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Use common helper functions for unaligned loads.

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This commit is contained in:
Mike Pall 2011-05-09 18:09:29 +02:00
parent d9c1f771a7
commit 28e87d33e9
3 changed files with 34 additions and 23 deletions
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26
src/lj_def.h
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@ -184,6 +184,28 @@ static LJ_AINLINE uint64_t lj_bswap64(uint64_t x)
#error "missing define for lj_bswap()"
#endif
typedef union __attribute__((packed)) Unaligned16 {
uint16_t u;
uint8_t b[2];
} Unaligned16;
typedef union __attribute__((packed)) Unaligned32 {
uint32_t u;
uint8_t b[4];
} Unaligned32;
/* Unaligned load of uint16_t. */
static LJ_AINLINE uint16_t lj_getu16(const void *p)
{
return ((const Unaligned16 *)p)->u;
}
/* Unaligned load of uint32_t. */
static LJ_AINLINE uint32_t lj_getu32(const void *p)
{
return ((const Unaligned32 *)p)->u;
}
#elif defined(_MSC_VER)
#define LJ_NORET __declspec(noreturn)
@ -208,6 +230,10 @@ static LJ_AINLINE uint32_t lj_fls(uint32_t x)
#define lj_bswap(x) (_byteswap_ulong((x)))
#define lj_bswap64(x) (_byteswap_uint64((x)))
/* MSVC is only supported on x86/x64, where unaligned loads are always ok. */
#define lj_getu16(p) (*(uint16_t *)(p))
#define lj_getu32(p) (*(uint32_t *)(p))
#else
#error "missing defines for your compiler"
#endif

9
src/lj_opt_fold.c
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@ -1647,16 +1647,13 @@ LJFOLDF(comm_bxor)
static TRef kfold_xload(jit_State *J, IRIns *ir, const void *p)
{
int32_t k;
#if !LJ_TARGET_X86ORX64
#error "Missing support for unaligned loads"
#endif
switch (irt_type(ir->t)) {
case IRT_NUM: return lj_ir_knum_u64(J, *(uint64_t *)p);
case IRT_I8: k = (int32_t)*(int8_t *)p; break;
case IRT_U8: k = (int32_t)*(uint8_t *)p; break;
case IRT_I16: k = (int32_t)*(int16_t *)p; break;
case IRT_U16: k = (int32_t)*(uint16_t *)p; break;
case IRT_INT: case IRT_U32: k = *(int32_t *)p; break;
case IRT_I16: k = (int32_t)(int16_t)lj_getu16(p); break;
case IRT_U16: k = (int32_t)(uint16_t)lj_getu16(p); break;
case IRT_INT: case IRT_U32: k = (int32_t)lj_getu32(p); break;
case IRT_I64: case IRT_U64: return lj_ir_kint64(J, *(uint64_t *)p);
default: return 0;
}

22
src/lj_str.c
View File

@ -43,18 +43,6 @@ int32_t LJ_FASTCALL lj_str_cmp(GCstr *a, GCstr *b)
return (int32_t)(a->len - b->len);
}
typedef union
#ifdef __GNUC__
__attribute__((packed))
#endif
Unaligned32 { uint32_t u; uint8_t b[4]; } Unaligned32;
/* Unaligned read of uint32_t. */
static LJ_AINLINE uint32_t str_getu32(const void *p)
{
return ((const Unaligned32 *)p)->u;
}
/* Fast string data comparison. Caveat: unaligned access to 1st string! */
static LJ_AINLINE int str_fastcmp(const char *a, const char *b, MSize len)
{
@ -62,7 +50,7 @@ static LJ_AINLINE int str_fastcmp(const char *a, const char *b, MSize len)
lua_assert(len > 0);
lua_assert((((uintptr_t)a + len) & (LJ_PAGESIZE-1)) <= LJ_PAGESIZE-4);
do { /* Note: innocuous access up to end of string + 3. */
uint32_t v = str_getu32(a+i) ^ *(const uint32_t *)(b+i);
uint32_t v = lj_getu32(a+i) ^ *(const uint32_t *)(b+i);
if (v) {
i -= len;
#if LJ_LE
@ -115,11 +103,11 @@ GCstr *lj_str_new(lua_State *L, const char *str, size_t lenx)
g = G(L);
/* Compute string hash. Constants taken from lookup3 hash by Bob Jenkins. */
if (len >= 4) { /* Caveat: unaligned access! */
a = str_getu32(str);
h ^= str_getu32(str+len-4);
b = str_getu32(str+(len>>1)-2);
a = lj_getu32(str);
h ^= lj_getu32(str+len-4);
b = lj_getu32(str+(len>>1)-2);
h ^= b; h -= lj_rol(b, 14);
b += str_getu32(str+(len>>2)-1);
b += lj_getu32(str+(len>>2)-1);
} else if (len > 0) {
a = *(const uint8_t *)str;
h ^= *(const uint8_t *)(str+len-1);