		rc_asm_matched_literal(rc_asm_y) \
+		rc_asm_matched_literal(rc_asm_n) \
+		: \
+		[range]       "+&r"(rc.range), \
+		[code]        "+&r"(rc.code), \
+		[t0]          "=&r"(t0), \
+		[t1]          "=&r"(t1), \
+		[prob]        "=&r"(t_prob), \
+		[match_bit]   "+&r"(t_match_bit), \
+		[symbol]      "+&r"(symbol), \
+		[match_byte]  "+&r"(t_match_byte), \
+		[offset]      "+&r"(t_offset), \
+		[in_ptr]      "+&r"(rc_in_ptr) \
+		: \
+		[probs_base]           "r"(probs_base_var), \
+		[top_value]            "n"(RC_TOP_VALUE), \
+		[shift_bits]           "n"(RC_SHIFT_BITS), \
+		[bit_model_total_bits] "n"(RC_BIT_MODEL_TOTAL_BITS), \
+		[bit_model_offset]     "n"(RC_BIT_MODEL_OFFSET), \
+		[move_bits]            "n"(RC_MOVE_BITS) \
+		: \
+		"cc", "memory"); \
+} while (0)
+#endif // LZMA_RANGE_DECODER_CONFIG & 0x080
+
+
+// Doing the loop in asm instead of C seems to help a little.
+#if LZMA_RANGE_DECODER_CONFIG & 0x100
+#undef rc_direct
+#define rc_direct(dest_var, count_var) \
+do { \
+	uint32_t t0; \
+	uint32_t t1; \
+	\
+	__asm__( \
+		"2:\n\t" \
+		"add	%[dest], %[dest]\n\t" \
+		"lea	1(%q[dest]), %[t1]\n\t" \
+		\
+		rc_asm_normalize \
+		\
+		"shr	$1, %[range]\n\t" \
+		"mov	%[code], %[t0]\n\t" \
+		"sub	%[range], %[code]\n\t" \
+		"cmovns	%[t1], %[dest]\n\t" \
+		"cmovs	%[t0], %[code]\n\t" \
+		"dec	%[count]\n\t" \
+		"jnz	2b\n\t" \
+		: \
+		[range]       "+&r"(rc.range), \
+		[code]        "+&r"(rc.code), \
+		[t0]          "=&r"(t0), \
+		[t1]          "=&r"(t1), \
+		[dest]        "+&r"(dest_var), \
+		[count]       "+&r"(count_var), \
+		[in_ptr]      "+&r"(rc_in_ptr) \
+		: \
+		[top_value]   "n"(RC_TOP_VALUE), \
+		[shift_bits]  "n"(RC_SHIFT_BITS) \
+		: \
+		"cc", "memory"); \
+} while (0)
+#endif // LZMA_RANGE_DECODER_CONFIG & 0x100
+
+#endif // x86_64
 
 #endif