tsan: add benchmark that allows to investigate shadow memory consumption

llvm-svn: 206578

compiler-rt/test/tsan/bench_shadow_flush.cc

@@ -0,0 +1,42 @@
+// RUN: %clangxx_tsan %s -o %t
+// RUN: %t 2>&1 | FileCheck %s
+
+#include <pthread.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <time.h>
+#include <sys/mman.h>
+
+const long kSmallPage = 4 << 10;
+const long kLargePage = 2 << 20;
+
+typedef unsigned long uptr;
+
+int main(int argc, const char **argv) {
+  uptr mem_size = 4 << 20;
+  if (argc > 1)
+    mem_size = (uptr)atoi(argv[1]) << 20;
+  uptr stride = kSmallPage;
+  if (argc > 2)
+    stride = (uptr)atoi(argv[2]) << 10;
+  int niter = 1;
+  if (argc > 3)
+    niter = atoi(argv[3]);
+
+  void *p = mmap(0, mem_size + kLargePage, PROT_READ | PROT_WRITE,
+      MAP_ANON | MAP_PRIVATE, -1, 0);
+  uptr a = ((uptr)p + kLargePage - 1) & ~(kLargePage - 1);
+  volatile char *mem = (volatile char *)a;
+
+  for (int i = 0; i < niter; i++) {
+    for (uptr off = 0; off < mem_size; off += stride)
+      mem[off] = 42;
+  }
+
+  fprintf(stderr, "DONE\n");
+}
+
+// CHECK: DONE
+