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.

6 files changed, 45 insertions, 5 deletions

diff --git a/sysdeps/ieee754/dbl-64/e_atan2.c b/sysdeps/ieee754/dbl-64/e_atan2.c
index 4ebe9c0..4075622 100644
--- a/sysdeps/ieee754/dbl-64/e_atan2.c
+++ b/sysdeps/ieee754/dbl-64/e_atan2.c
@@ -42,6 +42,7 @@
 #include "uatan.tbl"
 #include "atnat2.h"
 #include <math_private.h>
+#include <stap-probe.h>
 
 #ifndef SECTION
 # define SECTION
@@ -597,7 +598,11 @@ atan2Mp (double x, double y, const int pr[])
       __mp_dbl (&mpz1, &z1, p);
       __mp_dbl (&mpz2, &z2, p);
       if (z1 == z2)
-	return z1;
+	{
+	  LIBC_PROBE (slowatan2, 4, &p, &x, &y, &z1);
+	  return z1;
+	}
     }
+  LIBC_PROBE (slowatan2_inexact, 4, &p, &x, &y, &z1);
   return z1;			/*if impossible to do exact computing */
 }
diff --git a/sysdeps/ieee754/dbl-64/e_log.c b/sysdeps/ieee754/dbl-64/e_log.c
index f9300f9..17ab75a 100644
--- a/sysdeps/ieee754/dbl-64/e_log.c
+++ b/sysdeps/ieee754/dbl-64/e_log.c
@@ -39,6 +39,7 @@
 #include "mpa.h"
 #include "MathLib.h"
 #include <math_private.h>
+#include <stap-probe.h>
 
 #ifndef SECTION
 # define SECTION
@@ -242,8 +243,12 @@ stage_n:
       __mp_dbl (&mpy1, &y1, p);
       __mp_dbl (&mpy2, &y2, p);
       if (y1 == y2)
-	return y1;
+	{
+	  LIBC_PROBE (slowlog, 3, &p, &x, &y1);
+	  return y1;
+	}
     }
+  LIBC_PROBE (slowlog_inexact, 3, &p, &x, &y1);
   return y1;
 }
 
diff --git a/sysdeps/ieee754/dbl-64/s_atan.c b/sysdeps/ieee754/dbl-64/s_atan.c
index 7b6c83f..35ab5c1 100644
--- a/sysdeps/ieee754/dbl-64/s_atan.c
+++ b/sysdeps/ieee754/dbl-64/s_atan.c
@@ -42,6 +42,7 @@
 #include "uatan.tbl"
 #include "atnat.h"
 #include <math.h>
+#include <stap-probe.h>
 
 void __mpatan (mp_no *, mp_no *, int);	/* see definition in mpatan.c */
 static double atanMp (double, const int[]);
@@ -306,8 +307,12 @@ atanMp (double x, const int pr[])
       __mp_dbl (&mpy1, &y1, p);
       __mp_dbl (&mpy2, &y2, p);
       if (y1 == y2)
-	return y1;
+	{
+	  LIBC_PROBE (slowatan, 3, &p, &x, &y1);
+	  return y1;
+	}
     }
+  LIBC_PROBE (slowatan_inexact, 3, &p, &x, &y1);
   return y1;			/*if impossible to do exact computing */
 }
 
diff --git a/sysdeps/ieee754/dbl-64/s_tan.c b/sysdeps/ieee754/dbl-64/s_tan.c
index 54f863e..cc0dbbb 100644
--- a/sysdeps/ieee754/dbl-64/s_tan.c
+++ b/sysdeps/ieee754/dbl-64/s_tan.c
@@ -41,6 +41,7 @@
 #include <math.h>
 #include <math_private.h>
 #include <fenv.h>
+#include <stap-probe.h>
 
 #ifndef SECTION
 # define SECTION
@@ -838,6 +839,7 @@ tanMp (double x)
   p = 32;
   __mptan (x, &mpy, p);
   __mp_dbl (&mpy, &y, p);
+  LIBC_PROBE (slowtan, 2, &x, &y);
   return y;
 }
 
diff --git a/sysdeps/ieee754/dbl-64/slowexp.c b/sysdeps/ieee754/dbl-64/slowexp.c
index 8f353f6..525224f 100644
--- a/sysdeps/ieee754/dbl-64/slowexp.c
+++ b/sysdeps/ieee754/dbl-64/slowexp.c
@@ -29,6 +29,8 @@
 /**************************************************************************/
 #include <math_private.h>
 
+#include <stap-probe.h>
+
 #ifndef USE_LONG_DOUBLE_FOR_MP
 # include "mpa.h"
 void __mpexp (mp_no *x, mp_no *y, int p);
@@ -60,13 +62,22 @@ __slowexp (double x)
   __mp_dbl (&mpw, &w, p);
   __mp_dbl (&mpz, &z, p);
   if (w == z)
-    return w;
+    {
+      /* Track how often we get to the slow exp code plus
+	 its input/output values.  */
+      LIBC_PROBE (slowexp_p6, 2, &x, &w);
+      return w;
+    }
   else
     {
       p = 32;
       __dbl_mp (x, &mpx, p);
       __mpexp (&mpx, &mpy, p);
       __mp_dbl (&mpy, &res, p);
+
+      /* Track how often we get to the uber-slow exp code plus
+	 its input/output values.  */
+      LIBC_PROBE (slowexp_p32, 2, &x, &res);
       return res;
     }
 #else
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;
 }