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8205004: AArch64: fix failures in jtreg ArraysEqCmpTest

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Reviewed-by: aph
This commit is contained in:
Joshua Zhu 2018-06-22 18:48:36 +03:00 committed by Dmitrij Pochepko
parent 578576f523
commit e41ac0b971
1 changed files with 22 additions and 32 deletions
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54
src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp
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@ -4928,9 +4928,8 @@ void MacroAssembler::has_negatives(Register ary1, Register len, Register result)
void MacroAssembler::arrays_equals(Register a1, Register a2, Register tmp3,
Register tmp4, Register tmp5, Register result,
Register cnt1, int elem_size)
{
Label DONE;
Register cnt1, int elem_size) {
Label DONE, SAME;
Register tmp1 = rscratch1;
Register tmp2 = rscratch2;
Register cnt2 = tmp2; // cnt2 only used in array length compare
@ -4952,21 +4951,21 @@ void MacroAssembler::arrays_equals(Register a1, Register a2, Register tmp3,
BLOCK_COMMENT(comment);
}
#endif
// if (a1 == a2)
// return true;
cmpoop(a1, a2); // May have read barriers for a1 and a2.
br(EQ, SAME);
if (UseSimpleArrayEquals) {
Label NEXT_WORD, SHORT, SAME, TAIL03, TAIL01, A_MIGHT_BE_NULL, A_IS_NOT_NULL;
// if (a1==a2)
// return true;
// if (a==null || a2==null)
Label NEXT_WORD, SHORT, TAIL03, TAIL01, A_MIGHT_BE_NULL, A_IS_NOT_NULL;
// if (a1 == null || a2 == null)
// return false;
// a1 & a2 == 0 means (some-pointer is null) or
// (very-rare-or-even-probably-impossible-pointer-values)
// so, we can save one branch in most cases
cmpoop(a1, a2);
br(EQ, SAME);
eor(rscratch1, a1, a2);
tst(a1, a2);
mov(result, false);
cbz(rscratch1, SAME);
br(EQ, A_MIGHT_BE_NULL);
// if (a1.length != a2.length)
// return false;
@ -5032,22 +5031,18 @@ void MacroAssembler::arrays_equals(Register a1, Register a2, Register tmp3,
cbnzw(tmp5, DONE);
}
}
bind(SAME);
mov(result, true);
} else {
Label NEXT_DWORD, A_IS_NULL, SHORT, TAIL, TAIL2, STUB, EARLY_OUT,
CSET_EQ, LAST_CHECK, LEN_IS_ZERO, SAME;
cbz(a1, A_IS_NULL);
ldrw(cnt1, Address(a1, length_offset));
cbz(a2, A_IS_NULL);
ldrw(cnt2, Address(a2, length_offset));
Label NEXT_DWORD, SHORT, TAIL, TAIL2, STUB, EARLY_OUT,
CSET_EQ, LAST_CHECK;
mov(result, false);
cbz(a1, DONE);
ldrw(cnt1, Address(a1, length_offset));
cbz(a2, DONE);
ldrw(cnt2, Address(a2, length_offset));
// on most CPUs a2 is still "locked"(surprisingly) in ldrw and it's
// faster to perform another branch before comparing a1 and a2
cmp(cnt1, elem_per_word);
br(LE, SHORT); // short or same
cmpoop(a1, a2);
br(EQ, SAME);
ldr(tmp3, Address(pre(a1, base_offset)));
cmp(cnt1, stubBytesThreshold);
br(GE, STUB);
@ -5099,23 +5094,15 @@ void MacroAssembler::arrays_equals(Register a1, Register a2, Register tmp3,
trampoline_call(stub);
b(DONE);
bind(SAME);
mov(result, true);
b(DONE);
bind(A_IS_NULL);
// a1 or a2 is null. if a2 == a2 then return true. else return false
cmp(a1, a2);
b(CSET_EQ);
bind(EARLY_OUT);
// (a1 != null && a2 == null) || (a1 != null && a2 != null && a1 == a2)
// so, if a2 == null => return false(0), else return true, so we can return a2
mov(result, a2);
b(DONE);
bind(LEN_IS_ZERO);
cmp(cnt2, zr);
b(CSET_EQ);
bind(SHORT);
cbz(cnt1, LEN_IS_ZERO);
cmp(cnt2, cnt1);
br(NE, DONE);
cbz(cnt1, SAME);
sub(tmp5, zr, cnt1, LSL, 3 + log_elem_size);
ldr(tmp3, Address(a1, base_offset));
ldr(tmp4, Address(a2, base_offset));
@ -5125,8 +5112,11 @@ void MacroAssembler::arrays_equals(Register a1, Register a2, Register tmp3,
cmp(tmp5, zr);
bind(CSET_EQ);
cset(result, EQ);
b(DONE);
}
bind(SAME);
mov(result, true);
// That's it.
bind(DONE);