tsan: allow memory overlap in __tsan_java_move

JVM actually moves memory between overlapping ranges.

llvm-svn: 212560

3 files changed, 23 insertions, 6 deletions

diff --git a/compiler-rt/lib/tsan/rtl/tsan_interface_java.cc b/compiler-rt/lib/tsan/rtl/tsan_interface_java.cc
index e63b93f4139..5dfb476dd2e 100644
--- a/compiler-rt/lib/tsan/rtl/tsan_interface_java.cc
+++ b/compiler-rt/lib/tsan/rtl/tsan_interface_java.cc
@@ -126,7 +126,8 @@ void __tsan_java_move(jptr src, jptr dst, jptr size) {
   CHECK_LE(src + size, jctx->heap_begin + jctx->heap_size);
   CHECK_GE(dst, jctx->heap_begin);
   CHECK_LE(dst + size, jctx->heap_begin + jctx->heap_size);
-  CHECK(dst >= src + size || src >= dst + size);
+  CHECK_NE(dst, src);
+  CHECK_NE(size, 0);
 
   // Assuming it's not running concurrently with threads that do
   // memory accesses and mutex operations (stop-the-world phase).
@@ -136,7 +137,14 @@ void __tsan_java_move(jptr src, jptr dst, jptr size) {
   u64 *s = (u64*)MemToShadow(src);
   u64 *d = (u64*)MemToShadow(dst);
   u64 *send = (u64*)MemToShadow(src + size);
-  for (; s != send; s++, d++) {
+  uptr inc = 1;
+  if (dst > src) {
+    s = (u64*)MemToShadow(src + size) - 1;
+    d = (u64*)MemToShadow(dst + size) - 1;
+    send = (u64*)MemToShadow(src) - 1;
+    inc = -1;
+  }
+  for (; s != send; s += inc, d += inc) {
     *d = *s;
     *s = 0;
   }
diff --git a/compiler-rt/lib/tsan/rtl/tsan_interface_java.h b/compiler-rt/lib/tsan/rtl/tsan_interface_java.h
index 6a838851e43..1f793df712d 100644
--- a/compiler-rt/lib/tsan/rtl/tsan_interface_java.h
+++ b/compiler-rt/lib/tsan/rtl/tsan_interface_java.h
@@ -50,7 +50,7 @@ void __tsan_java_alloc(jptr ptr, jptr size) INTERFACE_ATTRIBUTE;
 void __tsan_java_free(jptr ptr, jptr size) INTERFACE_ATTRIBUTE;
 // Callback for memory move by GC.
 // Can be aggregated for several objects (preferably).
-// The ranges must not overlap.
+// The ranges can overlap.
 void __tsan_java_move(jptr src, jptr dst, jptr size) INTERFACE_ATTRIBUTE;
 // This function must be called on the finalizer thread
 // before executing a batch of finalizers.
diff --git a/compiler-rt/lib/tsan/rtl/tsan_sync.cc b/compiler-rt/lib/tsan/rtl/tsan_sync.cc
index 3462b04c21a..15392c9578b 100644
--- a/compiler-rt/lib/tsan/rtl/tsan_sync.cc
+++ b/compiler-rt/lib/tsan/rtl/tsan_sync.cc
@@ -180,13 +180,22 @@ SyncVar* MetaMap::GetAndLock(ThreadState *thr, uptr pc,
 }
 
 void MetaMap::MoveMemory(uptr src, uptr dst, uptr sz) {
-  // Here we assume that src and dst do not overlap,
-  // and there are no concurrent accesses to the regions (e.g. stop-the-world).
+  // src and dst can overlap,
+  // there are no concurrent accesses to the regions (e.g. stop-the-world).
+  CHECK_NE(src, dst);
+  CHECK_NE(sz, 0);
   uptr diff = dst - src;
   u32 *src_meta = MemToMeta(src);
   u32 *dst_meta = MemToMeta(dst);
   u32 *src_meta_end = MemToMeta(src + sz);
-  for (; src_meta != src_meta_end; src_meta++, dst_meta++) {
+  uptr inc = 1;
+  if (dst > src) {
+    src_meta = MemToMeta(src + sz) - 1;
+    dst_meta = MemToMeta(dst + sz) - 1;
+    src_meta_end = MemToMeta(src) - 1;
+    inc = -1;
+  }
+  for (; src_meta != src_meta_end; src_meta += inc, dst_meta += inc) {
     CHECK_EQ(*dst_meta, 0);
     u32 idx = *src_meta;
     *src_meta = 0;