test: blitters-test-bisect.rb converted to perl

This new script can be used to run continuously to compare two test
programs based on fuzzer_test_main() function from 'util.c' and
narrow down to a single problematic test from the batch which results
in different behavior.

diff --git a/test/fuzzer-find-diff.pl b/test/fuzzer-find-diff.pl
new file mode 100644 (file)
index 0000000..53d9b8d
--- /dev/null
+++ b/test/fuzzer-find-diff.pl
@@ -0,0 +1,68 @@
+#!/usr/bin/env perl
+
+$usage = "Usage:
+  fuzzer-find-diff.pl reference_binary new_binary [number_of_tests_to_run]
+
+The first two input arguments are the commands to run the test programs
+based on fuzzer_test_main() function from 'util.c' (preferably they should
+be statically compiled, this can be achieved via '--disable-shared' pixman
+configure option). The third optional argument is the number of test rounds
+to run (if not specified, then testing runs infinitely or until some problem
+is detected).
+
+Usage examples:
+  fuzzer-find-diff.pl ./blitters-test-with-sse-disabled ./blitters-test 9000000
+  fuzzer-find-diff.pl ./blitters-test \"ssh ppc64_host /path/to/blitters-test\"
+";
+
+$#ARGV >= 1 or die $usage;
+
+$batch_size = 10000;
+
+if ($#ARGV >= 2) {
+    $number_of_tests = int($ARGV[2]);
+} else {
+    $number_of_tests = -1
+}
+
+sub test_range {
+    my $min = shift;
+    my $max = shift;
+
+    if (`$ARGV[0] $min $max 2>/dev/null` eq `$ARGV[1] $min $max 2>/dev/null`) {
+        return;
+    }
+
+    while ($max != $min + 1) {
+        my $avg = int(($min + $max) / 2);
+        my $res1 = `$ARGV[0] $min $avg 2>/dev/null`;
+        my $res2 = `$ARGV[1] $min $avg 2>/dev/null`;
+        if ($res1 ne $res2) {
+            $max = $avg;
+        } else {
+            $min = $avg;
+        }
+    }
+    return $max;
+}
+
+$base = 1;
+while ($number_of_tests <= 0 || $base <= $number_of_tests) {
+    printf("testing %-12d\r", $base + $batch_size - 1);
+    my $res = test_range($base, $base + $batch_size - 1);
+    if ($res) {
+        printf("Failure: results are different for test %d:\n", $res);
+
+        printf("\n-- ref --\n");
+        print `$ARGV[0] $res`;
+        printf("-- new --\n");
+        print `$ARGV[1] $res`;
+
+        printf("The problematic conditions can be reproduced by running:\n");
+        printf("$ARGV[1] %d\n", $res);
+
+        exit(1);
+    }
+    $base += $batch_size;
+}
+printf("Success: %d tests finished\n", $base - 1);