jdk-sandbox: comparison hotspot/src/cpu/x86/vm/assembler

equal deleted inserted replaced

-:bfbfaacd23e5
+:4846648c4b7b
 // Skip to start of data.
 addptr(rdi, arrayOopDesc::base_offset_in_bytes(T_OBJECT));
 // Scan RCX words at [RDI] for an occurrence of RAX.
 // Set NZ/Z based on last compare.
+// Z flag value will not be set by 'repne' if RCX == 0 since 'repne' does
+// not change flags (only scas instruction which is repeated sets flags).
+// Set Z = 0 (not equal) before 'repne' to indicate that class was not found.
 #ifdef _LP64
 // This part is tricky, as values in supers array could be 32 or 64 bit wide
 // and we store values in objArrays always encoded, thus we need to encode
 // the value of rax before repne.  Note that rax is dead after the repne.
 if (UseCompressedOops) {
-encode_heap_oop_not_null(rax);
+encode_heap_oop_not_null(rax); // Changes flags.
 // The superclass is never null; it would be a basic system error if a null
 // pointer were to sneak in here.  Note that we have already loaded the
 // Klass::super_check_offset from the super_klass in the fast path,
 // so if there is a null in that register, we are already in the afterlife.
+testl(rax,rax); // Set Z = 0
 repne_scanl();
 } else
 #endif // _LP64
+{
+testptr(rax,rax); // Set Z = 0
 repne_scan();
+}
 // Unspill the temp. registers:
 if (pushed_rdi)  pop(rdi);
 if (pushed_rcx)  pop(rcx);
 if (pushed_rax)  pop(rax);
 } else {
 movslq(dst, (int32_t)NULL_WORD);
 }
 }
+#ifdef ASSERT
+void MacroAssembler::verify_heapbase(const char* msg) {
+assert (UseCompressedOops, "should be compressed");
+assert (Universe::heap() != NULL, "java heap should be initialized");
+if (CheckCompressedOops) {
+Label ok;
+push(rscratch1); // cmpptr trashes rscratch1
+cmpptr(r12_heapbase, ExternalAddress((address)Universe::narrow_oop_base_addr()));
+jcc(Assembler::equal, ok);
+stop(msg);
+bind(ok);
+pop(rscratch1);
+}
+}
+#endif
 // Algorithm must match oop.inline.hpp encode_heap_oop.
 void MacroAssembler::encode_heap_oop(Register r) {
-assert (UseCompressedOops, "should be compressed");
+#ifdef ASSERT
-assert (Universe::heap() != NULL, "java heap should be initialized");
+verify_heapbase("MacroAssembler::encode_heap_oop: heap base corrupted?");
+#endif
+verify_oop(r, "broken oop in encode_heap_oop");
 if (Universe::narrow_oop_base() == NULL) {
-verify_oop(r, "broken oop in encode_heap_oop");
 if (Universe::narrow_oop_shift() != 0) {
 assert (LogMinObjAlignmentInBytes == Universe::narrow_oop_shift(), "decode alg wrong");
 shrq(r, LogMinObjAlignmentInBytes);
 }
 return;
 }
-#ifdef ASSERT
-if (CheckCompressedOops) {
-Label ok;
-push(rscratch1); // cmpptr trashes rscratch1
-cmpptr(r12_heapbase, ExternalAddress((address)Universe::narrow_oop_base_addr()));
-jcc(Assembler::equal, ok);
-stop("MacroAssembler::encode_heap_oop: heap base corrupted?");
-bind(ok);
-pop(rscratch1);
-}
-#endif
-verify_oop(r, "broken oop in encode_heap_oop");
 testq(r, r);
 cmovq(Assembler::equal, r, r12_heapbase);
 subq(r, r12_heapbase);
 shrq(r, LogMinObjAlignmentInBytes);
 }
 void MacroAssembler::encode_heap_oop_not_null(Register r) {
-assert (UseCompressedOops, "should be compressed");
-assert (Universe::heap() != NULL, "java heap should be initialized");
 #ifdef ASSERT
+verify_heapbase("MacroAssembler::encode_heap_oop_not_null: heap base corrupted?");
 if (CheckCompressedOops) {
 Label ok;
 testq(r, r);
 jcc(Assembler::notEqual, ok);
 stop("null oop passed to encode_heap_oop_not_null");
 shrq(r, LogMinObjAlignmentInBytes);
 }
 }
 void MacroAssembler::encode_heap_oop_not_null(Register dst, Register src) {
-assert (UseCompressedOops, "should be compressed");
-assert (Universe::heap() != NULL, "java heap should be initialized");
 #ifdef ASSERT
+verify_heapbase("MacroAssembler::encode_heap_oop_not_null2: heap base corrupted?");
 if (CheckCompressedOops) {
 Label ok;
 testq(src, src);
 jcc(Assembler::notEqual, ok);
 stop("null oop passed to encode_heap_oop_not_null2");
 shrq(dst, LogMinObjAlignmentInBytes);
 }
 }
 void  MacroAssembler::decode_heap_oop(Register r) {
-assert (UseCompressedOops, "should be compressed");
+#ifdef ASSERT
-assert (Universe::heap() != NULL, "java heap should be initialized");
+verify_heapbase("MacroAssembler::decode_heap_oop: heap base corrupted?");
+#endif
 if (Universe::narrow_oop_base() == NULL) {
 if (Universe::narrow_oop_shift() != 0) {
 assert (LogMinObjAlignmentInBytes == Universe::narrow_oop_shift(), "decode alg wrong");
 shlq(r, LogMinObjAlignmentInBytes);
 }
-verify_oop(r, "broken oop in decode_heap_oop");
+} else {
-return;
+Label done;
-}
+shlq(r, LogMinObjAlignmentInBytes);
-#ifdef ASSERT
+jccb(Assembler::equal, done);
-if (CheckCompressedOops) {
+addq(r, r12_heapbase);
-Label ok;
+bind(done);
-push(rscratch1);
+}
-cmpptr(r12_heapbase,
-ExternalAddress((address)Universe::narrow_oop_base_addr()));
-jcc(Assembler::equal, ok);
-stop("MacroAssembler::decode_heap_oop: heap base corrupted?");
-bind(ok);
-pop(rscratch1);
-}
-#endif
-Label done;
-shlq(r, LogMinObjAlignmentInBytes);
-jccb(Assembler::equal, done);
-addq(r, r12_heapbase);
-#if 0
-// alternate decoding probably a wash.
-testq(r, r);
-jccb(Assembler::equal, done);
-leaq(r, Address(r12_heapbase, r, Address::times_8, 0));
-#endif
-bind(done);
 verify_oop(r, "broken oop in decode_heap_oop");
 }
 void  MacroAssembler::decode_heap_oop_not_null(Register r) {
 // Note: it will change flags
 shlq(dst, LogMinObjAlignmentInBytes);
 if (Universe::narrow_oop_base() != NULL) {
 addq(dst, r12_heapbase);
 }
 }
-} else if (dst != src) {
+} else {
 assert (Universe::narrow_oop_base() == NULL, "sanity");
-movq(dst, src);
+if (dst != src) {
+movq(dst, src);
+}
 }
 }
 void  MacroAssembler::set_narrow_oop(Register dst, jobject obj) {
 assert (UseCompressedOops, "should only be used for compressed headers");

changeset 6179	4846648c4b7b
parent 5706	0c91076143f9
child 6185	1d2b3c0c9674