8270083: -Wnonnull errors happen with GCC 11.1.1

make/hotspot/lib/JvmOverrideFiles.gmk

@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2013, 2020, Oracle and/or its affiliates. All rights reserved.
+# Copyright (c) 2013, 2021, Oracle and/or its affiliates. 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
@@ -36,6 +36,7 @@ ifeq ($(TOOLCHAIN_TYPE), gcc)
   BUILD_LIBJVM_assembler_x86.cpp_CXXFLAGS := -Wno-maybe-uninitialized
   BUILD_LIBJVM_cardTableBarrierSetAssembler_x86.cpp_CXXFLAGS := -Wno-maybe-uninitialized
   BUILD_LIBJVM_interp_masm_x86.cpp_CXXFLAGS := -Wno-uninitialized
+  BUILD_LIBJVM_ad_$(HOTSPOT_TARGET_CPU_ARCH).cpp_CXXFLAGS := -Wno-nonnull
   ifeq ($(DEBUG_LEVEL), release)
     # Need extra inlining to collapse shared marking code into the hot marking loop
     BUILD_LIBJVM_shenandoahMark.cpp_CXXFLAGS := --param inline-unit-growth=1000

src/hotspot/cpu/x86/assembler_x86.cpp

@@ -7546,6 +7546,10 @@ void Assembler::evprolq(XMMRegister dst, XMMRegister src, int shift, int vector_
   emit_int24(0x72, (0xC0 | encode), shift & 0xFF);
 }
 
+// Register is a class, but it would be assigned numerical value.
+// "0" is assigned for xmm0. Thus we need to ignore -Wnonnull.
+PRAGMA_DIAG_PUSH
+PRAGMA_NONNULL_IGNORED
 void Assembler::evprord(XMMRegister dst, XMMRegister src, int shift, int vector_len) {
   assert(VM_Version::supports_evex(), "requires EVEX support");
   assert(vector_len == Assembler::AVX_512bit || VM_Version::supports_avx512vl(), "requires VL support");
@@ -7563,6 +7567,7 @@ void Assembler::evprorq(XMMRegister dst, XMMRegister src, int shift, int vector_
   int encode = vex_prefix_and_encode(xmm0->encoding(), dst->encoding(), src->encoding(), VEX_SIMD_66, VEX_OPCODE_0F, &attributes);
   emit_int24(0x72, (0xC0 | encode), shift & 0xFF);
 }
+PRAGMA_DIAG_POP
 
 void Assembler::evprolvd(XMMRegister dst, XMMRegister src, XMMRegister shift, int vector_len) {
   assert(VM_Version::supports_evex(), "requires EVEX support");

src/hotspot/cpu/x86/c1_Runtime1_x86.cpp

@@ -318,7 +318,11 @@ enum reg_save_layout {
 // expensive.  The deopt blob is the only thing which needs to
 // describe FPU registers.  In all other cases it should be sufficient
 // to simply save their current value.
-
+//
+// Register is a class, but it would be assigned numerical value.
+// "0" is assigned for rax. Thus we need to ignore -Wnonnull.
+PRAGMA_DIAG_PUSH
+PRAGMA_NONNULL_IGNORED
 static OopMap* generate_oop_map(StubAssembler* sasm, int num_rt_args,
                                 bool save_fpu_registers = true) {
 
@@ -418,6 +422,7 @@ static OopMap* generate_oop_map(StubAssembler* sasm, int num_rt_args,
 
   return map;
 }
+PRAGMA_DIAG_POP
 
 #define __ this->
 

src/hotspot/cpu/x86/frame_x86.inline.hpp

@@ -230,6 +230,10 @@ inline JavaCallWrapper** frame::entry_frame_call_wrapper_addr() const {
 
 // Compiled frames
 
+// Register is a class, but it would be assigned numerical value.
+// "0" is assigned for rax. Thus we need to ignore -Wnonnull.
+PRAGMA_DIAG_PUSH
+PRAGMA_NONNULL_IGNORED
 inline oop frame::saved_oop_result(RegisterMap* map) const {
   oop* result_adr = (oop *)map->location(rax->as_VMReg());
   guarantee(result_adr != NULL, "bad register save location");
@@ -243,5 +247,6 @@ inline void frame::set_saved_oop_result(RegisterMap* map, oop obj) {
 
   *result_adr = obj;
 }
+PRAGMA_DIAG_POP
 
 #endif // CPU_X86_FRAME_X86_INLINE_HPP

src/hotspot/cpu/x86/gc/z/zBarrierSetAssembler_x86.cpp

@@ -465,6 +465,10 @@ class ZSaveLiveRegisters {
     _spill_offset += 8;
   }
 
+// Register is a class, but it would be assigned numerical value.
+// "0" is assigned for rax. Thus we need to ignore -Wnonnull.
+PRAGMA_DIAG_PUSH
+PRAGMA_NONNULL_IGNORED
   void initialize(ZLoadBarrierStubC2* stub) {
     // Create mask of caller saved registers that need to
     // be saved/restored if live
@@ -540,6 +544,7 @@ class ZSaveLiveRegisters {
     // Stack pointer must be 16 bytes aligned for the call
     _spill_offset = _spill_size = align_up(xmm_spill_size + gp_spill_size + opmask_spill_size + arg_spill_size, 16);
   }
+PRAGMA_DIAG_POP
 
 public:
   ZSaveLiveRegisters(MacroAssembler* masm, ZLoadBarrierStubC2* stub) :

src/hotspot/cpu/x86/sharedRuntime_x86_64.cpp

@@ -168,6 +168,10 @@ class RegisterSaver {
   static void restore_result_registers(MacroAssembler* masm);
 };
 
+// Register is a class, but it would be assigned numerical value.
+// "0" is assigned for rax. Thus we need to ignore -Wnonnull.
+PRAGMA_DIAG_PUSH
+PRAGMA_NONNULL_IGNORED
 OopMap* RegisterSaver::save_live_registers(MacroAssembler* masm, int additional_frame_words, int* total_frame_words, bool save_wide_vectors) {
   int off = 0;
   int num_xmm_regs = XMMRegisterImpl::number_of_registers;
@@ -361,6 +365,7 @@ OopMap* RegisterSaver::save_live_registers(MacroAssembler* masm, int additional_
 
   return map;
 }
+PRAGMA_DIAG_POP
 
 void RegisterSaver::restore_live_registers(MacroAssembler* masm, bool restore_wide_vectors) {
   int num_xmm_regs = XMMRegisterImpl::number_of_registers;

src/hotspot/cpu/x86/universalUpcallHandler_x86_64.cpp

@@ -587,6 +587,10 @@ static void shuffle_arguments(MacroAssembler* _masm, const GrowableArray<ArgMove
   }
 }
 
+// Register is a class, but it would be assigned numerical value.
+// "0" is assigned for rax and for xmm0. Thus we need to ignore -Wnonnull.
+PRAGMA_DIAG_PUSH
+PRAGMA_NONNULL_IGNORED
 address ProgrammableUpcallHandler::generate_optimized_upcall_stub(jobject receiver, Method* entry, jobject jabi, jobject jconv) {
   ResourceMark rm;
   const ABIDescriptor abi = ForeignGlobals::parse_abi_descriptor(jabi);
@@ -779,6 +783,7 @@ address ProgrammableUpcallHandler::generate_optimized_upcall_stub(jobject receiv
 
   return blob->code_begin();
 }
+PRAGMA_DIAG_POP
 
 bool ProgrammableUpcallHandler::supports_optimized_upcalls() {
   return true;

src/hotspot/share/utilities/compilerWarnings.hpp

@@ -74,4 +74,8 @@
 #define PRAGMA_INFINITE_RECURSION_IGNORED
 #endif
 
+#ifndef PRAGMA_NONNULL_IGNORED
+#define PRAGMA_NONNULL_IGNORED
+#endif
+
 #endif // SHARE_UTILITIES_COMPILERWARNINGS_HPP

src/hotspot/share/utilities/compilerWarnings_gcc.hpp

@@ -58,6 +58,9 @@
 #define PRAGMA_STRINGOP_TRUNCATION_IGNORED PRAGMA_DISABLE_GCC_WARNING("-Wstringop-truncation")
 #endif
 
+#define PRAGMA_NONNULL_IGNORED \
+  PRAGMA_DISABLE_GCC_WARNING("-Wnonnull")
+
 #if defined(__clang_major__) && \
       (__clang_major__ >= 4 || \
       (__clang_major__ >= 3 && __clang_minor__ >= 1)) || \