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ARM: Don't generate unaligned XLOADs.

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This commit is contained in:
Mike Pall 2011-06-02 01:46:23 +02:00
parent a770bf3741
commit fff2fb31f9
1 changed files with 12 additions and 3 deletions
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15
src/lj_opt_fold.c
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@ -1679,7 +1679,7 @@ static TRef kfold_xload(jit_State *J, IRIns *ir, const void *p)
/* Turn: string.sub(str, a, b) == kstr
** into: string.byte(str, a) == string.byte(kstr, 1) etc.
** Note: this creates unaligned XLOADs!
** Note: this creates unaligned XLOADs on x86/x64.
*/
LJFOLD(EQ SNEW KGC)
LJFOLD(NE SNEW KGC)
@ -1688,7 +1688,16 @@ LJFOLDF(merge_eqne_snew_kgc)
GCstr *kstr = ir_kstr(fright);
int32_t len = (int32_t)kstr->len;
lua_assert(irt_isstr(fins->t));
if (len <= 4) { /* Handle string lengths 0, 1, 2, 3, 4. */
#if LJ_TARGET_X86ORX64
#define FOLD_SNEW_MAX_LEN 4 /* Handle string lengths 0, 1, 2, 3, 4. */
#define FOLD_SNEW_TYPE8 IRT_I8 /* Creates shorter immediates. */
#else
#define FOLD_SNEW_MAX_LEN 1 /* Handle string lengths 0 or 1. */
#define FOLD_SNEW_TYPE8 IRT_U8 /* Prefer unsigned loads. */
#endif
if (len <= FOLD_SNEW_MAX_LEN) {
IROp op = (IROp)fins->o;
IRRef strref = fleft->op1;
lua_assert(IR(strref)->o == IR_STRREF);
@ -1704,7 +1713,7 @@ LJFOLDF(merge_eqne_snew_kgc)
}
if (len > 0) {
/* A 4 byte load for length 3 is ok -- all strings have an extra NUL. */
uint16_t ot = (uint16_t)(len == 1 ? IRT(IR_XLOAD, IRT_I8) :
uint16_t ot = (uint16_t)(len == 1 ? IRT(IR_XLOAD, FOLD_SNEW_TYPE8) :
len == 2 ? IRT(IR_XLOAD, IRT_U16) :
IRTI(IR_XLOAD));
TRef tmp = emitir(ot, strref,