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8146801: Allocating short arrays of non-constant size is slow

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Reviewed-by: kvn, twisti, vlivanov
This commit is contained in:
Aleksey Shipilev 2016-03-04 01:30:11 +03:00
parent 548530cf08
commit 103aff334f
17 changed files with 150 additions and 53 deletions
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35
hotspot/src/cpu/x86/vm/macroAssembler_x86.cpp
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@ -7198,21 +7198,50 @@ void MacroAssembler::verified_entry(int framesize, int stack_bang_size, bool fp_
}
void MacroAssembler::clear_mem(Register base, Register cnt, Register tmp) {
void MacroAssembler::clear_mem(Register base, Register cnt, Register tmp, bool is_large) {
// cnt - number of qwords (8-byte words).
// base - start address, qword aligned.
// is_large - if optimizers know cnt is larger than InitArrayShortSize
assert(base==rdi, "base register must be edi for rep stos");
assert(tmp==rax, "tmp register must be eax for rep stos");
assert(cnt==rcx, "cnt register must be ecx for rep stos");
assert(InitArrayShortSize % BytesPerLong == 0,
"InitArrayShortSize should be the multiple of BytesPerLong");
Label DONE;
xorptr(tmp, tmp);
if (!is_large) {
Label LOOP, LONG;
cmpptr(cnt, InitArrayShortSize/BytesPerLong);
jccb(Assembler::greater, LONG);
NOT_LP64(shlptr(cnt, 1);) // convert to number of 32-bit words for 32-bit VM
decrement(cnt);
jccb(Assembler::negative, DONE); // Zero length
// Use individual pointer-sized stores for small counts:
BIND(LOOP);
movptr(Address(base, cnt, Address::times_ptr), tmp);
decrement(cnt);
jccb(Assembler::greaterEqual, LOOP);
jmpb(DONE);
BIND(LONG);
}
// Use longer rep-prefixed ops for non-small counts:
if (UseFastStosb) {
shlptr(cnt,3); // convert to number of bytes
shlptr(cnt, 3); // convert to number of bytes
rep_stosb();
} else {
NOT_LP64(shlptr(cnt,1);) // convert to number of dwords for 32-bit VM
NOT_LP64(shlptr(cnt, 1);) // convert to number of 32-bit words for 32-bit VM
rep_stos();
}
BIND(DONE);
}
#ifdef COMPILER2