arm: Update strcpy.c to use UAL syntax.

With this change the arm platform can now be fully compiled with Clang.

Tested by comparing the output with GCC 4.8.2, and Clang 4.0, using a
variety of arches, big/little endianness, and arm/thumb mode to verify
the generated assembly output matches between GCC vs Clang with UAL, and
also GCC with UAL vs GCC with non-UAL, for all preprocessor code blocks.

The only difference found is an extra nop at the end of the function
when compiled with GCC using armv7-a/thumb/little-endian/-O2 compared to
Clang. The nop is not emitted when compiled in big-endian mode.

diff --git a/newlib/libc/machine/arm/strcpy.c b/newlib/libc/machine/arm/strcpy.c
index f1205b9c171716d891eafce83658360f4d8f3b63..154451110a79c18f576c1cfd7db847da2af4e8ee 100644 (file)
--- a/newlib/libc/machine/arm/strcpy.c
+++ b/newlib/libc/machine/arm/strcpy.c
@@ -42,6 +42,7 @@ char* __attribute__((naked))
 strcpy (char* dst, const char* src)
 {
   asm (
+      ".syntax unified\n\t"
 #if !(defined(__OPTIMIZE_SIZE__) || defined (PREFER_SIZE_OVER_SPEED) || \
       (defined (__thumb__) && !defined (__thumb2__)))
 #ifdef _ISA_ARM_7
@@ -127,15 +128,15 @@ strcpy (char* dst, const char* src)
 #ifdef __ARMEB__
        "tst    r2, #0xff00\n\t"
        "iteet  ne\n\t"
-       "strneh r2, [ip], #2\n\t"
+       "strhne r2, [ip], #2\n\t"
        "lsreq  r2, r2, #8\n\t"
-       "streqb r2, [ip]\n\t"
+       "strbeq r2, [ip]\n\t"
        "tstne  r2, #0xff\n\t"
 #else
        "tst    r2, #0xff\n\t"
        "itet   ne\n\t"
-       "strneh r2, [ip], #2\n\t"
-       "streqb r2, [ip]\n\t"
+       "strhne r2, [ip], #2\n\t"
+       "strbeq r2, [ip]\n\t"
        "tstne  r2, #0xff00\n\t"
 #endif
        "bne    5b\n\t"
@@ -162,9 +163,9 @@ strcpy (char* dst, const char* src)
        "mov    r3, r0\n\t"
   "1:\n\t"
        "ldrb   r2, [r1]\n\t"
-       "add    r1, r1, #1\n\t"
+       "adds   r1, #1\n\t"
        "strb   r2, [r3]\n\t"
-       "add    r3, r3, #1\n\t"
+       "adds   r3, #1\n\t"
        "cmp    r2, #0\n\t"
        "bne    1b\n\t"
        "bx     lr\n\t"