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8305959: x86: Improve itable_stub
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Reviewed-by: simonis
Backport-of: 8cdd95e8a2a7814ab7983fb3f41e6fa5793d410f
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Dmitry Chuyko authored and Paul Hohensee committed Jul 9, 2024
1 parent e43402d commit 3069e3e
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Showing 5 changed files with 271 additions and 45 deletions.
119 changes: 119 additions & 0 deletions src/hotspot/cpu/x86/macroAssembler_x86.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3915,6 +3915,125 @@ void MacroAssembler::lookup_interface_method(Register recv_klass,
}
}

// Look up the method for a megamorphic invokeinterface call in a single pass over itable:
// - check recv_klass (actual object class) is a subtype of resolved_klass from CompiledICHolder
// - find a holder_klass (class that implements the method) vtable offset and get the method from vtable by index
// The target method is determined by <holder_klass, itable_index>.
// The receiver klass is in recv_klass.
// On success, the result will be in method_result, and execution falls through.
// On failure, execution transfers to the given label.
void MacroAssembler::lookup_interface_method_stub(Register recv_klass,
Register holder_klass,
Register resolved_klass,
Register method_result,
Register scan_temp,
Register temp_reg2,
Register receiver,
int itable_index,
Label& L_no_such_interface) {
assert_different_registers(recv_klass, method_result, holder_klass, resolved_klass, scan_temp, temp_reg2, receiver);
Register temp_itbl_klass = method_result;
Register temp_reg = (temp_reg2 == noreg ? recv_klass : temp_reg2); // reuse recv_klass register on 32-bit x86 impl

int vtable_base = in_bytes(Klass::vtable_start_offset());
int itentry_off = itableMethodEntry::method_offset_in_bytes();
int scan_step = itableOffsetEntry::size() * wordSize;
int vte_size = vtableEntry::size_in_bytes();
int ioffset = itableOffsetEntry::interface_offset_in_bytes();
int ooffset = itableOffsetEntry::offset_offset_in_bytes();
Address::ScaleFactor times_vte_scale = Address::times_ptr;
assert(vte_size == wordSize, "adjust times_vte_scale");

Label L_loop_scan_resolved_entry, L_resolved_found, L_holder_found;

// temp_itbl_klass = recv_klass.itable[0]
// scan_temp = &recv_klass.itable[0] + step
movl(scan_temp, Address(recv_klass, Klass::vtable_length_offset()));
movptr(temp_itbl_klass, Address(recv_klass, scan_temp, times_vte_scale, vtable_base + ioffset));
lea(scan_temp, Address(recv_klass, scan_temp, times_vte_scale, vtable_base + ioffset + scan_step));
xorptr(temp_reg, temp_reg);

// Initial checks:
// - if (holder_klass != resolved_klass), go to "scan for resolved"
// - if (itable[0] == 0), no such interface
// - if (itable[0] == holder_klass), shortcut to "holder found"
cmpptr(holder_klass, resolved_klass);
jccb(Assembler::notEqual, L_loop_scan_resolved_entry);
testptr(temp_itbl_klass, temp_itbl_klass);
jccb(Assembler::zero, L_no_such_interface);
cmpptr(holder_klass, temp_itbl_klass);
jccb(Assembler::equal, L_holder_found);

// Loop: Look for holder_klass record in itable
// do {
// tmp = itable[index];
// index += step;
// if (tmp == holder_klass) {
// goto L_holder_found; // Found!
// }
// } while (tmp != 0);
// goto L_no_such_interface // Not found.
Label L_scan_holder;
bind(L_scan_holder);
movptr(temp_itbl_klass, Address(scan_temp, 0));
addptr(scan_temp, scan_step);
cmpptr(holder_klass, temp_itbl_klass);
jccb(Assembler::equal, L_holder_found);
testptr(temp_itbl_klass, temp_itbl_klass);
jccb(Assembler::notZero, L_scan_holder);

jmpb(L_no_such_interface);

// Loop: Look for resolved_class record in itable
// do {
// tmp = itable[index];
// index += step;
// if (tmp == holder_klass) {
// // Also check if we have met a holder klass
// holder_tmp = itable[index-step-ioffset];
// }
// if (tmp == resolved_klass) {
// goto L_resolved_found; // Found!
// }
// } while (tmp != 0);
// goto L_no_such_interface // Not found.
//
Label L_loop_scan_resolved;
bind(L_loop_scan_resolved);
movptr(temp_itbl_klass, Address(scan_temp, 0));
addptr(scan_temp, scan_step);
bind(L_loop_scan_resolved_entry);
cmpptr(holder_klass, temp_itbl_klass);
cmovl(Assembler::equal, temp_reg, Address(scan_temp, ooffset - ioffset - scan_step));
cmpptr(resolved_klass, temp_itbl_klass);
jccb(Assembler::equal, L_resolved_found);
testptr(temp_itbl_klass, temp_itbl_klass);
jccb(Assembler::notZero, L_loop_scan_resolved);

jmpb(L_no_such_interface);

Label L_ready;

// See if we already have a holder klass. If not, go and scan for it.
bind(L_resolved_found);
testptr(temp_reg, temp_reg);
jccb(Assembler::zero, L_scan_holder);
jmpb(L_ready);

bind(L_holder_found);
movl(temp_reg, Address(scan_temp, ooffset - ioffset - scan_step));

// Finally, temp_reg contains holder_klass vtable offset
bind(L_ready);
assert(itableMethodEntry::size() * wordSize == wordSize, "adjust the scaling in the code below");
if (temp_reg2 == noreg) { // recv_klass register is clobbered for 32-bit x86 impl
load_klass(scan_temp, receiver, noreg);
movptr(method_result, Address(scan_temp, temp_reg, Address::times_1, itable_index * wordSize + itentry_off));
} else {
movptr(method_result, Address(recv_klass, temp_reg, Address::times_1, itable_index * wordSize + itentry_off));
}
}


// virtual method calling
void MacroAssembler::lookup_virtual_method(Register recv_klass,
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10 changes: 10 additions & 0 deletions src/hotspot/cpu/x86/macroAssembler_x86.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -556,6 +556,16 @@ class MacroAssembler: public Assembler {
Label& no_such_interface,
bool return_method = true);

void lookup_interface_method_stub(Register recv_klass,
Register holder_klass,
Register resolved_klass,
Register method_result,
Register scan_temp,
Register temp_reg2,
Register receiver,
int itable_index,
Label& L_no_such_interface);

// virtual method calling
void lookup_virtual_method(Register recv_klass,
RegisterOrConstant vtable_index,
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43 changes: 19 additions & 24 deletions src/hotspot/cpu/x86/vtableStubs_x86_32.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -179,14 +179,16 @@ VtableStub* VtableStubs::create_itable_stub(int itable_index) {
// rax: CompiledICHolder
// rcx: Receiver

// Most registers are in use; we'll use rax, rbx, rsi, rdi
// Most registers are in use; we'll use rax, rbx, rcx, rdx, rsi, rdi
// (If we need to make rsi, rdi callee-save, do a push/pop here.)
const Register recv_klass_reg = rsi;
const Register holder_klass_reg = rax; // declaring interface klass (DECC)
const Register resolved_klass_reg = rbx; // resolved interface klass (REFC)
const Register temp_reg = rdi;
const Register resolved_klass_reg = rdi; // resolved interface klass (REFC)
const Register temp_reg = rdx;
const Register method = rbx;
const Register icholder_reg = rax;
const Register receiver = rcx;

const Register icholder_reg = rax;
__ movptr(resolved_klass_reg, Address(icholder_reg, CompiledICHolder::holder_klass_offset()));
__ movptr(holder_klass_reg, Address(icholder_reg, CompiledICHolder::holder_metadata_offset()));

Expand All @@ -198,35 +200,26 @@ VtableStub* VtableStubs::create_itable_stub(int itable_index) {
__ load_klass(recv_klass_reg, rcx, noreg);

start_pc = __ pc();
__ push(rdx); // temp_reg

// Receiver subtype check against REFC.
// Destroys recv_klass_reg value.
__ lookup_interface_method(// inputs: rec. class, interface
recv_klass_reg, resolved_klass_reg, noreg,
// outputs: scan temp. reg1, scan temp. reg2
recv_klass_reg, temp_reg,
L_no_such_interface,
/*return_method=*/false);

const ptrdiff_t typecheckSize = __ pc() - start_pc;
start_pc = __ pc();

// Get selected method from declaring class and itable index
const Register method = rbx;
__ load_klass(recv_klass_reg, rcx, noreg); // restore recv_klass_reg
__ lookup_interface_method(// inputs: rec. class, interface, itable index
recv_klass_reg, holder_klass_reg, itable_index,
// outputs: method, scan temp. reg
method, temp_reg,
L_no_such_interface);

__ lookup_interface_method_stub(recv_klass_reg, // input
holder_klass_reg, // input
resolved_klass_reg, // input
method, // output
temp_reg,
noreg,
receiver, // input (x86_32 only: to restore recv_klass value)
itable_index,
L_no_such_interface);
const ptrdiff_t lookupSize = __ pc() - start_pc;

// We expect we need index_dependent_slop extra bytes. Reason:
// The emitted code in lookup_interface_method changes when itable_index exceeds 31.
// For windows, a narrow estimate was found to be 104. Other OSes not tested.
const ptrdiff_t estimate = 104;
const ptrdiff_t codesize = typecheckSize + lookupSize + index_dependent_slop;
const ptrdiff_t codesize = lookupSize + index_dependent_slop;
slop_delta = (int)(estimate - codesize);
slop_bytes += slop_delta;
assert(slop_delta >= 0, "itable #%d: Code size estimate (%d) for lookup_interface_method too small, required: %d", itable_index, (int)estimate, (int)codesize);
Expand All @@ -246,6 +239,7 @@ VtableStub* VtableStubs::create_itable_stub(int itable_index) {
}
#endif // ASSERT

__ pop(rdx);
address ame_addr = __ pc();
__ jmp(Address(method, Method::from_compiled_offset()));

Expand All @@ -255,6 +249,7 @@ VtableStub* VtableStubs::create_itable_stub(int itable_index) {
// We force resolving of the call site by jumping to the "handle
// wrong method" stub, and so let the interpreter runtime do all the
// dirty work.
__ pop(rdx);
__ jump(RuntimeAddress(SharedRuntime::get_handle_wrong_method_stub()));

masm->flush();
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35 changes: 14 additions & 21 deletions src/hotspot/cpu/x86/vtableStubs_x86_64.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -176,10 +176,12 @@ VtableStub* VtableStubs::create_itable_stub(int itable_index) {
// (various calling sequences use r[cd]x, r[sd]i, r[89]; stay away from them)
const Register recv_klass_reg = r10;
const Register holder_klass_reg = rax; // declaring interface klass (DECC)
const Register resolved_klass_reg = rbx; // resolved interface klass (REFC)
const Register resolved_klass_reg = r14; // resolved interface klass (REFC)
const Register temp_reg = r11;
const Register temp_reg2 = r13;
const Register method = rbx;
const Register icholder_reg = rax;

const Register icholder_reg = rax;
__ movptr(resolved_klass_reg, Address(icholder_reg, CompiledICHolder::holder_klass_offset()));
__ movptr(holder_klass_reg, Address(icholder_reg, CompiledICHolder::holder_metadata_offset()));

Expand All @@ -193,33 +195,24 @@ VtableStub* VtableStubs::create_itable_stub(int itable_index) {
start_pc = __ pc();

// Receiver subtype check against REFC.
// Destroys recv_klass_reg value.
__ lookup_interface_method(// inputs: rec. class, interface
recv_klass_reg, resolved_klass_reg, noreg,
// outputs: scan temp. reg1, scan temp. reg2
recv_klass_reg, temp_reg,
L_no_such_interface,
/*return_method=*/false);

const ptrdiff_t typecheckSize = __ pc() - start_pc;
start_pc = __ pc();

// Get selected method from declaring class and itable index
const Register method = rbx;
__ load_klass(recv_klass_reg, j_rarg0, temp_reg); // restore recv_klass_reg
__ lookup_interface_method(// inputs: rec. class, interface, itable index
recv_klass_reg, holder_klass_reg, itable_index,
// outputs: method, scan temp. reg
method, temp_reg,
L_no_such_interface);
__ lookup_interface_method_stub(recv_klass_reg, // input
holder_klass_reg, // input
resolved_klass_reg, // input
method, // output
temp_reg,
temp_reg2,
noreg,
itable_index,
L_no_such_interface);

const ptrdiff_t lookupSize = __ pc() - start_pc;

// We expect we need index_dependent_slop extra bytes. Reason:
// The emitted code in lookup_interface_method changes when itable_index exceeds 15.
// For linux, a very narrow estimate would be 112, but Solaris requires some more space (130).
const ptrdiff_t estimate = 136;
const ptrdiff_t codesize = typecheckSize + lookupSize + index_dependent_slop;
const ptrdiff_t codesize = lookupSize + index_dependent_slop;
slop_delta = (int)(estimate - codesize);
slop_bytes += slop_delta;
assert(slop_delta >= 0, "itable #%d: Code size estimate (%d) for lookup_interface_method too small, required: %d", itable_index, (int)estimate, (int)codesize);
Expand Down
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