From: "Ian Tessier via newlib" <newlib@sourceware.org>
To: newlib@sourceware.org
Cc: Ian Tessier <itessier@google.com>
Subject: [PATCH] arm: Update strcpy.c to use UAL syntax.
Date: Wed, 19 Jul 2017 21:02:00 -0000 [thread overview]
Message-ID: <20170719210243.8975-1-itessier@google.com> (raw)
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"
--
2.14.0.rc0.284.gd933b75aa4-goog
next reply other threads:[~2017-07-19 21:02 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-19 21:02 Ian Tessier via newlib [this message]
2017-07-20 14:19 ` Corinna Vinschen
2017-07-21 10:21 ` Richard Earnshaw (lists)
[not found] ` <CAP235ST1nYzhCDsyzE7A6NXjP2hg_sy=4bjzD_3OCXQerLYmnA@mail.gmail.com>
2017-07-21 21:13 ` Ian Tessier via newlib
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