/* * Copyright (c) 1999, 2021, Oracle and/or its affiliates. All rights reserved. * Copyright (c) 2012, 2021 SAP SE. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. *
*/
void ImplicitNullCheckStub::emit_code(LIR_Assembler* ce) {
address a; if (_info->deoptimize_on_exception()) { // Deoptimize, do not throw the exception, because it is probably wrong to do it here.
a = Runtime1::entry_for(Runtime1::predicate_failed_trap_id);
} else {
a = Runtime1::entry_for(Runtime1::throw_null_pointer_exception_id);
}
// Implementation of patching: // - Copy the code at given offset to an inlined buffer (first the bytes, then the number of bytes). // - Replace original code with a call to the stub. // At Runtime: // - call to stub, jump to runtime // - in runtime: preserve all registers (especially objects, i.e., source and destination object) // - in runtime: after initializing class, restore original code, reexecute instruction
int PatchingStub::_patch_info_offset = -(5 * BytesPerInstWord);
void PatchingStub::align_patch_site(MacroAssembler* ) { // Patch sites on ppc are always properly aligned.
}
#ifdef ASSERT inlinevoid compare_with_patch_site(address template_start, address pc_start, int bytes_to_copy) {
address start = template_start; for (int i = 0; i < bytes_to_copy; i++) {
address ptr = (address)(pc_start + i); int a_byte = (*ptr) & 0xFF;
assert(a_byte == *start++, "should be the same code");
}
} #endif
void PatchingStub::emit_code(LIR_Assembler* ce) { // copy original code here
assert(NativeGeneralJump::instruction_size <= _bytes_to_copy && _bytes_to_copy <= 0xFF, "not enough room for call, need %d", _bytes_to_copy);
assert((_bytes_to_copy & 0x3) == 0, "must copy a multiple of four bytes");
Label call_patch;
int being_initialized_entry = __ offset();
if (_id == load_klass_id) { // Produce a copy of the load klass instruction for use by the being initialized case.
AddressLiteral addrlit((address)NULL, metadata_Relocation::spec(_index));
__ load_const(_obj, addrlit, R0);
DEBUG_ONLY( compare_with_patch_site(__ code_section()->start() + being_initialized_entry, _pc_start, _bytes_to_copy); )
} elseif (_id == load_mirror_id || _id == load_appendix_id) { // Produce a copy of the load mirror instruction for use by the being initialized case.
AddressLiteral addrlit((address)NULL, oop_Relocation::spec(_index));
__ load_const(_obj, addrlit, R0);
DEBUG_ONLY( compare_with_patch_site(__ code_section()->start() + being_initialized_entry, _pc_start, _bytes_to_copy); )
} else { // Make a copy of the code which is going to be patched. for (int i = 0; i < _bytes_to_copy; i++) {
address ptr = (address)(_pc_start + i); int a_byte = (*ptr) & 0xFF;
__ emit_int8 (a_byte);
}
}
address end_of_patch = __ pc(); int bytes_to_skip = 0; if (_id == load_mirror_id) { int offset = __ offset();
__ block_comment(" being_initialized check");
// Static field accesses have special semantics while the class // initializer is being run so we emit a test which can be used to // check that this code is being executed by the initializing // thread.
assert(_obj != noreg, "must be a valid register");
assert(_index >= 0, "must have oop index");
__ mr(R0, _obj); // spill
__ ld(_obj, java_lang_Class::klass_offset(), _obj);
__ ld(_obj, in_bytes(InstanceKlass::init_thread_offset()), _obj);
__ cmpd(CCR0, _obj, R16_thread);
__ mr(_obj, R0); // restore
__ bne(CCR0, call_patch);
// Load_klass patches may execute the patched code before it's // copied back into place so we need to jump back into the main // code of the nmethod to continue execution.
__ b(_patch_site_continuation);
// Make sure this extra code gets skipped.
bytes_to_skip += __ offset() - offset;
}
// Now emit the patch record telling the runtime how to find the // pieces of the patch. We only need 3 bytes but it has to be // aligned as an instruction so emit 4 bytes. int sizeof_patch_record = 4;
bytes_to_skip += sizeof_patch_record;
// Emit the offsets needed to find the code to patch. int being_initialized_entry_offset = __ offset() - being_initialized_entry + sizeof_patch_record;
// Emit the patch record. We need to emit a full word, so emit an extra empty byte.
__ emit_int8(0);
__ emit_int8(being_initialized_entry_offset);
__ emit_int8(bytes_to_skip);
__ emit_int8(_bytes_to_copy);
address patch_info_pc = __ pc();
assert(patch_info_pc - end_of_patch == bytes_to_skip, "incorrect patch info");
bool success = ce->emit_trampoline_stub_for_call(SharedRuntime::get_resolve_static_call_stub()); if (!success) { return; }
__ relocate(relocInfo::static_call_type); // Note: At this point we do not have the address of the trampoline // stub, and the entry point might be too far away for bl, so __ pc() // serves as dummy and the bl will be patched later.
__ code()->set_insts_mark();
__ bl(__ pc());
ce->add_call_info_here(info());
ce->verify_oop_map(info());
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