Optimize __memset_chk, __memcpy_chk. DO NOT MERGE.

This change creates assembler versions of __memcpy_chk/__memset_chk
that is implemented in the memcpy/memset assembler code. This change
avoids an extra call to memcpy/memset, instead allowing a simple fall
through to occur from the chk code into the body of the real
implementation.

Testing:

- Ran the libc_test on __memcpy_chk/__memset_chk on all nexus devices.
- Wrote a small test executable that has three calls to __memcpy_chk and
  three calls to __memset_chk. First call dest_len is length + 1. Second
  call dest_len is length. Third call dest_len is length - 1.
  Verified that the first two calls pass, and the third fails. Examined
  the logcat output on all nexus devices to verify that the fortify
  error message was sent properly.
- I benchmarked the new __memcpy_chk and __memset_chk on all systems. For
  __memcpy_chk and large copies, the savings is relatively small (about 1%).
  For small copies, the savings is large on cortex-a15/krait devices
  (between 5% to 30%).
  For cortex-a9 and small copies, the speed up is present, but relatively
  small (about 3% to 5%).
  For __memset_chk and large copies, the savings is also small (about 1%).
  However, all processors show larger speed-ups on small copies (about 30% to
  100%).

Bug: 9293744

Merge from internal master.

(cherry-picked from 7c860db0747f6276a6e43984d43f8fa5181ea936)

Change-Id: I916ad305e4001269460ca6ebd38aaa0be8ac7f52

1 files changed, 47 insertions, 0 deletions

diff --git a/libc/bionic/__strrchr_chk.cpp b/libc/bionic/__strrchr_chk.cpp
new file mode 100644
index 000000000..14100f791
--- /dev/null
+++ b/libc/bionic/__strrchr_chk.cpp
@@ -0,0 +1,47 @@
+/*	$OpenBSD: rindex.c,v 1.6 2005/08/08 08:05:37 espie Exp $ */
+/*
+ * Copyright (c) 1988 Regents of the University of California.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <string.h>
+#include "libc_logging.h"
+
+extern "C" char* __strrchr_chk(const char *p, int ch, size_t s_len)
+{
+    char *save;
+
+    for (save = NULL;; ++p, s_len--) {
+        if (s_len == 0)
+            __fortify_chk_fail("strrchr read beyond buffer", 0);
+        if (*p == (char) ch)
+            save = (char *)p;
+        if (!*p)
+            return(save);
+    }
+    /* NOTREACHED */
+}