提交 a8f52a82 编写于 作者: G goetz

8028471: PPC64 (part 215): opto: Extend ImplicitNullCheck optimization.

Summary: Fixed Implicit NULL check optimization for AIX, where the page at address '0' is only write-protected.
Reviewed-by: kvn
上级 07dea506
...@@ -92,7 +92,7 @@ define_pd_global(uintx, TypeProfileLevel, 0); ...@@ -92,7 +92,7 @@ define_pd_global(uintx, TypeProfileLevel, 0);
/* Trap based checks use the ppc trap instructions to check certain */ \ /* Trap based checks use the ppc trap instructions to check certain */ \
/* conditions. This instruction raises a SIGTRAP caught by the */ \ /* conditions. This instruction raises a SIGTRAP caught by the */ \
/* exception handler of the VM. */ \ /* exception handler of the VM. */ \
product(bool, UseSIGTRAP, false, \ product(bool, UseSIGTRAP, true, \
"Allow trap instructions that make use of SIGTRAP. Use this to " \ "Allow trap instructions that make use of SIGTRAP. Use this to " \
"switch off all optimizations requiring SIGTRAP.") \ "switch off all optimizations requiring SIGTRAP.") \
product(bool, TrapBasedICMissChecks, true, \ product(bool, TrapBasedICMissChecks, true, \
......
...@@ -2433,7 +2433,7 @@ void MacroAssembler::load_klass(Register dst, Register src) { ...@@ -2433,7 +2433,7 @@ void MacroAssembler::load_klass(Register dst, Register src) {
} }
void MacroAssembler::load_klass_with_trap_null_check(Register dst, Register src) { void MacroAssembler::load_klass_with_trap_null_check(Register dst, Register src) {
if (false NOT_LINUX(|| true) /*!os::zero_page_read_protected()*/) { if (!os::zero_page_read_protected()) {
if (TrapBasedNullChecks) { if (TrapBasedNullChecks) {
trap_null_check(src); trap_null_check(src);
} }
......
...@@ -269,7 +269,7 @@ inline void MacroAssembler::trap_ic_miss_check(Register a, Register b) { ...@@ -269,7 +269,7 @@ inline void MacroAssembler::trap_ic_miss_check(Register a, Register b) {
// No support for compressed oops (base page of heap). Does not distinguish // No support for compressed oops (base page of heap). Does not distinguish
// loads and stores. // loads and stores.
inline void MacroAssembler::null_check_throw(Register a, int offset, Register temp_reg, address exception_entry) { inline void MacroAssembler::null_check_throw(Register a, int offset, Register temp_reg, address exception_entry) {
if (!ImplicitNullChecks || needs_explicit_null_check(offset) NOT_LINUX(|| true) /*!os::zero_page_read_protected()*/) { if (!ImplicitNullChecks || needs_explicit_null_check(offset) || !os::zero_page_read_protected()) {
if (TrapBasedNullChecks) { if (TrapBasedNullChecks) {
assert(UseSIGTRAP, "sanity"); assert(UseSIGTRAP, "sanity");
trap_null_check(a); trap_null_check(a);
...@@ -286,7 +286,7 @@ inline void MacroAssembler::null_check_throw(Register a, int offset, Register te ...@@ -286,7 +286,7 @@ inline void MacroAssembler::null_check_throw(Register a, int offset, Register te
} }
inline void MacroAssembler::ld_with_trap_null_check(Register d, int si16, Register s1) { inline void MacroAssembler::ld_with_trap_null_check(Register d, int si16, Register s1) {
if ( NOT_LINUX(true) LINUX_ONLY(false)/*!os::zero_page_read_protected()*/) { if (!os::zero_page_read_protected()) {
if (TrapBasedNullChecks) { if (TrapBasedNullChecks) {
trap_null_check(s1); trap_null_check(s1);
} }
...@@ -297,7 +297,7 @@ inline void MacroAssembler::ld_with_trap_null_check(Register d, int si16, Regist ...@@ -297,7 +297,7 @@ inline void MacroAssembler::ld_with_trap_null_check(Register d, int si16, Regist
// Attention: No null check for loaded uncompressed OOP. Can be used for loading klass field. // Attention: No null check for loaded uncompressed OOP. Can be used for loading klass field.
inline void MacroAssembler::load_heap_oop_with_trap_null_check(Register d, RegisterOrConstant si16, inline void MacroAssembler::load_heap_oop_with_trap_null_check(Register d, RegisterOrConstant si16,
Register s1) { Register s1) {
if ( NOT_LINUX(true)LINUX_ONLY(false) /*!os::zero_page_read_protected()*/) { if ( !os::zero_page_read_protected()) {
if (TrapBasedNullChecks) { if (TrapBasedNullChecks) {
trap_null_check(s1); trap_null_check(s1);
} }
......
...@@ -1128,7 +1128,7 @@ AdapterHandlerEntry* SharedRuntime::generate_i2c2i_adapters(MacroAssembler *masm ...@@ -1128,7 +1128,7 @@ AdapterHandlerEntry* SharedRuntime::generate_i2c2i_adapters(MacroAssembler *masm
assert(!MacroAssembler::needs_explicit_null_check(oopDesc::klass_offset_in_bytes()), assert(!MacroAssembler::needs_explicit_null_check(oopDesc::klass_offset_in_bytes()),
"klass offset should reach into any page"); "klass offset should reach into any page");
// Check for NULL argument if we don't have implicit null checks. // Check for NULL argument if we don't have implicit null checks.
if (!ImplicitNullChecks NOT_LINUX(|| true) /*!os::zero_page_read_protected()*/) { if (!ImplicitNullChecks || !os::zero_page_read_protected()) {
if (TrapBasedNullChecks) { if (TrapBasedNullChecks) {
__ trap_null_check(R3_ARG1); __ trap_null_check(R3_ARG1);
} else { } else {
......
...@@ -221,7 +221,7 @@ VtableStub* VtableStubs::create_itable_stub(int vtable_index) { ...@@ -221,7 +221,7 @@ VtableStub* VtableStubs::create_itable_stub(int vtable_index) {
// Must do an explicit check if implicit checks are disabled. // Must do an explicit check if implicit checks are disabled.
assert(!MacroAssembler::needs_explicit_null_check(in_bytes(Method::from_compiled_offset())), "sanity"); assert(!MacroAssembler::needs_explicit_null_check(in_bytes(Method::from_compiled_offset())), "sanity");
if (!ImplicitNullChecks NOT_LINUX(|| true) /*!os::zero_page_read_protected()*/) { if (!ImplicitNullChecks || !os::zero_page_read_protected()) {
if (TrapBasedNullChecks) { if (TrapBasedNullChecks) {
__ trap_null_check(R19_method); __ trap_null_check(R19_method);
} else { } else {
......
...@@ -27,6 +27,9 @@ ...@@ -27,6 +27,9 @@
// Bsd_OS defines the interface to Bsd operating systems // Bsd_OS defines the interface to Bsd operating systems
// Information about the protection of the page at address '0' on this os.
static bool zero_page_read_protected() { return true; }
/* pthread_getattr_np comes with BsdThreads-0.9-7 on RedHat 7.1 */ /* pthread_getattr_np comes with BsdThreads-0.9-7 on RedHat 7.1 */
typedef int (*pthread_getattr_func_type) (pthread_t, pthread_attr_t *); typedef int (*pthread_getattr_func_type) (pthread_t, pthread_attr_t *);
......
...@@ -30,6 +30,9 @@ ...@@ -30,6 +30,9 @@
/* pthread_getattr_np comes with LinuxThreads-0.9-7 on RedHat 7.1 */ /* pthread_getattr_np comes with LinuxThreads-0.9-7 on RedHat 7.1 */
typedef int (*pthread_getattr_func_type) (pthread_t, pthread_attr_t *); typedef int (*pthread_getattr_func_type) (pthread_t, pthread_attr_t *);
// Information about the protection of the page at address '0' on this os.
static bool zero_page_read_protected() { return true; }
class Linux { class Linux {
friend class os; friend class os;
friend class TestReserveMemorySpecial; friend class TestReserveMemorySpecial;
......
...@@ -27,6 +27,9 @@ ...@@ -27,6 +27,9 @@
// Solaris_OS defines the interface to Solaris operating systems // Solaris_OS defines the interface to Solaris operating systems
// Information about the protection of the page at address '0' on this os.
static bool zero_page_read_protected() { return true; }
class Solaris { class Solaris {
friend class os; friend class os;
......
...@@ -26,6 +26,9 @@ ...@@ -26,6 +26,9 @@
#define OS_WINDOWS_VM_OS_WINDOWS_HPP #define OS_WINDOWS_VM_OS_WINDOWS_HPP
// Win32_OS defines the interface to windows operating systems // Win32_OS defines the interface to windows operating systems
// Information about the protection of the page at address '0' on this os.
static bool zero_page_read_protected() { return true; }
class win32 { class win32 {
friend class os; friend class os;
......
...@@ -201,7 +201,7 @@ JVMState* VirtualCallGenerator::generate(JVMState* jvms, Parse* parent_parser) { ...@@ -201,7 +201,7 @@ JVMState* VirtualCallGenerator::generate(JVMState* jvms, Parse* parent_parser) {
// Block::implicit_null_check() only looks for loads and stores, not calls. // Block::implicit_null_check() only looks for loads and stores, not calls.
ciMethod *caller = kit.method(); ciMethod *caller = kit.method();
ciMethodData *caller_md = (caller == NULL) ? NULL : caller->method_data(); ciMethodData *caller_md = (caller == NULL) ? NULL : caller->method_data();
if (!UseInlineCaches || !ImplicitNullChecks || if (!UseInlineCaches || !ImplicitNullChecks || !os::zero_page_read_protected() ||
((ImplicitNullCheckThreshold > 0) && caller_md && ((ImplicitNullCheckThreshold > 0) && caller_md &&
(caller_md->trap_count(Deoptimization::Reason_null_check) (caller_md->trap_count(Deoptimization::Reason_null_check)
>= (uint)ImplicitNullCheckThreshold))) { >= (uint)ImplicitNullCheckThreshold))) {
......
...@@ -54,6 +54,43 @@ ...@@ -54,6 +54,43 @@
// Optimization - Graph Style // Optimization - Graph Style
// Check whether val is not-null-decoded compressed oop,
// i.e. will grab into the base of the heap if it represents NULL.
static bool accesses_heap_base_zone(Node *val) {
if (Universe::narrow_oop_base() > 0) { // Implies UseCompressedOops.
if (val && val->is_Mach()) {
if (val->as_Mach()->ideal_Opcode() == Op_DecodeN) {
// This assumes all Decodes with TypePtr::NotNull are matched to nodes that
// decode NULL to point to the heap base (Decode_NN).
if (val->bottom_type()->is_oopptr()->ptr() == TypePtr::NotNull) {
return true;
}
}
// Must recognize load operation with Decode matched in memory operand.
// We should not reach here exept for PPC/AIX, as os::zero_page_read_protected()
// returns true everywhere else. On PPC, no such memory operands
// exist, therefore we did not yet implement a check for such operands.
NOT_AIX(Unimplemented());
}
}
return false;
}
static bool needs_explicit_null_check_for_read(Node *val) {
// On some OSes (AIX) the page at address 0 is only write protected.
// If so, only Store operations will trap.
if (os::zero_page_read_protected()) {
return false; // Implicit null check will work.
}
// Also a read accessing the base of a heap-based compressed heap will trap.
if (accesses_heap_base_zone(val) && // Hits the base zone page.
Universe::narrow_oop_use_implicit_null_checks()) { // Base zone page is protected.
return false;
}
return true;
}
//------------------------------implicit_null_check---------------------------- //------------------------------implicit_null_check----------------------------
// Detect implicit-null-check opportunities. Basically, find NULL checks // Detect implicit-null-check opportunities. Basically, find NULL checks
// with suitable memory ops nearby. Use the memory op to do the NULL check. // with suitable memory ops nearby. Use the memory op to do the NULL check.
...@@ -209,6 +246,14 @@ void PhaseCFG::implicit_null_check(Block* block, Node *proj, Node *val, int allo ...@@ -209,6 +246,14 @@ void PhaseCFG::implicit_null_check(Block* block, Node *proj, Node *val, int allo
} }
break; break;
} }
// On some OSes (AIX) the page at address 0 is only write protected.
// If so, only Store operations will trap.
// But a read accessing the base of a heap-based compressed heap will trap.
if (!was_store && needs_explicit_null_check_for_read(val)) {
continue;
}
// check if the offset is not too high for implicit exception // check if the offset is not too high for implicit exception
{ {
intptr_t offset = 0; intptr_t offset = 0;
......
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