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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.
This commit is contained in:
Ian Tessier via newlib 2017-07-19 14:02:43 -07:00 committed by Corinna Vinschen
parent d2ae2f00b8
commit 4bce7ecbe1
1 changed files with 7 additions and 6 deletions
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13
newlib/libc/machine/arm/strcpy.c
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@ -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"