On 19/07/17 22:02, Ian Tessier via newlib wrote:
> 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.
> ---
>  newlib/libc/machine/arm/strcpy.c | 13 +++++++------
>  1 file changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/newlib/libc/machine/arm/strcpy.c b/newlib/libc/machine/arm/strcpy.c
> index f1205b9c1..154451110 100644
> --- 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"
> 

This doesn't compile on ARMv4t - you've missed the "mov r3, r0"
instruction in the final hunk.

Fixed thusly (pushed).

-------------

ARMv4t does not support mov between two low registers.  Now we use
unified syntax mov instructions need converting to movs.
---
 newlib/libc/machine/arm/strcpy.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)