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#include "gc/shenandoah/shenandoahHeap.inline.hpp"
#include "gc/shenandoah/shenandoahHeapRegion.hpp"
#include "gc/shenandoah/shenandoahRuntime.hpp"
#include "gc/shenandoah/shenandoahThreadLocalData.hpp"
#include "interpreter/interpreter.hpp"
+ #include "nativeInst_x86.hpp"
#include "runtime/javaThread.hpp"
#include "runtime/sharedRuntime.hpp"
#include "utilities/macros.hpp"
#ifdef COMPILER1
#include "c1/c1_LIRAssembler.hpp"
}
void ShenandoahBarrierStubC2::enter_if_gc_state(MacroAssembler& masm, const char test_state, Register tmp) {
Assembler::InlineSkippedInstructionsCounter skip_counter(&masm);
+ // Emit the unconditional branch in the first version of the method.
+ // Let the rest of runtime figure out how to manage it.
+ __ relocate(barrier_Relocation::spec(), ShenandoahThreadLocalData::gc_state_to_fast_array_index(test_state));
+ __ jmp(*entry(), /* maybe_short = */ false);
+
+ #ifdef ASSERT
Address gc_state_fast(r15_thread, in_bytes(ShenandoahThreadLocalData::gc_state_fast_array_offset(test_state)));
__ cmpb(gc_state_fast, 0);
- __ jcc(Assembler::notEqual, *entry());
+ __ jccb(Assembler::zero, *continuation());
+ __ hlt(); // Correctness bug: barrier is NOP-ed, but heap is NOT IDLE
+ #endif
+ // TODO: When barriers are consistently turned off at the end of the cycle, assert that barrier is NOP-ed.
+
__ bind(*continuation());
}
+ address ShenandoahBarrierSetAssembler::parse_stub_address(address pc) {
+ NativeInstruction* ni = nativeInstruction_at(pc);
+ assert(ni->is_jump(), "Initial code version: GC barrier fastpath must be a jump");
+ NativeJump* jmp = nativeJump_at(pc);
+ return jmp->jump_destination();
+ }
+
+ void insert_5_byte_nop(address pc) {
+ *(pc + 0) = 0x0F;
+ *(pc + 1) = 0x1F;
+ *(pc + 2) = 0x44;
+ *(pc + 3) = 0x00;
+ *(pc + 4) = 0x00;
+ ICache::invalidate_range(pc, 5);
+ }
+
+ bool is_5_byte_nop(address pc) {
+ if (*(pc + 0) != 0x0F) return false;
+ if (*(pc + 1) != 0x1F) return false;
+ if (*(pc + 2) != 0x44) return false;
+ if (*(pc + 3) != 0x00) return false;
+ if (*(pc + 4) != 0x00) return false;
+ return true;
+ }
+
+ void check_at(bool cond, address pc, const char* msg) {
+ assert(cond, "%s: at PC " PTR_FORMAT ": %02x%02x%02x%02x%02x",
+ msg, p2i(pc), *(pc + 0), *(pc + 1), *(pc + 2), *(pc + 3), *(pc + 4));
+ }
+
+ bool ShenandoahBarrierSetAssembler::is_active(address pc) {
+ NativeInstruction* ni = nativeInstruction_at(pc);
+ return ni->is_jump();
+ }
+
+ void ShenandoahBarrierSetAssembler::patch_branch_to_nop(address pc) {
+ NativeInstruction* ni = nativeInstruction_at(pc);
+ if (ni->is_jump()) {
+ insert_5_byte_nop(pc);
+ } else {
+ check_at(is_5_byte_nop(pc), pc, "Should already be nop");
+ }
+ }
+
+ void ShenandoahBarrierSetAssembler::patch_nop_to_branch(address pc, address stub_addr) {
+ NativeInstruction* ni = nativeInstruction_at(pc);
+ if (is_5_byte_nop(pc)) {
+ NativeJump::insert(pc, stub_addr);
+ } else {
+ check_at(ni->is_jump(), pc, "Should already be jump");
+ check_at(nativeJump_at(pc)->jump_destination() == stub_addr, pc, "Jump should be to the same address");
+ }
+ }
+
void ShenandoahBarrierStubC2::emit_code(MacroAssembler& masm) {
Assembler::InlineSkippedInstructionsCounter skip_counter(&masm);
assert(_needs_keep_alive_barrier || _needs_load_ref_barrier, "Why are you here?");
// On x86, there is a significant penalty with unaligned branch target, for example
__ movq(_obj, _addr);
}
}
// If the object is null, there is no point in applying barriers.
- maybe_far_jump_if_zero(masm, _obj);
+ maybe_far_jump_if_zero(masm, _obj, continuation());
// We need to make sure that loads done by callers survive across slow-path calls.
// For self-loads, we need to care about the case when both KA and LRB are enabled (rare).
bool needs_both_barriers = _needs_keep_alive_barrier && _needs_load_ref_barrier;
if (!_do_load || needs_both_barriers) {
Address index(r15_thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_index_offset()));
Address buffer(r15_thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset()));
Label L_through, L_pop_and_slow;
- // If another barrier is enabled as well, do a runtime check for a specific barrier.
- if (_needs_load_ref_barrier) {
- assert(L_done == nullptr, "L_done is always null when _needs_load_ref_barrier is true");
- __ cmpb(gc_state_fast, 0);
+ // Hotpatched GC checks are racy: we can turn off GC state before we patch the barriers.
+ // Therefore, alas we need a separate check here. TODO: Figure this out.
+ __ cmpb(gc_state_fast, 0);
+ if (L_done != nullptr) {
+ __ jcc(Assembler::equal, *L_done);
+ } else {
__ jcc(Assembler::equal, L_through);
}
// Need temp to work, allocate one now.
bool tmp_live;
}
void ShenandoahBarrierStubC2::lrb(MacroAssembler& masm) {
Label L_pop_and_slow, L_slow;
- // If another barrier is enabled as well, do a runtime check for a specific barrier.
- if (_needs_keep_alive_barrier) {
- char state_to_check = ShenandoahHeap::HAS_FORWARDED | (_needs_load_ref_weak_barrier ? ShenandoahHeap::WEAK_ROOTS : 0);
- Address gc_state_fast(r15_thread, in_bytes(ShenandoahThreadLocalData::gc_state_fast_array_offset(state_to_check)));
- __ cmpb(gc_state_fast, 0);
- __ jcc(Assembler::equal, *continuation());
- }
+ // Hotpatched GC checks are racy: we can turn off GC state before we patch the barriers.
+ // Therefore, alas we need a separate check here. TODO: Figure this out.
+ char state_to_check = ShenandoahHeap::HAS_FORWARDED | (_needs_load_ref_weak_barrier ? ShenandoahHeap::WEAK_ROOTS : 0);
+ Address gc_state_fast(r15_thread, in_bytes(ShenandoahThreadLocalData::gc_state_fast_array_offset(state_to_check)));
+ __ cmpb(gc_state_fast, 0);
+ __ jcc(Assembler::equal, *continuation());
// If weak references are being processed, weak/phantom loads need to go slow,
// regardless of their cset status.
if (_needs_load_ref_weak_barrier) {
Address gc_state_fast(r15_thread, in_bytes(ShenandoahThreadLocalData::gc_state_fast_array_offset(ShenandoahHeap::WEAK_ROOTS)));
void ShenandoahBarrierStubC2::post_init() {
// Do nothing.
}
- void ShenandoahBarrierStubC2::maybe_far_jump_if_zero(MacroAssembler& masm, Register reg) {
+ void ShenandoahBarrierStubC2::maybe_far_jump_if_zero(MacroAssembler& masm, Register reg, Label* L_target) {
if (_narrow) {
__ testl(reg, reg);
} else {
__ testq(reg, reg);
}
- __ jcc(Assembler::zero, *continuation());
+ __ jcc(Assembler::zero, *L_target);
}
#endif // COMPILER2
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