Allow multiple input domains to be run in the same benchmark program

Some math functions have distinct performance characteristics in
specific domains of inputs, where some inputs return via a fast path
while other inputs require multiple precision calculations, that too
at different precision levels.  The way to implement different domains
was to have a separate source file and benchmark definition, resulting
in separate programs.

This clutters up the benchmark, so this change allows these domains to
be consolidated into the same input file.  To do this, the input file
format is now enhanced to allow comments with a preceding # and
directives with two # at the begining of a line.  A directive that
looks like:

tells the benchmark generation script that what follows is a different
domain of inputs.  The value of the 'name' directive (in this case,
foo) is used in the output.  The two input domains are then executed
sequentially and their results collated separately.  with the above
directive, there would be two lines in the result that look like:

func(): ....
func(foo): ...

1 files changed, 91 insertions, 14 deletions

diff --git a/scripts/bench.pl b/scripts/bench.pl
index 5856cfa..dcc5ead 100755
--- a/scripts/bench.pl
+++ b/scripts/bench.pl
@@ -42,15 +42,28 @@ if (@ARGV == 3) {
 
 my $decl = "extern $ret $func (";
 
+# Function has no arguments.
 if (@args == 0 || $args[0] eq "void") {
   print "$decl void);\n";
-  print "#define CALL_BENCH_FUNC(j) $func();\n";
-  print "#define NUM_SAMPLES (1)\n";
+  print "#define CALL_BENCH_FUNC(i,j) $func();\n";
+  print "#define NUM_VARIANTS (1)\n";
+  print "#define NUM_SAMPLES(v) (1)\n";
+  print "#define VARIANT(v) FUNCNAME \"()\"\n"
 }
+# The function has arguments, so parse them and populate the inputs.
 else {
   my $num = 0;
-  my $bench_func = "#define CALL_BENCH_FUNC(j) $func (";
-  my $struct = "struct args {";
+  my $bench_func = "#define CALL_BENCH_FUNC(v, i) $func (";
+
+  my $struct =
+    "struct _variants
+    {
+      const char *name;
+      int count;
+      struct args *in;
+    };\n";
+
+  my $arg_struct = "struct args {";
 
   foreach $arg (@args) {
     if ($num > 0) {
@@ -58,24 +71,87 @@ else {
       $decl = "$decl,";
     }
 
-    $struct = "$struct $arg arg$num;";
-    $bench_func = "$bench_func in[j].arg$num";
+    $arg_struct = "$arg_struct $arg arg$num;";
+    $bench_func = "$bench_func variants[v].in[i].arg$num";
     $decl = "$decl $arg";
     $num = $num + 1;
   }
 
-  print "$decl);\n";
-  print "$bench_func);\n";
-  print "$struct } in[] = {";
+  $arg_struct = $arg_struct . "};\n";
+  $decl = $decl . ");\n";
+  $bench_func = $bench_func . ");\n";
+
+  # We create a hash of inputs for each variant of the test.
+  my $variant = "";
+  my @curvals;
+  my %vals;
 
   open INPUTS, "<$func-inputs" or die $!;
 
-  while (<INPUTS>) {
+  LINE:while (<INPUTS>) {
     chomp;
-    print "{$_},\n";
+
+    # New variant.
+    if (/^## (\w+): (\w+)/) {
+      #We only identify Name for now.
+      if ($1 ne "name") {
+        next LINE;
+      }
+
+      # Save values in the last variant.
+      my @copy = @curvals;
+      $vals{$variant} = \@copy;
+
+      # Prepare for the next.
+      $variant=$2;
+      undef @curvals;
+      next LINE;
+    }
+
+    # Skip over comments.
+    if (/^#/) {
+      next LINE;
+    }
+    push (@curvals, $_);
   }
-  print "};\n";
-  print "#define NUM_SAMPLES (sizeof (in) / sizeof (struct args))\n"
+
+  $vals{$variant} = \@curvals;
+
+  # Print the definitions and macros.
+  print $decl;
+  print $bench_func;
+  print $arg_struct;
+  print $struct;
+
+  my $c = 0;
+  my $key;
+
+  # Print the input arrays.
+  foreach $key (keys %vals) {
+    my @arr = @{$vals{$key}};
+
+    print "struct args in" . $c . "[" . @arr . "] = {\n";
+    foreach (@arr) {
+      print "{$_},\n";
+    }
+    print "};\n\n";
+    $c += 1;
+  }
+
+  # The variants.  Each variant then points to the appropriate input array we
+  # defined above.
+  print "struct _variants variants[" . (keys %vals) . "] = {\n";
+  $c = 0;
+  foreach $key (keys %vals) {
+    print "{\"$func($key)\", " . @{$vals{$key}} . ", in$c},\n";
+    $c += 1;
+  }
+  print "};\n\n";
+
+  # Finally, print the last set of macros.
+  print "#define NUM_VARIANTS $c\n";
+  print "#define NUM_SAMPLES(i) (variants[i].count)\n";
+  print "#define VARIANT(i) (variants[i].name)\n";
 }
 
 # In some cases not storing a return value seems to result in the function call
@@ -85,7 +161,8 @@ if ($ret ne "void") {
   $getret = "ret = ";
 }
 
-print "#define BENCH_FUNC(j) ({$getret CALL_BENCH_FUNC (j);})\n";
+# And we're done.
+print "#define BENCH_FUNC(i, j) ({$getret CALL_BENCH_FUNC (i, j);})\n";
 
 print "#define FUNCNAME \"$func\"\n";
 print "#include \"bench-skeleton.c\"\n";