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8329433: Reduce nmethod header size #18768

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a0c46b8
8329433: Reduce nmethod header size
vnkozlov Apr 12, 2024
488f1b9
Moved some fields initialization into init_defaults()
vnkozlov Apr 15, 2024
13744e7
Union fields which usages do not overlap
vnkozlov Apr 15, 2024
6cb22e8
Use 16-bits types for header_size and frame_complete_offset arguments
vnkozlov Apr 16, 2024
8405a23
Address comments. Used checked_cast.
vnkozlov Apr 16, 2024
71ade0f
Shuffle fields initialization
vnkozlov Apr 17, 2024
6a164b1
remove trailing space
vnkozlov Apr 17, 2024
adc1759
Merge master
vnkozlov Apr 17, 2024
5f5f30d
Address comment
vnkozlov Apr 17, 2024
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2 changes: 0 additions & 2 deletions src/hotspot/share/code/codeBlob.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -112,9 +112,7 @@ CodeBlob::CodeBlob(const char* name, CodeBlobKind kind, int size, uint16_t heade
_code_offset(_content_offset),
_data_offset(size),
_frame_size(0),

S390_ONLY(_ctable_offset(0) COMMA)

_header_size(header_size),
_frame_complete_offset(CodeOffsets::frame_never_safe),
_kind(kind),
Expand Down
155 changes: 76 additions & 79 deletions src/hotspot/share/code/nmethod.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -996,31 +996,6 @@ const char* nmethod::compiler_name() const {
return compilertype2name(_compiler_type);
}

// Fill in default values for various flag fields
void nmethod::init_defaults() {
// avoid uninitialized fields, even for short time periods
_exception_cache = nullptr;
_gc_data = nullptr;
_oops_do_mark_link = nullptr;
_compiled_ic_data = nullptr;

#if INCLUDE_RTM_OPT
_rtm_state = NoRTM;
#endif
_is_unloading_state = 0;
_state = not_installed;

_has_unsafe_access = 0;
_has_method_handle_invokes = 0;
_has_wide_vectors = 0;
_has_monitors = 0;
_has_flushed_dependencies = 0;
_is_unlinked = 0;
_load_reported = 0; // jvmti state

_deoptimization_status = not_marked;
}

#ifdef ASSERT
class CheckForOopsClosure : public OopClosure {
bool _found_oop = false;
Expand Down Expand Up @@ -1195,6 +1170,53 @@ nmethod* nmethod::new_nmethod(const methodHandle& method,
return nm;
}

// Fill in default values for various fields
void nmethod::init_defaults(CodeBuffer *code_buffer, CodeOffsets* offsets) {
// avoid uninitialized fields, even for short time periods
_exception_cache = nullptr;
_gc_data = nullptr;
_oops_do_mark_link = nullptr;
_compiled_ic_data = nullptr;

#if INCLUDE_RTM_OPT
_rtm_state = NoRTM;
#endif
_is_unloading_state = 0;
_state = not_installed;

_has_unsafe_access = 0;
_has_method_handle_invokes = 0;
_has_wide_vectors = 0;
_has_monitors = 0;
_has_flushed_dependencies = 0;
_is_unlinked = 0;
_load_reported = 0; // jvmti state

_deoptimization_status = not_marked;

// SECT_CONSTS is first in code buffer so the offset should be 0.
int consts_offset = code_buffer->total_offset_of(code_buffer->consts());
assert(consts_offset == 0, "const_offset: %d", consts_offset);

_entry_offset = checked_cast<uint16_t>(offsets->value(CodeOffsets::Entry));
_verified_entry_offset = checked_cast<uint16_t>(offsets->value(CodeOffsets::Verified_Entry));
_stub_offset = content_offset() + code_buffer->total_offset_of(code_buffer->stubs());

_skipped_instructions_size = checked_cast<uint16_t>(code_buffer->total_skipped_instructions_size());
}

// Post initialization
void nmethod::post_init() {
clear_unloading_state();

finalize_relocations();

Universe::heap()->register_nmethod(this);
debug_only(Universe::heap()->verify_nmethod(this));

CodeCache::commit(this);
}

// For native wrappers
nmethod::nmethod(
Method* method,
Expand All @@ -1210,6 +1232,7 @@ nmethod::nmethod(
: CodeBlob("native nmethod", CodeBlobKind::Nmethod, code_buffer, nmethod_size, sizeof(nmethod),
offsets->value(CodeOffsets::Frame_Complete), frame_size, oop_maps, false),
_deoptimization_generation(0),
_gc_epoch(CodeCache::gc_epoch()),
_method(method),
_native_receiver_sp_offset(basic_lock_owner_sp_offset),
_native_basic_lock_sp_offset(basic_lock_sp_offset)
Expand All @@ -1218,25 +1241,27 @@ nmethod::nmethod(
debug_only(NoSafepointVerifier nsv;)
assert_locked_or_safepoint(CodeCache_lock);

init_defaults();
_comp_level = CompLevel_none;
init_defaults(code_buffer, offsets);

_osr_entry_point = nullptr;
_entry_bci = InvocationEntryBci;
// We have no exception handler or deopt handler make the
// values something that will never match a pc like the nmethod vtable entry
_exception_offset = 0;
_compile_id = compile_id;
_comp_level = CompLevel_none;
_compiler_type = type;
_orig_pc_offset = 0;

if (offsets->value(CodeOffsets::Exceptions) != -1) {
// Continuation enter intrinsic
_exception_offset = code_offset() + offsets->value(CodeOffsets::Exceptions);
} else {
_exception_offset = 0;
}
// Native wrappers do not have deopt handlers. Make the values
// something that will never match a pc like the nmethod vtable entry
_deopt_handler_offset = 0;
_deopt_mh_handler_offset = 0;
_unwind_handler_offset = 0;
_gc_epoch = CodeCache::gc_epoch();

// SECT_CONSTS is first in code buffer so the offset should be 0.
int consts_offset = code_buffer->total_offset_of(code_buffer->consts());
assert(consts_offset == 0, "const_offset: %d", consts_offset);

_skipped_instructions_size = checked_cast<uint16_t>(code_buffer->total_skipped_instructions_size());

_stub_offset = content_offset() + code_buffer->total_offset_of(code_buffer->stubs());
#ifdef ASSERT
int oops_size = align_up(code_buffer->total_oop_size(), oopSize);
int metadata_size = align_up(code_buffer->total_metadata_size(), wordSize);
Expand All @@ -1258,27 +1283,12 @@ nmethod::nmethod(
#endif
assert((data_offset() + data_end_offset) <= nmethod_size, "wrong nmethod's size: %d < %d", nmethod_size, (data_offset() + data_end_offset));

_compile_id = compile_id;
_compiler_type = type;
_entry_offset = checked_cast<uint16_t>(offsets->value(CodeOffsets::Entry));
_verified_entry_offset = checked_cast<uint16_t>(offsets->value(CodeOffsets::Verified_Entry));
_osr_entry_point = nullptr;
_pc_desc_container.reset_to(nullptr);

if (offsets->value(CodeOffsets::Exceptions) != -1) {
_exception_offset = code_offset() + offsets->value(CodeOffsets::Exceptions);
}
code_buffer->copy_code_and_locs_to(this);
code_buffer->copy_values_to(this);

clear_unloading_state();

finalize_relocations();

Universe::heap()->register_nmethod(this);
debug_only(Universe::heap()->verify_nmethod(this));

CodeCache::commit(this);
post_init();
}

if (PrintNativeNMethods || PrintDebugInfo || PrintRelocations || PrintDependencies) {
Expand Down Expand Up @@ -1336,6 +1346,7 @@ void* nmethod::operator new(size_t size, int nmethod_size, bool allow_NonNMethod
return CodeCache::allocate(nmethod_size, CodeBlobType::NonNMethod);
}

// For normal JIT compiled code
nmethod::nmethod(
Method* method,
CompilerType type,
Expand All @@ -1362,6 +1373,7 @@ nmethod::nmethod(
: CodeBlob("nmethod", CodeBlobKind::Nmethod, code_buffer, nmethod_size, sizeof(nmethod),
offsets->value(CodeOffsets::Frame_Complete), frame_size, oop_maps, false),
_deoptimization_generation(0),
_gc_epoch(CodeCache::gc_epoch()),
_method(method),
_osr_link(nullptr)
{
Expand All @@ -1370,21 +1382,15 @@ nmethod::nmethod(
debug_only(NoSafepointVerifier nsv;)
assert_locked_or_safepoint(CodeCache_lock);

init_defaults();
_entry_bci = entry_bci;
_compile_id = compile_id;
_compiler_type = type;
_comp_level = comp_level;
_orig_pc_offset = orig_pc_offset;
_gc_epoch = CodeCache::gc_epoch();

// SECT_CONSTS is first in code buffer so the offset should be 0.
int consts_offset = code_buffer->total_offset_of(code_buffer->consts());
assert(consts_offset == 0, "const_offset: %d", consts_offset);
init_defaults(code_buffer, offsets);

_skipped_instructions_size = checked_cast<uint16_t>(code_buffer->total_skipped_instructions_size());
_osr_entry_point = code_begin() + offsets->value(CodeOffsets::OSR_Entry);
_entry_bci = entry_bci;
_compile_id = compile_id;
_comp_level = comp_level;
_compiler_type = type;
_orig_pc_offset = orig_pc_offset;

_stub_offset = content_offset() + code_buffer->total_offset_of(code_buffer->stubs());
set_ctable_begin(header_begin() + content_offset());

#if INCLUDE_JVMCI
Expand Down Expand Up @@ -1448,18 +1454,14 @@ nmethod::nmethod(
#endif
assert((data_offset() + data_end_offset) <= nmethod_size, "wrong nmethod's size: %d < %d", nmethod_size, (data_offset() + data_end_offset));

_entry_offset = checked_cast<uint16_t>(offsets->value(CodeOffsets::Entry));
_verified_entry_offset = checked_cast<uint16_t>(offsets->value(CodeOffsets::Verified_Entry));
_osr_entry_point = code_begin() + offsets->value(CodeOffsets::OSR_Entry);

// after _scopes_pcs_offset is set
_pc_desc_container.reset_to(scopes_pcs_begin());

code_buffer->copy_code_and_locs_to(this);
// Copy contents of ScopeDescRecorder to nmethod
code_buffer->copy_values_to(this);
debug_info->copy_to(this);
dependencies->copy_to(this);
clear_unloading_state();

#if INCLUDE_JVMCI
if (compiler->is_jvmci()) {
Expand All @@ -1468,13 +1470,6 @@ nmethod::nmethod(
}
#endif

finalize_relocations();

Universe::heap()->register_nmethod(this);
debug_only(Universe::heap()->verify_nmethod(this));

CodeCache::commit(this);

// Copy contents of ExceptionHandlerTable to nmethod
handler_table->copy_to(this);
nul_chk_table->copy_to(this);
Expand All @@ -1486,6 +1481,8 @@ nmethod::nmethod(
}
#endif

post_init();

// we use the information of entry points to find out if a method is
// static or non static
assert(compiler->is_c2() || compiler->is_jvmci() ||
Expand Down
11 changes: 7 additions & 4 deletions src/hotspot/share/code/nmethod.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -294,6 +294,12 @@ class nmethod : public CodeBlob {
return Atomic::load(&_deoptimization_status);
}

// Initialize fields to their default values
void init_defaults(CodeBuffer *code_buffer, CodeOffsets* offsets);

// Post initialization
void post_init();

// For native wrappers
nmethod(Method* method,
CompilerType type,
Expand All @@ -306,7 +312,7 @@ class nmethod : public CodeBlob {
ByteSize basic_lock_sp_offset, /* synchronized natives only */
OopMapSet* oop_maps);

// Creation support
// For normal JIT compiled code
nmethod(Method* method,
CompilerType type,
int nmethod_size,
Expand Down Expand Up @@ -350,9 +356,6 @@ class nmethod : public CodeBlob {
// Inform external interfaces that a compiled method has been unloaded
void post_compiled_method_unload();

// Initialize fields to their default values
void init_defaults();

PcDesc* find_pc_desc(address pc, bool approximate) {
return _pc_desc_container.find_pc_desc(pc, approximate, PcDescSearch(code_begin(), scopes_pcs_begin(), scopes_pcs_end()));
}
Expand Down