[PATCH] Separate benchmarks for fast and slow paths of pow and exp

[Siddhesh Poyarekar <siddhesh at redhat dot com>]

Hi,

This patch uses the earlier Rules tweak to separate the benchmark
results for fast and slow paths of exp and pow since those results
don't make sense together.  The patch also adjusts the number of
iterations to make each benchmark last ~10 sec (give or take a couple
of seconds) on my system.  Mileage may vary on other systems, but the
idea is to make the number of iterations high enough and roughly
comparable.

Here's an example benchmark output on my Fedora 17 on core i7:

exp: ITERS:5e+08: TOTAL:11.6213s, MAX:102.573ns, MIN:16.316ns, 4.30245e+07 iter/s
pow: ITERS:2e+08: TOTAL:12.1205s, MAX:187.642ns, MIN:58.18ns, 1.65009e+07 iter/s
slowexp: ITERS:5e+06: TOTAL:8.81398s, MAX:3189.31ns, MIN:1726.46ns, 567281 iter/s
slowpow: ITERS:100000: TOTAL:8.48876s, MAX:88725.7ns, MIN:83907.3ns, 11780.3 iter/s

Siddhesh

	* benchtests/Makefile: Add benchmarks for slowpow and slowexp.
	(bench): Add slowexp and slowpow.
	(exp-ITER): Increase iterations.
	(pow-ITER): Likewise.
	* benchtests/exp-inputs: Change input.
	* benchtests/pow-inputs: Likewise.
	* benchtests/slowexp-inputs: New file.
	* benchtests/slowexp.c: New file.
	* benchtests/slowpow-inputs: New file.
	* benchtests/slowpow.c: New file.

diff --git a/benchtests/Makefile b/benchtests/Makefile
index 74938b9..f301ed1 100644
--- a/benchtests/Makefile
+++ b/benchtests/Makefile
@@ -43,17 +43,33 @@
 #   See pow-inputs for an example.
 
 subdir := benchtests
-bench := exp pow
+bench := exp pow slowexp slowpow
 
-exp-ITER = 100000
+# exp function fast path
+exp-ITER = 5e8
 exp-ARGLIST = double
 exp-RET = double
 LDFLAGS-bench-exp = -lm
 
-pow-ITER = 100000
+# pow function fast path
+pow-ITER = 2e8
 pow-ARGLIST = double:double
 pow-RET = double
 LDFLAGS-bench-pow = -lm
 
+# exp function slowest path
+slowexp-ITER = 5e6
+slowexp-ARGLIST = double
+slowexp-RET = double
+slowexp-INCLUDE = slowexp.c
+LDFLAGS-bench-slowexp = -lm
+
+# pow function slowest path
+slowpow-ITER = 1e5
+slowpow-ARGLIST = double:double
+slowpow-RET = double
+slowpow-INCLUDE = slowpow.c
+LDFLAGS-bench-slowpow = -lm
+
 include ../Makeconfig
 include ../Rules
diff --git a/benchtests/exp-inputs b/benchtests/exp-inputs
index a2086ba..d81cc07 100644
--- a/benchtests/exp-inputs
+++ b/benchtests/exp-inputs
@@ -1 +1 @@
-708.00096423260981737257679924368858
+42
diff --git a/benchtests/pow-inputs b/benchtests/pow-inputs
index dbb1270..2f7cc03 100644
--- a/benchtests/pow-inputs
+++ b/benchtests/pow-inputs
@@ -1 +1 @@
-1.0000000000000020, 1.5
+42.0, 42.0
diff --git a/benchtests/slowexp-inputs b/benchtests/slowexp-inputs
new file mode 100644
index 0000000..a2086ba
--- /dev/null
+++ b/benchtests/slowexp-inputs
@@ -0,0 +1 @@
+708.00096423260981737257679924368858
diff --git a/benchtests/slowexp.c b/benchtests/slowexp.c
new file mode 100644
index 0000000..92ac5e9
--- /dev/null
+++ b/benchtests/slowexp.c
@@ -0,0 +1,19 @@
+/* Define slowexp.
+   Copyright (C) 2013 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#define slowexp exp
diff --git a/benchtests/slowpow-inputs b/benchtests/slowpow-inputs
new file mode 100644
index 0000000..dbb1270
--- /dev/null
+++ b/benchtests/slowpow-inputs
@@ -0,0 +1 @@
+1.0000000000000020, 1.5
diff --git a/benchtests/slowpow.c b/benchtests/slowpow.c
new file mode 100644
index 0000000..08f436d
--- /dev/null
+++ b/benchtests/slowpow.c
@@ -0,0 +1,19 @@
+/* Define slowpow.
+   Copyright (C) 2013 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#define slowpow pow