Add systemtap markers to math function slow paths

Add systemtap probes to various slow paths in libm so that application
developers may use systemtap to find out if their applications are
hitting these slow paths.  We have added probes for pow, exp, log,
tan, atan and atan2.

1 files changed, 13 insertions, 1 deletions

diff --git a/sysdeps/ieee754/dbl-64/slowpow.c b/sysdeps/ieee754/dbl-64/slowpow.c
index a379728..d200c39 100644
--- a/sysdeps/ieee754/dbl-64/slowpow.c
+++ b/sysdeps/ieee754/dbl-64/slowpow.c
@@ -34,6 +34,8 @@
 #include "mpa.h"
 #include <math_private.h>
 
+#include <stap-probe.h>
+
 #ifndef SECTION
 # define SECTION
 #endif
@@ -97,7 +99,12 @@ __slowpow (double x, double y, double z)
   __sub (&mpp, &eps, &mpr1, p);
   __mp_dbl (&mpr1, &res1, p);
   if (res == res1)
-    return res;
+    {
+      /* Track how often we get to the slow pow code plus
+	 its input/output values.  */
+      LIBC_PROBE (slowpow_p10, 4, &x, &y, &z, &res);
+      return res;
+    }
 
   /* If we don't, then we repeat using a higher precision.  768 bits of
      precision ought to be enough for anybody.  */
@@ -109,5 +116,10 @@ __slowpow (double x, double y, double z)
   __mul (&mpy, &mpz, &mpw, p);
   __mpexp (&mpw, &mpp, p);
   __mp_dbl (&mpp, &res, p);
+
+  /* Track how often we get to the uber-slow pow code plus
+     its input/output values.  */
+  LIBC_PROBE (slowpow_p32, 4, &x, &y, &z, &res);
+
   return res;
 }