Index: compiler-rt/lib/asan/asan_fuchsia.cc
===================================================================
--- compiler-rt/lib/asan/asan_fuchsia.cc
+++ compiler-rt/lib/asan/asan_fuchsia.cc
@@ -196,6 +196,9 @@
   return false;
 }
 
+void FlushUnneededASanShadowMemory(uptr p, uptr size) {
+}
+
 }  // namespace __asan
 
 // These are declared (in extern "C") by <zircon/sanitizer.h>.
Index: compiler-rt/lib/asan/asan_linux.cc
===================================================================
--- compiler-rt/lib/asan/asan_linux.cc
+++ compiler-rt/lib/asan/asan_linux.cc
@@ -254,6 +254,12 @@
   return false;
 }
 
+void FlushUnneededASanShadowMemory(uptr p, uptr size) {
+  // Since asan's mapping is compacting, the shadow chunk may be
+  // not page-aligned, so we only flush the page-aligned portion.
+  ReleaseMemoryPagesToOS(MemToShadow(p), MemToShadow(p + size));
+}
+
 } // namespace __asan
 
 #endif  // SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD ||
Index: compiler-rt/lib/asan/asan_mac.cc
===================================================================
--- compiler-rt/lib/asan/asan_mac.cc
+++ compiler-rt/lib/asan/asan_mac.cc
@@ -203,6 +203,12 @@
   asan_free(context, &stack, FROM_MALLOC);
 }
 
+void FlushUnneededASanShadowMemory(uptr p, uptr size) {
+  // Since asan's mapping is compacting, the shadow chunk may be
+  // not page-aligned, so we only flush the page-aligned portion.
+  ReleaseMemoryPagesToOS(MemToShadow(p), MemToShadow(p + size));
+}
+
 }  // namespace __asan
 
 using namespace __asan;  // NOLINT
Index: compiler-rt/lib/asan/asan_poisoning.cc
===================================================================
--- compiler-rt/lib/asan/asan_poisoning.cc
+++ compiler-rt/lib/asan/asan_poisoning.cc
@@ -62,12 +62,6 @@
   }
 };
 
-void FlushUnneededASanShadowMemory(uptr p, uptr size) {
-  // Since asan's mapping is compacting, the shadow chunk may be
-  // not page-aligned, so we only flush the page-aligned portion.
-  ReleaseMemoryPagesToOS(MemToShadow(p), MemToShadow(p + size));
-}
-
 void AsanPoisonOrUnpoisonIntraObjectRedzone(uptr ptr, uptr size, bool poison) {
   uptr end = ptr + size;
   if (Verbosity()) {
Index: compiler-rt/lib/asan/asan_win.cc
===================================================================
--- compiler-rt/lib/asan/asan_win.cc
+++ compiler-rt/lib/asan/asan_win.cc
@@ -370,6 +370,12 @@
 
 WIN_FORCE_LINK(__asan_dso_reg_hook)
 
+void FlushUnneededASanShadowMemory(uptr p, uptr size) {
+  // Since asan's mapping is compacting, the shadow chunk may be
+  // not page-aligned, so we only flush the page-aligned portion.
+  ReleaseMemoryPagesToOS(MemToShadow(p), MemToShadow(p + size));
+}
+
 // }}}
 }  // namespace __asan