Add weak definitions of trace-cmp hooks to dfsan

Summary:
This allows to build and link the code with e.g.
-fsanitize=dataflow -fsanitize-coverage=trace-pc-guard,pc-table,func,trace-cmp
w/o providing (all) the definitions of trace-cmp hooks.

This is similar to dummy hooks provided by asan/ubsan/msan for the same purpose,
except that some of the hooks need to have the __dfsw_ prefix
since we need dfsan to replace them.

Reviewers: pcc

Reviewed By: pcc

Subscribers: delcypher, #sanitizers, llvm-commits

Differential Revision: https://reviews.llvm.org/D47605

llvm-svn: 333796

1 files changed, 50 insertions, 0 deletions

diff --git a/compiler-rt/test/dfsan/trace-cmp.c b/compiler-rt/test/dfsan/trace-cmp.c
new file mode 100644
index 00000000000..0645363b260
--- /dev/null
+++ b/compiler-rt/test/dfsan/trace-cmp.c
@@ -0,0 +1,50 @@
+// Checks that dfsan works with trace-cmp instrumentation, even if some hooks
+// are not defined (relies on week hooks implemented in dfsan).
+//
+// RUN: %clang_dfsan -fsanitize-coverage=trace-pc-guard,pc-table,func,trace-cmp %s -o %t
+// RUN: %run %t 2>&1 | FileCheck %s
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include <sanitizer/dfsan_interface.h>
+
+uint32_t a4, b4;
+uint64_t a8, b8;
+
+// Define just two hooks, and leave others undefined.
+void __dfsw___sanitizer_cov_trace_const_cmp4(uint8_t a, uint8_t b,
+                                             dfsan_label l1, dfsan_label l2) {
+  printf("const_cmp4 %d %d\n", a, b);
+}
+void __dfsw___sanitizer_cov_trace_cmp8(uint8_t a, uint8_t b, dfsan_label l1,
+                                       dfsan_label l2) {
+  printf("cmp8 %d %d\n", a, b);
+}
+
+int main(int argc, char **argv) {
+  printf("MAIN\n");
+  // CHECK: MAIN
+
+  if (a4 != b4) abort();
+  if (a4 == 42) abort();
+  // CHECK: const_cmp4 42 0
+  if (a8 != b8) abort();
+  // CHECK: cmp8 0 0
+  if (a8 == 66) abort();
+
+  switch (10 / (a4 + 2)) {
+    case 1: abort();
+    case 2: exit(1);
+    case 5:
+            printf("SWITCH OK\n");
+            break;
+  }
+  // CHECK: SWITCH OK
+
+
+  printf("DONE\n");
+  // CHECK: DONE
+  return 0;
+}