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authormarkm <markm@FreeBSD.org>1999-05-02 14:33:17 +0000
committermarkm <markm@FreeBSD.org>1999-05-02 14:33:17 +0000
commit77644ee620b6a79cf8c538abaf7cd301a875528d (patch)
treeb4adabf341898a4378f4b7f8c7fb65f3f7c77769 /contrib/perl5/t/op/repeat.t
parent4fcbc3669aa997848e15198cc9fb856287a6788c (diff)
downloadFreeBSD-src-77644ee620b6a79cf8c538abaf7cd301a875528d.zip
FreeBSD-src-77644ee620b6a79cf8c538abaf7cd301a875528d.tar.gz
Maintenance releace 3 of perl5.005. Includes support for threads.
Diffstat (limited to 'contrib/perl5/t/op/repeat.t')
-rwxr-xr-xcontrib/perl5/t/op/repeat.t53
1 files changed, 52 insertions, 1 deletions
diff --git a/contrib/perl5/t/op/repeat.t b/contrib/perl5/t/op/repeat.t
index 54fa590..f935bf1 100755
--- a/contrib/perl5/t/op/repeat.t
+++ b/contrib/perl5/t/op/repeat.t
@@ -2,7 +2,7 @@
# $RCSfile: repeat.t,v $$Revision: 4.1 $$Date: 92/08/07 18:28:21 $
-print "1..19\n";
+print "1..20\n";
# compile time
@@ -40,3 +40,54 @@ print join(':', () x 4) eq '' ? "ok 16\n" : "not ok 16\n";
print join(':', (9) x 4) eq '9:9:9:9' ? "ok 17\n" : "not ok 17\n";
print join(':', (9,9) x 4) eq '9:9:9:9:9:9:9:9' ? "ok 18\n" : "not ok 18\n";
print join('', (split(//,"123")) x 2) eq '123123' ? "ok 19\n" : "not ok 19\n";
+
+#
+# The test #20 is actually testing for Digital C compiler optimizer bug.
+#
+# Dec C versions 5.* and 6.0 (used in Digital UNIX and VMS) used
+# to produce (as of December 1998) broken code for util.c:repeatcpy()
+# (a utility function for the 'x' operator) in the case *all* these
+# four conditions held:
+#
+# (1) len == 1
+# (2) "from" had the 8th bit on in its single character
+# (3) count > 7 (the 'x' count > 16)
+# (4) the highest optimization level was used in compilation
+# (which is the default when compiling Perl)
+#
+# The bug looked like this (. being the eight-bit character and ? being \xff):
+#
+# 16 ................
+# 17 .........???????.
+# 18 .........???????..
+# 19 .........???????...
+# 20 .........???????....
+# 21 .........???????.....
+# 22 .........???????......
+# 23 .........???????.......
+# 24 .........???????.???????
+# 25 .........???????.???????.
+#
+# The bug could be (obscurely) avoided by changing "from" to
+# be an unsigned char pointer.
+#
+# The bug was triggered in the "if (len == 1)" branch. The fix
+# was to introduce a new temporary variable. In diff -u format:
+#
+# register char *frombase = from;
+#
+# if (len == 1) {
+#- todo = *from;
+#+ register char c = *from;
+# while (count-- > 0)
+#- *to++ = todo;
+#+ *to++ = c;
+# return;
+# }
+#
+# This obscure bug was not found by the then test suite but instead
+# by Mark.Martinec@nsc.ijs.si while trying to install Digest-MD5-2.00.
+#
+# jhi@iki.fi
+#
+print "\xdd" x 24 eq "\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd\xdd" ? "ok 20\n" : "not ok 20\n";
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