tsan: allow Java VM iterate over allocated objects

Objects may move during the garbage collection, and JVM needs
to notify ThreadAnalyzer about that. The new function
__tsan_java_find eliminates the need to maintain these
objects both in ThreadAnalyzer and JVM.

Author: Alexander Smundak (asmundak)
Reviewed in https://reviews.llvm.org/D27720

llvm-svn: 289682

compiler-rt/lib/tsan/rtl/tsan_interface_java.cc

@@ -150,6 +150,23 @@ void __tsan_java_move(jptr src, jptr dst, jptr size) {
   }
 }
 
+jptr __tsan_java_find(jptr *from_ptr, jptr to) {
+  SCOPED_JAVA_FUNC(__tsan_java_find);
+  DPrintf("#%d: java_find(&%p, %p)\n", *from_ptr, to);
+  CHECK_EQ((*from_ptr) % kHeapAlignment, 0);
+  CHECK_EQ(to % kHeapAlignment, 0);
+  CHECK_GE(*from_ptr, jctx->heap_begin);
+  CHECK_LE(to, jctx->heap_begin + jctx->heap_size);
+  for (uptr from = *from_ptr; from < to; from += kHeapAlignment) {
+    MBlock *b = ctx->metamap.GetBlock(from);
+    if (b) {
+      *from_ptr = from;
+      return b->siz;
+    }
+  }
+  return 0;
+}
+
 void __tsan_java_finalize() {
   SCOPED_JAVA_FUNC(__tsan_java_finalize);
   DPrintf("#%d: java_mutex_finalize()\n", thr->tid);

compiler-rt/lib/tsan/rtl/tsan_interface_java.h

@@ -57,6 +57,10 @@ void __tsan_java_move(jptr src, jptr dst, jptr size) INTERFACE_ATTRIBUTE;
 // It ensures necessary synchronization between
 // java object creation and finalization.
 void __tsan_java_finalize() INTERFACE_ATTRIBUTE;
+// Finds the first allocated memory block in the [*from_ptr, to) range, saves
+// its address in *from_ptr and returns its size. Returns 0 if there are no
+// allocated memory blocks in the range.
+jptr __tsan_java_find(jptr *from_ptr, jptr to) INTERFACE_ATTRIBUTE;
 
 // Mutex lock.
 // Addr is any unique address associated with the mutex.

compiler-rt/test/tsan/java.h

@@ -7,6 +7,7 @@ void __tsan_java_init(jptr heap_begin, jptr heap_size);
 int  __tsan_java_fini();
 void __tsan_java_alloc(jptr ptr, jptr size);
 void __tsan_java_free(jptr ptr, jptr size);
+jptr __tsan_java_find(jptr *from_ptr, jptr to);
 void __tsan_java_move(jptr src, jptr dst, jptr size);
 void __tsan_java_finalize();
 void __tsan_java_mutex_lock(jptr addr);