benching: add benching facilities

include/libunwind-common.h.in

@@ -255,3 +255,10 @@ extern const char *unw_strerror (int);
 extern int unw_backtrace (void **, int);
 
 extern unw_addr_space_t unw_local_addr_space;
+
+#include <time.h>
+
+struct timespec chrono_report(void);
+struct timespec chrono_start(void);
+void chrono_end(struct timespec);
+void chrono_report_disp(void);

src/Makefile.am

@@ -95,6 +95,11 @@ noinst_HEADERS				+= setjmp/setjmp_i.h
 ### libunwind:
 libunwind_la_LIBADD =
 
+### libunwind-benchmarking
+libunwind_benchmarking_la_SOURCES = benchmarking.c
+noinst_LTLIBRARIES += libunwind-benchmarking.la
+libunwind_la_LIBADD += libunwind-benchmarking.la
+
 # List of arch-independent files needed by both local-only and generic
 # libraries:
 libunwind_la_SOURCES_common =					\

src/benchmarking.c

@@ -0,0 +1,75 @@
+/********** Libunwind -- eh_elf flavour **********
+ * This is the eh_elf version of libunwind, made for academic purposes.
+ *
+ * Théophile Bastian <theophile.bastian@ens.fr> <contact+github@tobast.fr>
+ *************************************************
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ ************************************************/
+
+#include <time.h>
+#include <stdint.h>
+#include <stdio.h>
+
+typedef struct timespec chrono_t;
+
+static const long NSEC_MAX = 1000 * 1000 * 1000;
+static chrono_t _timer_accu = {
+    .tv_sec = 0,
+    .tv_nsec = 0
+};
+static size_t _call_count = 0;
+
+static void normalize_timer(chrono_t* timer) {
+    if(timer->tv_nsec >= NSEC_MAX) {
+        timer->tv_sec++;
+        timer->tv_nsec -= NSEC_MAX;
+    }
+    else if(timer->tv_nsec < 0) {
+        timer->tv_sec--;
+        timer->tv_nsec += NSEC_MAX;
+    }
+}
+
+static void timer_add(chrono_t* out, chrono_t t1, chrono_t t2) {
+    out->tv_sec = t1.tv_sec + t2.tv_sec;
+    out->tv_nsec = t1.tv_nsec + t2.tv_nsec;
+    normalize_timer(out);
+}
+
+static void timer_diff(chrono_t* out, chrono_t t1, chrono_t t2) {
+    out->tv_sec = t2.tv_sec - t1.tv_sec;
+    out->tv_nsec = t2.tv_nsec - t1.tv_nsec;
+    normalize_timer(out);
+}
+
+chrono_t chrono_start() {
+    chrono_t out;
+    clock_gettime(CLOCK_REALTIME, &out);
+    return out;
+}
+
+void chrono_end(chrono_t start) {
+    chrono_t diff;
+    ++_call_count;
+    timer_diff(&diff, start, chrono_start());
+    timer_add(&_timer_accu, _timer_accu, diff);
+}
+
+chrono_t chrono_report() {
+    return _timer_accu;
+}
+
+void chrono_report_disp() {
+    fprintf(stderr,
+            "=============== BENCH ===============\n"
+            "Total unwind time: %ld s %ld ns, %lu calls\n",
+            _timer_accu.tv_sec,
+            _timer_accu.tv_nsec,
+            _call_count);
+}