liblzma: Set LZMA_MEMCMPLEN_EXTRA depending on the compare method.
diff --git a/src/liblzma/common/memcmplen.h b/src/liblzma/common/memcmplen.h
index f66e7cd..c1efc9e 100644
--- a/src/liblzma/common/memcmplen.h
+++ b/src/liblzma/common/memcmplen.h
@@ -19,11 +19,6 @@
# include <immintrin.h>
#endif
-/// How many extra bytes lzma_memcmplen() may read. This depends on
-/// the method but since it is just a few bytes the biggest possible
-/// value is used here.
-#define LZMA_MEMCMPLEN_EXTRA 16
-
/// Find out how many equal bytes the two buffers have.
///
@@ -39,6 +34,11 @@
///
/// \return Number of equal bytes in the buffers is returned.
/// This is always at least len and at most limit.
+///
+/// \note LZMA_MEMCMPLEN_EXTRA defines how many extra bytes may be read.
+/// It's rounded up to 2^n. This extra amount needs to be
+/// allocated in the buffers being used. It needs to be
+/// initialized too to keep Valgrind quiet.
static inline uint32_t lzma_attribute((__always_inline__))
lzma_memcmplen(const uint8_t *buf1, const uint8_t *buf2,
uint32_t len, uint32_t limit)
@@ -59,6 +59,7 @@
// to be a good method. This may be fine on other 64-bit CPUs too.
// On big endian one should use xor instead of subtraction and switch
// to __builtin_clzll().
+#define LZMA_MEMCMPLEN_EXTRA 8
while (len < limit) {
const uint64_t x = *(const uint64_t *)(buf1 + len)
- *(const uint64_t *)(buf2 + len);
@@ -91,6 +92,7 @@
// version is sometimes significantly faster and sometimes
// slightly slower than this SSE2 version, so this SSE2
// version isn't used on x86-64.
+# define LZMA_MEMCMPLEN_EXTRA 16
while (len < limit) {
const uint32_t x = 0xFFFF ^ _mm_movemask_epi8(_mm_cmpeq_epi8(
_mm_loadu_si128((const __m128i *)(buf1 + len)),
@@ -116,6 +118,7 @@
#elif defined(TUKLIB_FAST_UNALIGNED_ACCESS) && !defined(WORDS_BIGENDIAN)
// Generic 32-bit little endian method
+# define LZMA_MEMCMPLEN_EXTRA 4
while (len < limit) {
uint32_t x = *(const uint32_t *)(buf1 + len)
- *(const uint32_t *)(buf2 + len);
@@ -138,6 +141,7 @@
#elif defined(TUKLIB_FAST_UNALIGNED_ACCESS) && defined(WORDS_BIGENDIAN)
// Generic 32-bit big endian method
+# define LZMA_MEMCMPLEN_EXTRA 4
while (len < limit) {
uint32_t x = *(const uint32_t *)(buf1 + len)
^ *(const uint32_t *)(buf2 + len);
@@ -160,6 +164,7 @@
#else
// Simple portable version that doesn't use unaligned access.
+# define LZMA_MEMCMPLEN_EXTRA 0
while (len < limit && buf1[len] == buf2[len])
++len;
