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src/hotspot/share/asm/assembler.cpp
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rev 52430 : 8213199: GC abstraction for Assembler::needs_explicit_null_check()
@@ -24,10 +24,11 @@
#include "precompiled.hpp"
#include "asm/codeBuffer.hpp"
#include "asm/macroAssembler.hpp"
#include "asm/macroAssembler.inline.hpp"
+#include "gc/shared/collectedHeap.hpp"
#include "runtime/atomic.hpp"
#include "runtime/icache.hpp"
#include "runtime/os.hpp"
#include "runtime/thread.hpp"
@@ -305,23 +306,33 @@
return code_section()->outer()->code_string(str);
}
return NULL;
}
-bool MacroAssembler::needs_explicit_null_check(intptr_t offset) {
+bool MacroAssembler::uses_implicit_null_check(void* address) {
// Exception handler checks the nmethod's implicit null checks table
// only when this method returns false.
+ intptr_t int_address = reinterpret_cast<intptr_t>(address);
+ intptr_t cell_header_size = Universe::heap()->cell_header_size();
+ size_t region_size = os::vm_page_size() + cell_header_size;
#ifdef _LP64
if (UseCompressedOops && Universe::narrow_oop_base() != NULL) {
- assert (Universe::heap() != NULL, "java heap should be initialized");
// The first page after heap_base is unmapped and
// the 'offset' is equal to [heap_base + offset] for
// narrow oop implicit null checks.
- uintptr_t base = (uintptr_t)Universe::narrow_oop_base();
- if ((uintptr_t)offset >= base) {
- // Normalize offset for the next check.
- offset = (intptr_t)(pointer_delta((void*)offset, (void*)base, 1));
+ intptr_t start = ((intptr_t)Universe::narrow_oop_base()) - cell_header_size;
+ intptr_t end = start + region_size;
+ if (int_address >= start && int_address < end) {
+ return true;
}
}
#endif
- return offset < 0 || os::vm_page_size() <= offset;
+ intptr_t start = (intptr_t)-cell_header_size;
+ intptr_t end = start + region_size;
+ return int_address >= start && int_address < end;
+}
+
+bool MacroAssembler::needs_explicit_null_check(intptr_t offset) {
+ // Check if offset is outside of [-cell_header_size, os::vm_page_size)
+ return offset < -Universe::heap()->cell_header_size() ||
+ offset >= os::vm_page_size();
}
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