[tor-commits] [tor/master] In coverage builds, use branch-free timeradd() and timersub()

[dgoulet@xxxxxxxxxxxxxx]

commit b88281024579d5f207d15d1a2cc54c113f8a2bde
Author: Nick Mathewson <nickm@xxxxxxxxxxxxxx>
Date:   Wed May 15 08:28:25 2019 -0400

    In coverage builds, use branch-free timeradd() and timersub()
    
    The ordinary definitions of timeradd() and timersub() contain a
    branch. However, in coverage builds, this means that we get spurious
    complaints about partially covered basic blocks, in a way that makes
    our coverage determinism harder to check.
---
 src/lib/wallclock/timeval.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/src/lib/wallclock/timeval.h b/src/lib/wallclock/timeval.h
index 4967e939b..33076adc8 100644
--- a/src/lib/wallclock/timeval.h
+++ b/src/lib/wallclock/timeval.h
@@ -20,6 +20,27 @@
 #include <sys/time.h>
 #endif
 
+#ifdef TOR_COVERAGE
+/* For coverage builds, we use a slower definition of these macros without
+ * branches, to make coverage consistent. */
+#undef timeradd
+#undef timersub
+#define timeradd(tv1,tv2,tvout) \
+  do {                          \
+    (tvout)->tv_sec = (tv1)->tv_sec + (tv2)->tv_sec;    \
+    (tvout)->tv_usec = (tv1)->tv_usec + (tv2)->tv_usec; \
+    (tvout)->tv_sec += (tvout)->tv_usec / 1000000;      \
+    (tvout)->tv_usec %= 1000000;                        \
+  } while (0)
+#define timersub(tv1,tv2,tvout) \
+  do {                          \
+    (tvout)->tv_sec = (tv1)->tv_sec - (tv2)->tv_sec - 1;            \
+    (tvout)->tv_usec = (tv1)->tv_usec - (tv2)->tv_usec + 1000000;   \
+    (tvout)->tv_sec += (tvout)->tv_usec / 1000000;                  \
+    (tvout)->tv_usec %= 1000000;                                    \
+  } while (0)
+#endif
+
 #ifndef timeradd
 /** Replacement for timeradd on platforms that do not have it: sets tvout to
  * the sum of tv1 and tv2. */



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