1 files changed, 76 insertions, 0 deletions
diff --git a/test/builtins/Unit/clear_cache_test.c b/test/builtins/Unit/clear_cache_test.c
new file mode 100644
index 0000000000000..3507fd80b288b
--- /dev/null
+++ b/test/builtins/Unit/clear_cache_test.c
@@ -0,0 +1,76 @@
+//===-- clear_cache_test.c - Test clear_cache -----------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+
+#include <stdio.h>
+#include <string.h>
+#include <stdint.h>
+#if defined(_WIN32)
+#include <windows.h>
+void __clear_cache(void* start, void* end)
+{
+    if (!FlushInstructionCache(GetCurrentProcess(), start, end-start))
+        exit(1);
+}
+#else
+#include <sys/mman.h>
+extern void __clear_cache(void* start, void* end);
+#endif
+
+
+
+
+typedef int (*pfunc)(void);
+
+int func1() 
+{
+    return 1;
+}
+
+int func2() 
+{
+    return 2;
+}
+
+
+
+unsigned char execution_buffer[128];
+
+int main()
+{
+    // make executable the page containing execution_buffer 
+    char* start = (char*)((uintptr_t)execution_buffer & (-4095));
+    char* end = (char*)((uintptr_t)(&execution_buffer[128+4096]) & (-4095));
+#if defined(_WIN32)
+    DWORD dummy_oldProt;
+    MEMORY_BASIC_INFORMATION b;
+    if (!VirtualQuery(start, &b, sizeof(b)))
+        return 1;
+    if (!VirtualProtect(b.BaseAddress, b.RegionSize, PAGE_EXECUTE_READWRITE, &b.Protect))
+#else
+    if (mprotect(start, end-start, PROT_READ|PROT_WRITE|PROT_EXEC) != 0)
+#endif
+        return 1;
+
+    // verify you can copy and execute a function
+    memcpy(execution_buffer, (void *)(uintptr_t)&func1, 128);
+    __clear_cache(execution_buffer, &execution_buffer[128]);
+    pfunc f1 = (pfunc)(uintptr_t)execution_buffer;
+    if ((*f1)() != 1)
+        return 1;
+
+    // verify you can overwrite a function with another
+    memcpy(execution_buffer, (void *)(uintptr_t)&func2, 128);
+    __clear_cache(execution_buffer, &execution_buffer[128]);
+    pfunc f2 = (pfunc)(uintptr_t)execution_buffer;
+    if ((*f2)() != 2)
+        return 1;
+
+    return 0;
+}