Mercurial > hg > graal-jvmci-8
comparison src/share/vm/asm/assembler.cpp @ 237:1fdb98a17101
6716785: implicit null checks not triggering with CompressedOops
Summary: allocate alignment-sized page(s) below java heap so that memory accesses at heap_base+1page give signal and cause an implicit null check
Reviewed-by: kvn, jmasa, phh, jcoomes
| author | coleenp |
|---|---|
| date | Sat, 19 Jul 2008 17:38:22 -0400 |
| parents | a61af66fc99e |
| children | 9ee9cf798b59 36ccc817fca4 |
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| 235:9c2ecc2ffb12 | 237:1fdb98a17101 |
|---|---|
| 244 if (sect() == CodeBuffer::SECT_INSTS) { | 244 if (sect() == CodeBuffer::SECT_INSTS) { |
| 245 code_section()->outer()->block_comment(offset(), comment); | 245 code_section()->outer()->block_comment(offset(), comment); |
| 246 } | 246 } |
| 247 } | 247 } |
| 248 | 248 |
| 249 bool MacroAssembler::needs_explicit_null_check(intptr_t offset) { | |
| 250 // Exception handler checks the nmethod's implicit null checks table | |
| 251 // only when this method returns false. | |
| 252 #ifndef SPARC | |
| 253 // Sparc does not have based addressing | |
| 254 if (UseCompressedOops) { | |
| 255 // The first page after heap_base is unmapped and | |
| 256 // the 'offset' is equal to [heap_base + offset] for | |
| 257 // narrow oop implicit null checks. | |
| 258 uintptr_t heap_base = (uintptr_t)Universe::heap_base(); | |
| 259 if ((uintptr_t)offset >= heap_base) { | |
| 260 // Normalize offset for the next check. | |
| 261 offset = (intptr_t)(pointer_delta((void*)offset, (void*)heap_base, 1)); | |
| 262 } | |
| 263 } | |
| 264 #endif // SPARC | |
| 265 return offset < 0 || os::vm_page_size() <= offset; | |
| 266 } | |
| 249 | 267 |
| 250 #ifndef PRODUCT | 268 #ifndef PRODUCT |
| 251 void Label::print_instructions(MacroAssembler* masm) const { | 269 void Label::print_instructions(MacroAssembler* masm) const { |
| 252 CodeBuffer* cb = masm->code(); | 270 CodeBuffer* cb = masm->code(); |
| 253 for (int i = 0; i < _patch_index; ++i) { | 271 for (int i = 0; i < _patch_index; ++i) { |