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

Browse source 
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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3
hotspot/src/cpu/aarch64/vm/aarch64.ad
View file

@ -3425,9 +3425,6 @@ const bool Matcher::misaligned_vectors_ok() {
// false => size gets scaled to BytesPerLong, ok.
const bool Matcher::init_array_count_is_in_bytes = false;
// Threshold size for cleararray.
const int Matcher::init_array_short_size = 18 * BytesPerLong;
// Use conditional move (CMOVL)
const int Matcher::long_cmove_cost() {
// long cmoves are no more expensive than int cmoves

2
hotspot/src/cpu/aarch64/vm/globals_aarch64.hpp
View file

@ -76,6 +76,8 @@ define_pd_global(bool, CompactStrings, false);
// avoid biased locking while we are bootstrapping the aarch64 build
define_pd_global(bool, UseBiasedLocking, false);
define_pd_global(intx, InitArrayShortSize, 18*BytesPerLong);
#if defined(COMPILER1) || defined(COMPILER2)
define_pd_global(intx, InlineSmallCode, 1000);
#endif

2
hotspot/src/cpu/ppc/vm/globals_ppc.hpp
View file

@ -76,6 +76,8 @@ define_pd_global(uintx, TypeProfileLevel, 111);
define_pd_global(bool, CompactStrings, true);
define_pd_global(intx, InitArrayShortSize, 8*BytesPerLong);
// Platform dependent flag handling: flags only defined on this platform.
#define ARCH_FLAGS(develop, product, diagnostic, experimental, notproduct, range, constraint) \
\

2
hotspot/src/cpu/ppc/vm/ppc.ad
View file

@ -2137,8 +2137,6 @@ MachTypeNode *Matcher::make_decode_node() {
return decode;
}
*/
// Threshold size for cleararray.
const int Matcher::init_array_short_size = 8 * BytesPerLong;
// false => size gets scaled to BytesPerLong, ok.
const bool Matcher::init_array_count_is_in_bytes = false;

2
hotspot/src/cpu/sparc/vm/globals_sparc.hpp
View file

@ -90,6 +90,8 @@ define_pd_global(uintx, TypeProfileLevel, 111);
define_pd_global(bool, CompactStrings, true);
define_pd_global(intx, InitArrayShortSize, 8*BytesPerLong);
#define ARCH_FLAGS(develop, product, diagnostic, experimental, notproduct, range, constraint) \
\
product(intx, UseVIS, 99, \

3
hotspot/src/cpu/sparc/vm/sparc.ad
View file

@ -1980,9 +1980,6 @@ const bool Matcher::isSimpleConstant64(jlong value) {
// No scaling for the parameter the ClearArray node.
const bool Matcher::init_array_count_is_in_bytes = true;
// Threshold size for cleararray.
const int Matcher::init_array_short_size = 8 * BytesPerLong;
// No additional cost for CMOVL.
const int Matcher::long_cmove_cost() { return 0; }

2
hotspot/src/cpu/x86/vm/globals_x86.hpp
View file

@ -97,6 +97,8 @@ define_pd_global(bool, CompactStrings, true);
define_pd_global(bool, PreserveFramePointer, false);
define_pd_global(intx, InitArrayShortSize, 8*BytesPerLong);
#define ARCH_FLAGS(develop, product, diagnostic, experimental, notproduct, range, constraint) \
\
develop(bool, IEEEPrecision, true, \

35
hotspot/src/cpu/x86/vm/macroAssembler_x86.cpp
View file

@ -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

5
hotspot/src/cpu/x86/vm/macroAssembler_x86.hpp
View file

@ -1284,8 +1284,9 @@ public:
// C2 compiled method's prolog code.
void verified_entry(int framesize, int stack_bang_size, bool fp_mode_24b);
// clear memory of size 'cnt' qwords, starting at 'base'.
void clear_mem(Register base, Register cnt, Register rtmp);
// clear memory of size 'cnt' qwords, starting at 'base';
// if 'is_large' is set, do not try to produce short loop
void clear_mem(Register base, Register cnt, Register rtmp, bool is_large);
#ifdef COMPILER2
void string_indexof_char(Register str1, Register cnt1, Register ch, Register result,

52
hotspot/src/cpu/x86/vm/x86_32.ad
View file

@ -1420,9 +1420,6 @@ const bool Matcher::isSimpleConstant64(jlong value) {
// The ecx parameter to rep stos for the ClearArray node is in dwords.
const bool Matcher::init_array_count_is_in_bytes = false;
// Threshold size for cleararray.
const int Matcher::init_array_short_size = 8 * BytesPerLong;
// Needs 2 CMOV's for longs.
const int Matcher::long_cmove_cost() { return 1; }
@ -11369,27 +11366,54 @@ instruct MoveL2D_reg_reg_sse(regD dst, eRegL src, regD tmp) %{
// =======================================================================
// fast clearing of an array
instruct rep_stos(eCXRegI cnt, eDIRegP base, eAXRegI zero, Universe dummy, eFlagsReg cr) %{
predicate(!UseFastStosb);
predicate(!((ClearArrayNode*)n)->is_large());
match(Set dummy (ClearArray cnt base));
effect(USE_KILL cnt, USE_KILL base, KILL zero, KILL cr);
format %{ "XOR EAX,EAX\t# ClearArray:\n\t"
"SHL ECX,1\t# Convert doublewords to words\n\t"
"REP STOS\t# store EAX into [EDI++] while ECX--" %}
format %{ $$template
$$emit$$"XOR EAX,EAX\t# ClearArray:\n\t"
$$emit$$"CMP InitArrayShortSize,rcx\n\t"
$$emit$$"JG LARGE\n\t"
$$emit$$"SHL ECX, 1\n\t"
$$emit$$"DEC ECX\n\t"
$$emit$$"JS DONE\t# Zero length\n\t"
$$emit$$"MOV EAX,(EDI,ECX,4)\t# LOOP\n\t"
$$emit$$"DEC ECX\n\t"
$$emit$$"JGE LOOP\n\t"
$$emit$$"JMP DONE\n\t"
$$emit$$"# LARGE:\n\t"
if (UseFastStosb) {
$$emit$$"SHL ECX,3\t# Convert doublewords to bytes\n\t"
$$emit$$"REP STOSB\t# store EAX into [EDI++] while ECX--\n\t"
} else {
$$emit$$"SHL ECX,1\t# Convert doublewords to words\n\t"
$$emit$$"REP STOS\t# store EAX into [EDI++] while ECX--\n\t"
}
$$emit$$"# DONE"
%}
ins_encode %{
__ clear_mem($base$$Register, $cnt$$Register, $zero$$Register);
__ clear_mem($base$$Register, $cnt$$Register, $zero$$Register, false);
%}
ins_pipe( pipe_slow );
%}
instruct rep_fast_stosb(eCXRegI cnt, eDIRegP base, eAXRegI zero, Universe dummy, eFlagsReg cr) %{
predicate(UseFastStosb);
instruct rep_stos_large(eCXRegI cnt, eDIRegP base, eAXRegI zero, Universe dummy, eFlagsReg cr) %{
predicate(((ClearArrayNode*)n)->is_large());
match(Set dummy (ClearArray cnt base));
effect(USE_KILL cnt, USE_KILL base, KILL zero, KILL cr);
format %{ "XOR EAX,EAX\t# ClearArray:\n\t"
"SHL ECX,3\t# Convert doublewords to bytes\n\t"
"REP STOSB\t# store EAX into [EDI++] while ECX--" %}
format %{ $$template
$$emit$$"XOR EAX,EAX\t# ClearArray:\n\t"
if (UseFastStosb) {
$$emit$$"SHL ECX,3\t# Convert doublewords to bytes\n\t"
$$emit$$"REP STOSB\t# store EAX into [EDI++] while ECX--\n\t"
} else {
$$emit$$"SHL ECX,1\t# Convert doublewords to words\n\t"
$$emit$$"REP STOS\t# store EAX into [EDI++] while ECX--\n\t"
}
$$emit$$"# DONE"
%}
ins_encode %{
__ clear_mem($base$$Register, $cnt$$Register, $zero$$Register);
__ clear_mem($base$$Register, $cnt$$Register, $zero$$Register, true);
%}
ins_pipe( pipe_slow );
%}

51
hotspot/src/cpu/x86/vm/x86_64.ad
View file

@ -1637,9 +1637,6 @@ const bool Matcher::isSimpleConstant64(jlong value) {
// The ecx parameter to rep stosq for the ClearArray node is in words.
const bool Matcher::init_array_count_is_in_bytes = false;
// Threshold size for cleararray.
const int Matcher::init_array_short_size = 8 * BytesPerLong;
// No additional cost for CMOVL.
const int Matcher::long_cmove_cost() { return 0; }
@ -10460,31 +10457,55 @@ instruct MoveL2D_reg_reg(regD dst, rRegL src) %{
instruct rep_stos(rcx_RegL cnt, rdi_RegP base, rax_RegI zero, Universe dummy,
rFlagsReg cr)
%{
predicate(!UseFastStosb);
predicate(!((ClearArrayNode*)n)->is_large());
match(Set dummy (ClearArray cnt base));
effect(USE_KILL cnt, USE_KILL base, KILL zero, KILL cr);
format %{ "xorq rax, rax\t# ClearArray:\n\t"
"rep stosq\t# Store rax to *rdi++ while rcx--" %}
format %{ $$template
$$emit$$"xorq rax, rax\t# ClearArray:\n\t"
$$emit$$"cmp InitArrayShortSize,rcx\n\t"
$$emit$$"jg LARGE\n\t"
$$emit$$"dec rcx\n\t"
$$emit$$"js DONE\t# Zero length\n\t"
$$emit$$"mov rax,(rdi,rcx,8)\t# LOOP\n\t"
$$emit$$"dec rcx\n\t"
$$emit$$"jge LOOP\n\t"
$$emit$$"jmp DONE\n\t"
$$emit$$"# LARGE:\n\t"
if (UseFastStosb) {
$$emit$$"shlq rcx,3\t# Convert doublewords to bytes\n\t"
$$emit$$"rep stosb\t# Store rax to *rdi++ while rcx--\n\t"
} else {
$$emit$$"rep stosq\t# Store rax to *rdi++ while rcx--\n\t"
}
$$emit$$"# DONE"
%}
ins_encode %{
__ clear_mem($base$$Register, $cnt$$Register, $zero$$Register);
__ clear_mem($base$$Register, $cnt$$Register, $zero$$Register, false);
%}
ins_pipe(pipe_slow);
%}
instruct rep_fast_stosb(rcx_RegL cnt, rdi_RegP base, rax_RegI zero, Universe dummy,
instruct rep_stos_large(rcx_RegL cnt, rdi_RegP base, rax_RegI zero, Universe dummy,
rFlagsReg cr)
%{
predicate(UseFastStosb);
predicate(((ClearArrayNode*)n)->is_large());
match(Set dummy (ClearArray cnt base));
effect(USE_KILL cnt, USE_KILL base, KILL zero, KILL cr);
format %{ "xorq rax, rax\t# ClearArray:\n\t"
"shlq rcx,3\t# Convert doublewords to bytes\n\t"
"rep stosb\t# Store rax to *rdi++ while rcx--" %}
ins_encode %{
__ clear_mem($base$$Register, $cnt$$Register, $zero$$Register);
format %{ $$template
$$emit$$"xorq rax, rax\t# ClearArray:\n\t"
if (UseFastStosb) {
$$emit$$"shlq rcx,3\t# Convert doublewords to bytes\n\t"
$$emit$$"rep stosb\t# Store rax to *rdi++ while rcx--"
} else {
$$emit$$"rep stosq\t# Store rax to *rdi++ while rcx--"
}
%}
ins_pipe( pipe_slow );
ins_encode %{
__ clear_mem($base$$Register, $cnt$$Register, $zero$$Register, true);
%}
ins_pipe(pipe_slow);
%}
instruct string_compareL(rdi_RegP str1, rcx_RegI cnt1, rsi_RegP str2, rdx_RegI cnt2,

4
hotspot/src/share/vm/opto/matcher.hpp
View file

@ -399,10 +399,6 @@ public:
// Optional scaling for the parameter to the ClearArray/CopyArray node.
static const bool init_array_count_is_in_bytes;
// Threshold small size (in bytes) for a ClearArray/CopyArray node.
// Anything this size or smaller may get converted to discrete scalar stores.
static const int init_array_short_size;
// Some hardware needs 2 CMOV's for longs.
static const int long_cmove_cost();

14
hotspot/src/share/vm/opto/memnode.cpp
View file

@ -2741,6 +2741,9 @@ Node* ClearArrayNode::Identity(PhaseGVN* phase) {
//------------------------------Idealize---------------------------------------
// Clearing a short array is faster with stores
Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
// Already know this is a large node, do not try to ideal it
if (_is_large) return NULL;
const int unit = BytesPerLong;
const TypeX* t = phase->type(in(2))->isa_intptr_t();
if (!t) return NULL;
@ -2753,8 +2756,11 @@ Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
// (see jck test stmt114.stmt11402.val).
if (size <= 0 || size % unit != 0) return NULL;
intptr_t count = size / unit;
// Length too long; use fast hardware clear
if (size > Matcher::init_array_short_size) return NULL;
// Length too long; communicate this to matchers and assemblers.
// Assemblers are responsible to produce fast hardware clears for it.
if (size > InitArrayShortSize) {
return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
}
Node *mem = in(1);
if( phase->type(mem)==Type::TOP ) return NULL;
Node *adr = in(3);
@ -2852,7 +2858,7 @@ Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
// Bulk clear double-words
Node* zsize = phase->transform(new SubXNode(zend, zbase) );
Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
mem = new ClearArrayNode(ctl, mem, zsize, adr);
mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
return phase->transform(mem);
}
@ -3901,7 +3907,7 @@ Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
zeroes_done, zeroes_needed,
phase);
zeroes_done = zeroes_needed;
if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
do_zeroing = false; // leave the hole, next time
}
}

7
hotspot/src/share/vm/opto/memnode.hpp
View file

@ -1013,9 +1013,11 @@ public:
//------------------------------ClearArray-------------------------------------
class ClearArrayNode: public Node {
private:
bool _is_large;
public:
ClearArrayNode( Node *ctrl, Node *arymem, Node *word_cnt, Node *base )
: Node(ctrl,arymem,word_cnt,base) {
ClearArrayNode( Node *ctrl, Node *arymem, Node *word_cnt, Node *base, bool is_large)
: Node(ctrl,arymem,word_cnt,base), _is_large(is_large) {
init_class_id(Class_ClearArray);
}
virtual int Opcode() const;
@ -1026,6 +1028,7 @@ public:
virtual Node* Identity(PhaseGVN* phase);
virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
virtual uint match_edge(uint idx) const;
bool is_large() const { return _is_large; }
// Clear the given area of an object or array.
// The start offset must always be aligned mod BytesPerInt.

8
hotspot/src/share/vm/runtime/commandLineFlagConstraintsCompiler.cpp
View file

@ -354,6 +354,14 @@ Flag::Error TypeProfileLevelConstraintFunc(uintx value, bool verbose) {
return Flag::SUCCESS;
}
Flag::Error InitArrayShortSizeConstraintFunc(intx value, bool verbose) {
if (value % BytesPerLong != 0) {
return Flag::VIOLATES_CONSTRAINT;
} else {
return Flag::SUCCESS;
}
}
#ifdef COMPILER2
Flag::Error InteriorEntryAlignmentConstraintFunc(intx value, bool verbose) {
if (InteriorEntryAlignment > CodeEntryAlignment) {

2
hotspot/src/share/vm/runtime/commandLineFlagConstraintsCompiler.hpp
View file

@ -62,6 +62,8 @@ Flag::Error ArraycopySrcPrefetchDistanceConstraintFunc(uintx value, bool verbose
Flag::Error TypeProfileLevelConstraintFunc(uintx value, bool verbose);
Flag::Error InitArrayShortSizeConstraintFunc(intx value, bool verbose);
#ifdef COMPILER2
Flag::Error InteriorEntryAlignmentConstraintFunc(intx value, bool verbose);

7
hotspot/src/share/vm/runtime/globals.hpp
View file

@ -4162,6 +4162,13 @@ public:
"in the loaded class C. " \
"Check (3) is available only in debug builds.") \
\
develop_pd(intx, InitArrayShortSize, \
"Threshold small size (in bytes) for clearing arrays. " \
"Anything this size or smaller may get converted to discrete " \
"scalar stores.") \
range(0, max_intx) \
constraint(InitArrayShortSizeConstraintFunc, AfterErgo) \
\
diagnostic(bool, CompilerDirectivesIgnoreCompileCommands, false, \
"Disable backwards compatibility for compile commands.") \
\