8241613: Suspicious calls to MacroAssembler::null_check(Register, offset)

Reviewed-by: dholmes, coleenp, fparain, adinn

src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp

@@ -4323,11 +4323,6 @@ void MacroAssembler::load_klass(Register dst, Register src) {
   }
 }
 
-void MacroAssembler::load_klass_check_null(Register dst, Register src) {
-  null_check(src, oopDesc::klass_offset_in_bytes());
-  load_klass(dst, src);
-}
-
 // ((OopHandle)result).resolve();
 void MacroAssembler::resolve_oop_handle(Register result, Register tmp1, Register tmp2) {
   // OopHandle::resolve is an indirection.

src/hotspot/cpu/aarch64/macroAssembler_aarch64.hpp

@@ -850,7 +850,6 @@ public:
 
   // oop manipulations
   void load_klass(Register dst, Register src);
-  void load_klass_check_null(Register dst, Register src);
   void store_klass(Register dst, Register src);
   void cmp_klass(Register oop, Register trial_klass, Register tmp);
 

src/hotspot/cpu/aarch64/methodHandles_aarch64.cpp

@@ -322,7 +322,7 @@ void MethodHandles::generate_method_handle_dispatch(MacroAssembler* _masm,
         __ null_check(receiver_reg);
       } else {
         // load receiver klass itself
-        __ load_klass_check_null(temp1_recv_klass, receiver_reg);
+        __ load_klass(temp1_recv_klass, receiver_reg);
         __ verify_klass_ptr(temp1_recv_klass);
       }
       BLOCK_COMMENT("check_receiver {");

src/hotspot/cpu/aarch64/templateTable_aarch64.cpp

@@ -730,8 +730,6 @@ void TemplateTable::wide_aload()
 void TemplateTable::index_check(Register array, Register index)
 {
   // destroys r1, rscratch1
-  // check array
-  __ null_check(array, arrayOopDesc::length_offset_in_bytes());
   // sign extend index for use by indexed load
   // __ movl2ptr(index, index);
   // check index
@@ -3305,7 +3303,7 @@ void TemplateTable::invokevirtual_helper(Register index,
   __ bind(notFinal);
 
   // get receiver klass
-  __ load_klass_check_null(r0, recv);
+  __ load_klass(r0, recv);
 
   // profile this call
   __ profile_virtual_call(r0, rlocals, r3);
@@ -3393,8 +3391,8 @@ void TemplateTable::invokeinterface(int byte_no) {
   Label notVFinal;
   __ tbz(r3, ConstantPoolCacheEntry::is_vfinal_shift, notVFinal);
 
-  // Get receiver klass into r3 - also a null check
-  __ load_klass_check_null(r3, r2);
+  // Get receiver klass into r3
+  __ load_klass(r3, r2);
 
   Label subtype;
   __ check_klass_subtype(r3, r0, r4, subtype);
@@ -3408,9 +3406,9 @@ void TemplateTable::invokeinterface(int byte_no) {
 
   __ bind(notVFinal);
 
-  // Get receiver klass into r3 - also a null check
+  // Get receiver klass into r3
   __ restore_locals();
-  __ load_klass_check_null(r3, r2);
+  __ load_klass(r3, r2);
 
   Label no_such_method;
 
@@ -3650,7 +3648,6 @@ void TemplateTable::anewarray() {
 
 void TemplateTable::arraylength() {
   transition(atos, itos);
-  __ null_check(r0, arrayOopDesc::length_offset_in_bytes());
   __ ldrw(r0, Address(r0, arrayOopDesc::length_offset_in_bytes()));
 }
 

src/hotspot/cpu/arm/macroAssembler_arm.cpp

@@ -1653,11 +1653,6 @@ void MacroAssembler::load_klass(Register dst_klass, Register src_oop, AsmConditi
   ldr(dst_klass, Address(src_oop, oopDesc::klass_offset_in_bytes()), cond);
 }
 
-void MacroAssembler::load_klass_check_null(Register dst_klass, Register src_oop, Register tmp, AsmCondition cond) {
-  null_check(src_oop, tmp, oopDesc::klass_offset_in_bytes());
-  load_klass(dst_klass, src_oop, cond);
-}
-
 // Blows src_klass.
 void MacroAssembler::store_klass(Register src_klass, Register dst_oop) {
   str(src_klass, Address(dst_oop, oopDesc::klass_offset_in_bytes()));

src/hotspot/cpu/arm/macroAssembler_arm.hpp

@@ -853,7 +853,6 @@ public:
     // klass oop manipulations if compressed
 
   void load_klass(Register dst_klass, Register src_oop, AsmCondition cond = al);
-  void load_klass_check_null(Register dst_klass, Register src_oop, Register tmp, AsmCondition cond = al);
 
   void store_klass(Register src_klass, Register dst_oop);
 

src/hotspot/cpu/arm/methodHandles_arm.cpp

@@ -331,7 +331,7 @@ void MethodHandles::generate_method_handle_dispatch(MacroAssembler* _masm,
         __ null_check(receiver_reg, temp3);
       } else {
         // load receiver klass itself
-        __ load_klass_check_null(temp1_recv_klass, receiver_reg, temp3);
+        __ load_klass(temp1_recv_klass, receiver_reg);
         __ verify_klass_ptr(temp1_recv_klass);
       }
       BLOCK_COMMENT("check_receiver {");

src/hotspot/cpu/arm/templateTable_arm.cpp

@@ -812,8 +812,6 @@ void TemplateTable::index_check(Register array, Register index) {
 
 void TemplateTable::index_check_without_pop(Register array, Register index) {
   assert_different_registers(array, index, Rtemp);
-  // check array
-  __ null_check(array, Rtemp, arrayOopDesc::length_offset_in_bytes());
   // check index
   __ ldr_s32(Rtemp, Address(array, arrayOopDesc::length_offset_in_bytes()));
   __ cmp_32(index, Rtemp);
@@ -3625,7 +3623,7 @@ void TemplateTable::invokevirtual_helper(Register index,
   __ bind(notFinal);
 
   // get receiver klass
-  __ load_klass_check_null(recv_klass, recv, Rtemp);
+  __ load_klass(recv_klass, recv);
 
   // profile this call
   __ profile_virtual_call(R0_tmp, recv_klass);
@@ -4004,7 +4002,6 @@ void TemplateTable::anewarray() {
 
 void TemplateTable::arraylength() {
   transition(atos, itos);
-  __ null_check(R0_tos, Rtemp, arrayOopDesc::length_offset_in_bytes());
   __ ldr_s32(R0_tos, Address(R0_tos, arrayOopDesc::length_offset_in_bytes()));
 }
 

src/hotspot/cpu/riscv/macroAssembler_riscv.cpp

@@ -2080,11 +2080,6 @@ void MacroAssembler::load_klass(Register dst, Register src, Register tmp) {
   }
 }
 
-void MacroAssembler::load_klass_check_null(Register dst, Register src, Register tmp) {
-  null_check(src, oopDesc::klass_offset_in_bytes());
-  load_klass(dst, src, tmp);
-}
-
 void MacroAssembler::store_klass(Register dst, Register src, Register tmp) {
   // FIXME: Should this be a store release? concurrent gcs assumes
   // klass length is valid if klass field is not null.

src/hotspot/cpu/riscv/macroAssembler_riscv.hpp

@@ -195,7 +195,6 @@ class MacroAssembler: public Assembler {
   void access_store_at(BasicType type, DecoratorSet decorators, Address dst,
                        Register val, Register tmp1, Register tmp2, Register tmp3);
   void load_klass(Register dst, Register src, Register tmp = t0);
-  void load_klass_check_null(Register dst, Register src, Register tmp = t0);
   void store_klass(Register dst, Register src, Register tmp = t0);
   void cmp_klass(Register oop, Register trial_klass, Register tmp1, Register tmp2, Label &L);
 

src/hotspot/cpu/riscv/methodHandles_riscv.cpp

@@ -315,7 +315,7 @@ void MethodHandles::generate_method_handle_dispatch(MacroAssembler* _masm,
         __ null_check(receiver_reg);
       } else {
         // load receiver klass itself
-        __ load_klass_check_null(temp1_recv_klass, receiver_reg);
+        __ load_klass(temp1_recv_klass, receiver_reg);
         __ verify_klass_ptr(temp1_recv_klass);
       }
       BLOCK_COMMENT("check_receiver {");

src/hotspot/cpu/riscv/templateTable_riscv.cpp

@@ -688,8 +688,6 @@ void TemplateTable::wide_aload() {
 
 void TemplateTable::index_check(Register array, Register index) {
   // destroys x11, t0
-  // check array
-  __ null_check(array, arrayOopDesc::length_offset_in_bytes());
   // sign extend index for use by indexed load
   // check index
   const Register length = t0;
@@ -3220,7 +3218,7 @@ void TemplateTable::invokevirtual_helper(Register index,
   __ bind(notFinal);
 
   // get receiver klass
-  __ load_klass_check_null(x10, recv);
+  __ load_klass(x10, recv);
 
   // profile this call
   __ profile_virtual_call(x10, xlocals, x13);
@@ -3304,8 +3302,8 @@ void TemplateTable::invokeinterface(int byte_no) {
   __ andi(t0, x13, 1UL << ConstantPoolCacheEntry::is_vfinal_shift);
   __ beqz(t0, notVFinal);
 
-  // Check receiver klass into x13 - also a null check
-  __ load_klass_check_null(x13, x12);
+  // Check receiver klass into x13
+  __ load_klass(x13, x12);
 
   Label subtype;
   __ check_klass_subtype(x13, x10, x14, subtype);
@@ -3319,9 +3317,9 @@ void TemplateTable::invokeinterface(int byte_no) {
 
   __ bind(notVFinal);
 
-  // Get receiver klass into x13 - also a null check
+  // Get receiver klass into x13
   __ restore_locals();
-  __ load_klass_check_null(x13, x12);
+  __ load_klass(x13, x12);
 
   Label no_such_method;
 
@@ -3558,7 +3556,6 @@ void TemplateTable::anewarray() {
 
 void TemplateTable::arraylength() {
   transition(atos, itos);
-  __ null_check(x10, arrayOopDesc::length_offset_in_bytes());
   __ lwu(x10, Address(x10, arrayOopDesc::length_offset_in_bytes()));
 }
 

src/hotspot/cpu/s390/macroAssembler_s390.cpp

@@ -3651,11 +3651,6 @@ void MacroAssembler::load_klass(Register klass, Register src_oop) {
   }
 }
 
-void MacroAssembler::load_klass_check_null(Register klass, Register src_oop, Register tmp) {
-  null_check(src_oop, tmp, oopDesc::klass_offset_in_bytes());
-  load_klass(klass, src_oop);
-}
-
 void MacroAssembler::store_klass(Register klass, Register dst_oop, Register ck) {
   if (UseCompressedClassPointers) {
     assert_different_registers(dst_oop, klass, Z_R0);

src/hotspot/cpu/s390/macroAssembler_s390.hpp

@@ -766,7 +766,6 @@ class MacroAssembler: public Assembler {
   void decode_klass_not_null(Register dst);
   void load_klass(Register klass, Address mem);
   void load_klass(Register klass, Register src_oop);
-  void load_klass_check_null(Register klass, Register src_oop, Register tmp);
   void store_klass(Register klass, Register dst_oop, Register ck = noreg); // Klass will get compressed if ck not provided.
   void store_klass_gap(Register s, Register dst_oop);
 

src/hotspot/cpu/s390/methodHandles_s390.cpp

@@ -411,7 +411,7 @@ void MethodHandles::generate_method_handle_dispatch(MacroAssembler* _masm,
       __ null_check(receiver_reg);
     } else {
       // Load receiver klass itself.
-      __ load_klass_check_null(temp1_recv_klass, receiver_reg, Z_R0);
+      __ load_klass(temp1_recv_klass, receiver_reg);
       __ verify_klass_ptr(temp1_recv_klass);
     }
     BLOCK_COMMENT("check_receiver {");

src/hotspot/cpu/s390/templateTable_s390.cpp

@@ -774,9 +774,6 @@ void TemplateTable::wide_aload() {
 void TemplateTable::index_check(Register array, Register index, unsigned int shift) {
   assert_different_registers(Z_R1_scratch, array, index);
 
-  // Check array.
-  __ null_check(array, Z_R0_scratch, arrayOopDesc::length_offset_in_bytes());
-
   // Sign extend index for use by indexed load.
   __ z_lgfr(index, index);
 
@@ -3549,7 +3546,7 @@ void TemplateTable::invokevirtual_helper(Register index,
   __ bind(notFinal);
 
   // Get receiver klass.
-  __ load_klass_check_null(Z_tmp_2, recv, Z_R0_scratch);
+  __ load_klass(Z_tmp_2, recv);
 
   // Profile this call.
   __ profile_virtual_call(Z_tmp_2, Z_ARG4, Z_ARG5);
@@ -3924,8 +3921,6 @@ void TemplateTable::arraylength() {
   transition(atos, itos);
 
   int offset = arrayOopDesc::length_offset_in_bytes();
-
-  __ null_check(Z_tos, Z_R0_scratch, offset);
   __ mem2reg_opt(Z_tos, Address(Z_tos, offset), false);
 }
 

src/hotspot/cpu/s390/vtableStubs_s390.cpp

@@ -84,7 +84,7 @@ VtableStub* VtableStubs::create_vtable_stub(int vtable_index) {
   const Register rcvr_klass   = Z_R1_scratch;
   address        npe_addr     = __ pc(); // npe == NULL ptr exception
   // Get receiver klass.
-  __ load_klass_check_null(rcvr_klass, Z_ARG1, Z_R1_scratch);
+  __ load_klass(rcvr_klass, Z_ARG1);
 
 #ifndef PRODUCT
   if (DebugVtables) {
@@ -194,7 +194,7 @@ VtableStub* VtableStubs::create_itable_stub(int itable_index) {
   // Get receiver klass.
   // Must do an explicit check if offset too large or implicit checks are disabled.
   address npe_addr = __ pc(); // npe == NULL ptr exception
-  __ load_klass_check_null(rcvr_klass, Z_ARG1, Z_R1_scratch);
+  __ load_klass(rcvr_klass, Z_ARG1);
 
   // Receiver subtype check against REFC.
   __ z_lg(interface, Address(Z_method, CompiledICHolder::holder_klass_offset()));

src/hotspot/cpu/x86/macroAssembler_x86.cpp

@@ -5131,11 +5131,6 @@ void MacroAssembler::load_klass(Register dst, Register src, Register tmp) {
     movptr(dst, Address(src, oopDesc::klass_offset_in_bytes()));
 }
 
-void MacroAssembler::load_klass_check_null(Register dst, Register src, Register tmp) {
-  null_check(src, oopDesc::klass_offset_in_bytes());
-  load_klass(dst, src, tmp);
-}
-
 void MacroAssembler::store_klass(Register dst, Register src, Register tmp) {
   assert_different_registers(src, tmp);
   assert_different_registers(dst, tmp);

src/hotspot/cpu/x86/macroAssembler_x86.hpp

@@ -362,7 +362,6 @@ class MacroAssembler: public Assembler {
 
   // oop manipulations
   void load_klass(Register dst, Register src, Register tmp);
-  void load_klass_check_null(Register dst, Register src, Register tmp);
   void store_klass(Register dst, Register src, Register tmp);
 
   void access_load_at(BasicType type, DecoratorSet decorators, Register dst, Address src,

src/hotspot/cpu/x86/methodHandles_x86.cpp

@@ -379,7 +379,7 @@ void MethodHandles::generate_method_handle_dispatch(MacroAssembler* _masm,
         __ null_check(receiver_reg);
       } else {
         // load receiver klass itself
-        __ load_klass_check_null(temp1_recv_klass, receiver_reg, temp2);
+        __ load_klass(temp1_recv_klass, receiver_reg, temp2);
         __ verify_klass_ptr(temp1_recv_klass);
       }
       BLOCK_COMMENT("check_receiver {");

src/hotspot/cpu/x86/templateTable_x86.cpp

@@ -750,8 +750,6 @@ void TemplateTable::index_check(Register array, Register index) {
 
 void TemplateTable::index_check_without_pop(Register array, Register index) {
   // destroys rbx
-  // check array
-  __ null_check(array, arrayOopDesc::length_offset_in_bytes());
   // sign extend index for use by indexed load
   __ movl2ptr(index, index);
   // check index
@@ -3729,7 +3727,7 @@ void TemplateTable::invokevirtual_helper(Register index,
   __ bind(notFinal);
 
   // get receiver klass
-  __ load_klass_check_null(rax, recv, rscratch1);
+  __ load_klass(rax, recv, rscratch1);
 
   // profile this call
   __ profile_virtual_call(rax, rlocals, rdx);
@@ -3820,7 +3818,7 @@ void TemplateTable::invokeinterface(int byte_no) {
   __ jcc(Assembler::zero, notVFinal);
 
   // Get receiver klass into rlocals - also a null check
-  __ load_klass_check_null(rlocals, rcx, rscratch1);
+  __ load_klass(rlocals, rcx, rscratch1);
 
   Label subtype;
   __ check_klass_subtype(rlocals, rax, rbcp, subtype);
@@ -3842,7 +3840,7 @@ void TemplateTable::invokeinterface(int byte_no) {
 
   // Get receiver klass into rdx - also a null check
   __ restore_locals();  // restore r14
-  __ load_klass_check_null(rdx, rcx, rscratch1);
+  __ load_klass(rdx, rcx, rscratch1);
 
   Label no_such_method;
 
@@ -4123,7 +4121,6 @@ void TemplateTable::anewarray() {
 
 void TemplateTable::arraylength() {
   transition(atos, itos);
-  __ null_check(rax, arrayOopDesc::length_offset_in_bytes());
   __ movl(rax, Address(rax, arrayOopDesc::length_offset_in_bytes()));
 }
 

src/hotspot/share/memory/universe.cpp

@@ -318,6 +318,12 @@ void Universe::genesis(TRAPS) {
   ResourceMark rm(THREAD);
   HandleMark   hm(THREAD);
 
+  // Explicit null checks are needed if these offsets are not smaller than the page size
+  assert(oopDesc::klass_offset_in_bytes() < static_cast<intptr_t>(os::vm_page_size()),
+         "Klass offset is expected to be less than the page size");
+  assert(arrayOopDesc::length_offset_in_bytes() < static_cast<intptr_t>(os::vm_page_size()),
+         "Array length offset is expected to be less than the page size");
+
   { AutoModifyRestore<bool> temporarily(_bootstrapping, true);
 
     { MutexLocker mc(THREAD, Compile_lock);