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comparison src/share/vm/asm/assembler.cpp @ 642:660978a2a31a

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6791178: Specialize for zero as the compressed oop vm heap base Summary: Use zero based compressed oops if java heap is below 32gb and unscaled compressed oops if java heap is below 4gb. Reviewed-by: never, twisti, jcoomes, coleenp
author kvn
date Thu, 12 Mar 2009 10:37:46 -0700
parents 56aae7be60d4
children bd02caa94611
comparison
equal deleted inserted replaced
641:6af0a709d52b 642:660978a2a31a
319 } 319 }
320 320
321 bool MacroAssembler::needs_explicit_null_check(intptr_t offset) { 321 bool MacroAssembler::needs_explicit_null_check(intptr_t offset) {
322 // Exception handler checks the nmethod's implicit null checks table 322 // Exception handler checks the nmethod's implicit null checks table
323 // only when this method returns false. 323 // only when this method returns false.
324 if (UseCompressedOops) { 324 #ifdef _LP64
325 if (UseCompressedOops && Universe::narrow_oop_base() != NULL) {
326 assert (Universe::heap() != NULL, "java heap should be initialized");
325 // The first page after heap_base is unmapped and 327 // The first page after heap_base is unmapped and
326 // the 'offset' is equal to [heap_base + offset] for 328 // the 'offset' is equal to [heap_base + offset] for
327 // narrow oop implicit null checks. 329 // narrow oop implicit null checks.
328 uintptr_t heap_base = (uintptr_t)Universe::heap_base(); 330 uintptr_t base = (uintptr_t)Universe::narrow_oop_base();
329 if ((uintptr_t)offset >= heap_base) { 331 if ((uintptr_t)offset >= base) {
330 // Normalize offset for the next check. 332 // Normalize offset for the next check.
331 offset = (intptr_t)(pointer_delta((void*)offset, (void*)heap_base, 1)); 333 offset = (intptr_t)(pointer_delta((void*)offset, (void*)base, 1));
332 } 334 }
333 } 335 }
336 #endif
334 return offset < 0 || os::vm_page_size() <= offset; 337 return offset < 0 || os::vm_page_size() <= offset;
335 } 338 }
336 339
337 #ifndef PRODUCT 340 #ifndef PRODUCT
338 void Label::print_instructions(MacroAssembler* masm) const { 341 void Label::print_instructions(MacroAssembler* masm) const {