Add libc optimizations to bionic for MIPS

Test: Used bionic tests available under bionic/tests folder.
      Tested for mips32r1/mips32r2/mips64r6 on emulators.

Change-Id: I589415ddc496df3f6067ae34cb33ca58b3a1f276
Signed-off-by: Prashant Patil <prashant.patil@imgtec.com>
diff --git a/libc/arch-mips/string/strcpy.c b/libc/arch-mips/string/strcpy.c
new file mode 100644
index 0000000..7b5dee3
--- /dev/null
+++ b/libc/arch-mips/string/strcpy.c
@@ -0,0 +1,204 @@
+/*
+ * Copyright (c) 2017 Imagination Technologies.
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *      * Redistributions of source code must retain the above copyright
+ *        notice, this list of conditions and the following disclaimer.
+ *      * 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.
+ *      * Neither the name of Imagination Technologies 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 COPYRIGHT HOLDERS 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 COPYRIGHT
+ * OWNER 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>
+
+#define op_t        unsigned long int
+
+#if !defined(UNALIGNED_INSTR_SUPPORT)
+/* does target have unaligned lw/ld/ualw/uald instructions? */
+#define UNALIGNED_INSTR_SUPPORT 0
+#if __mips_isa_rev < 6 && !__mips1
+#undef UNALIGNED_INSTR_SUPPORT
+#define UNALIGNED_INSTR_SUPPORT 1
+#endif
+#endif
+
+#if !defined(HW_UNALIGNED_SUPPORT)
+/* Does target have hardware support for unaligned accesses?  */
+#define HW_UNALIGNED_SUPPORT 0
+#if __mips_isa_rev >= 6
+#undef HW_UNALIGNED_SUPPORT
+#define HW_UNALIGNED_SUPPORT 1
+#endif
+#endif
+
+#if __mips64
+typedef struct
+{
+  op_t B0:8, B1:8, B2:8, B3:8, B4:8, B5:8, B6:8, B7:8;
+} bits_t;
+#else
+typedef struct
+{
+  op_t B0:8, B1:8, B2:8, B3:8;
+} bits_t;
+#endif
+
+typedef union
+{
+  op_t v;
+  bits_t b;
+} bitfields_t;
+
+#if !HW_UNALIGNED_SUPPORT && UNALIGNED_INSTR_SUPPORT
+/* for MIPS GCC, there are no unaligned builtins - so this struct forces
+   the compiler to treat the pointer access as unaligned.  */
+struct ulw
+{
+  op_t uli;
+} __attribute__ ((packed));
+#endif /* !HW_UNALIGNED_SUPPORT && UNALIGNED_INSTR_SUPPORT */
+
+#define DO_BYTE(i, ptdst) {  \
+  *(ptdst+i) = a.b.B##i;     \
+  if(a.b.B##i == '\0')       \
+    return ret;              \
+}
+
+#if __mips64
+#define DO_BYTES(val, dst) {   \
+  bitfields_t a;               \
+  char *tdst = (char *)(dst);  \
+  a.v = val;                   \
+  DO_BYTE(0, tdst)             \
+  DO_BYTE(1, tdst)             \
+  DO_BYTE(2, tdst)             \
+  DO_BYTE(3, tdst)             \
+  DO_BYTE(4, tdst)             \
+  DO_BYTE(5, tdst)             \
+  DO_BYTE(6, tdst)             \
+  DO_BYTE(7, tdst)             \
+}
+#else
+#define DO_BYTES(val, dst) {   \
+  bitfields_t a;               \
+  char *tdst = (char *)(dst);  \
+  a.v = val;                   \
+  DO_BYTE(0, tdst)             \
+  DO_BYTE(1, tdst)             \
+  DO_BYTE(2, tdst)             \
+  DO_BYTE(3, tdst)             \
+}
+#endif
+
+#define DO_WORD_ALIGNED(dst, src) {                 \
+  op_t val = *(src);                                \
+  if ((((val - mask_1) & ~val) & mask_128) != 0) {  \
+    DO_BYTES(val, dst);                             \
+  } else *(dst) = val;                              \
+}
+
+#if !HW_UNALIGNED_SUPPORT
+#if UNALIGNED_INSTR_SUPPORT
+#define DO_WORD_UNALIGNED(dst, src) {               \
+  op_t val = *(src);                                \
+  if ((((val - mask_1) & ~val) & mask_128) != 0) {  \
+    DO_BYTES(val, dst);                             \
+  } else {                                          \
+    struct ulw *a = (struct ulw *)(dst);            \
+    a->uli = val;                                   \
+  }                                                 \
+}
+#else
+#define DO_WORD_UNALIGNED(dst, src) {                 \
+  op_t val = *(src);                                  \
+  if ((((val - mask_1) & ~val) & mask_128) != 0) {    \
+    DO_BYTES(val, dst);                               \
+  } else {                                            \
+    char *pdst = (char *) dst;                        \
+    const char *psrc = (const char *) src;            \
+    for (; (*pdst = *psrc) != '\0'; ++psrc, ++pdst);  \
+    return ret;                                       \
+  }                                                   \
+}
+#endif /* UNALIGNED_INSTR_SUPPORT */
+
+#define PROCESS_UNALIGNED_WORDS(a, b) { \
+  while (1) {                           \
+    DO_WORD_UNALIGNED(a, b);            \
+    DO_WORD_UNALIGNED(a + 1, b + 1);    \
+    DO_WORD_UNALIGNED(a + 2, b + 2);    \
+    DO_WORD_UNALIGNED(a + 3, b + 3);    \
+    a += 4;                             \
+    b += 4;                             \
+  }                                     \
+}
+#endif /* HW_UNALIGNED_SUPPORT */
+
+#define PROCESS_ALIGNED_WORDS(a, b) {  \
+  while (1) {                          \
+    DO_WORD_ALIGNED(a, b);             \
+    DO_WORD_ALIGNED(a + 1, b + 1);     \
+    DO_WORD_ALIGNED(a + 2, b + 2);     \
+    DO_WORD_ALIGNED(a + 3, b + 3);     \
+    a += 4;                            \
+    b += 4;                            \
+  }                                    \
+}
+
+char *
+strcpy (char *to, const char *from) __overloadable
+{
+  char *ret = to;
+  op_t mask_1, mask_128;
+  const op_t *src;
+  op_t *dst;
+
+  for (; (*to = *from) != '\0' && ((size_t) from % sizeof (op_t)) != 0; ++from, ++to);
+
+  if(*to != '\0') {
+    __asm__ volatile (
+      "li %0, 0x01010101 \n\t"
+      : "=r" (mask_1)
+    );
+#if __mips64
+    mask_1 |= mask_1 << 32;
+#endif
+    mask_128 = mask_1 << 7;
+
+    src = (const op_t *) from;
+    dst = (op_t *) to;
+
+#if HW_UNALIGNED_SUPPORT
+    PROCESS_ALIGNED_WORDS(dst, src);
+#else
+    if (((unsigned long) dst) % sizeof (op_t) == 0) {
+      PROCESS_ALIGNED_WORDS(dst, src);
+    } else {
+      PROCESS_UNALIGNED_WORDS(dst, src);
+    }
+#endif
+  }
+
+  return ret;
+}