[PATCH][benchtests] Accept output arguments to benchmark functions

[Siddhesh Poyarekar <siddhesh at redhat dot com>]

Hi,

This patch adds the ability to accept output arguments to functions
being benchmarked, by nesting the argument type in <> in the args
directive.  It includes the sincos implementation as an example, where
the function would have the following args directive:
    
This simply adds a definition for a static variable whose pointer gets
passed into the function, so it's not yet possible to pass something
more complicated like a pre-allocated string or array.  That would be
a good feature to add if a function needs it.

OK to commit?

Siddhesh

	* benchtests/README: Add note about output arguments.
	* benchtests/bench-sincos.c: Remove file.
	* benchtests/sincos-inputs: New file.
	* scripts/bench.pl: Identify output arguments and define
	static variables for them.

diff --git a/benchtests/README b/benchtests/README
index 0c643a6..a5fd8da 100644
--- a/benchtests/README
+++ b/benchtests/README
@@ -48,7 +48,8 @@ one to add `foo' to the bench tests:
 
   - args: This should be assigned a colon separated list of types of the input
     arguments.  This directive may be skipped if the function does not take any
-    inputs.
+    inputs.  One may identify output arguments by nesting them in <>.  The
+    generator will create variables to get outputs from the calling function.
   - ret: This should be assigned the type that the function returns.  This
     directive may be skipped if the function does not return a value.
   - includes: This should be assigned a comma-separated list of headers that
diff --git a/benchtests/bench-sincos.c b/benchtests/bench-sincos.c
deleted file mode 100644
index 7662dde..0000000
--- a/benchtests/bench-sincos.c
+++ /dev/null
@@ -1,86 +0,0 @@
-/* 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/>.  */
-
-extern void sincos (double, double *, double *);
-
-#define CALL_BENCH_FUNC(v, i, j, k) sincos ( variants[v].in[i].arg0, &j, &k);
-
-struct args
-{
-  volatile double arg0;
-};
-
-struct args in0[12] =
-{
-  { 0.9 },
-  { 2.3 },
-  { 3.7 },
-  { 3.9 },
-  { 4.0 },
-  { 4.7 },
-  { 5.9 },
-
-  { 0x1.000000cf4a2a1p0 },
-  { 0x1.0000010b239a8p0 },
-  { 0x1.00000162a932ap0 },
-  { 0x1.000002d452a11p0 },
-  { 0x1.000005bc7d86cp0 }
-};
-
-struct args in1[12] =
-{
-  { 0.93340582292648832662962377071381 },
-  { 2.3328432680770916363144351635128 },
-  { 3.7439477503636453548097051680088 },
-  { 3.9225160069792437411706487182528 },
-  { 4.0711651639931289992091478779912 },
-  { 4.7858438478542097982426639646292 },
-  { 5.9840767662578002727968851104379 },
-
-  { 0x1.000000cf4a2a2p0 },
-  { 0x1.0000010b239a9p0 },
-  { 0x1.00000162a932bp0 },
-  { 0x1.000002d452a10p0 },
-  { 0x1.000005bc7d86dp0 }
-};
-
-struct _variants
-{
-  const char *name;
-  int count;
-  struct args *in;
-};
-
-struct _variants variants[2] =
-  {
-    {"sincos()", 12, in0},
-    {"sincos(768bits)", 12, in1},
-  };
-
-#define NUM_VARIANTS 2
-#define NUM_SAMPLES(i) (variants[i].count)
-#define VARIANT(i) (variants[i].name)
-
-#define BENCH_FUNC(v, j) \
-({									      \
-  volatile double iptr;							      \
-  volatile double iptr2;						      \
-   CALL_BENCH_FUNC (v, j, iptr, iptr2);					      \
-})
-
-#define FUNCNAME "sincos"
-#include "bench-skeleton.c"
diff --git a/benchtests/sincos-inputs b/benchtests/sincos-inputs
new file mode 100644
index 0000000..3df4d2a
--- /dev/null
+++ b/benchtests/sincos-inputs
@@ -0,0 +1,27 @@
+## includes: math.h
+## args: double:<double *>:<double *>
+0.9
+2.3
+3.7
+3.9
+4.0
+4.7
+5.9
+0x1.000000cf4a2a1p0
+0x1.0000010b239a8p0
+0x1.00000162a932ap0
+0x1.000002d452a11p0
+0x1.000005bc7d86cp0
+## name: 768bits
+0.93340582292648832662962377071381
+2.3328432680770916363144351635128
+3.7439477503636453548097051680088
+3.9225160069792437411706487182528
+4.0711651639931289992091478779912
+4.7858438478542097982426639646292
+5.9840767662578002727968851104379
+0x1.000000cf4a2a2p0
+0x1.0000010b239a9p0
+0x1.00000162a932bp0
+0x1.000002d452a10p0
+0x1.000005bc7d86dp0
diff --git a/scripts/bench.pl b/scripts/bench.pl
index 492ab81..7eb1525 100755
--- a/scripts/bench.pl
+++ b/scripts/bench.pl
@@ -93,6 +93,13 @@ LINE:while (<INPUTS>) {
 
 my $bench_func = "#define CALL_BENCH_FUNC(v, i) $func (";
 
+# Output variables.  These include the return value as well as any pointers
+# that may get passed into the function, denoted by the <> around the type.
+my $outvars = "";
+
+if ($ret ne "void") {
+  $outvars = "static volatile $ret ret;\n";
+}
 
 # Print the definitions and macros.
 foreach $incl (@include_headers) {
@@ -124,8 +131,18 @@ if (@args > 0) {
       $bench_func = "$bench_func,";
     }
 
-    $arg_struct = "$arg_struct volatile $arg arg$num;";
-    $bench_func = "$bench_func variants[v].in[i].arg$num";
+    $_ = $arg;
+    if (/<(.*)\*>/) {
+      # Output variables.  These have to be pointers, so dereference once by
+      # dropping one *.
+      $outvars = $outvars . "static $1 out$num;\n";
+      $bench_func = "$bench_func &out$num";
+    }
+    else {
+      $arg_struct = "$arg_struct volatile $arg arg$num;";
+      $bench_func = "$bench_func variants[v].in[i].arg$num";
+    }
+
     $num = $num + 1;
   }
 
@@ -172,12 +189,12 @@ else {
   print "#define VARIANT(v) FUNCNAME \"()\"\n"
 }
 
-
+# Print the output variable definitions.
+print "$outvars\n";
 
 # In some cases not storing a return value seems to result in the function call
 # being optimized out.
 if ($ret ne "void") {
-  print "static volatile $ret ret;\n";
   $getret = "ret = ";
 }