* [PATCH] arm: Update strcpy.c to use UAL syntax. @ 2017-07-19 21:02 Ian Tessier via newlib 2017-07-20 14:19 ` Corinna Vinschen 2017-07-21 10:21 ` Richard Earnshaw (lists) 0 siblings, 2 replies; 4+ messages in thread From: Ian Tessier via newlib @ 2017-07-19 21:02 UTC (permalink / raw) To: newlib; +Cc: Ian Tessier 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 ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] arm: Update strcpy.c to use UAL syntax. 2017-07-19 21:02 [PATCH] arm: Update strcpy.c to use UAL syntax Ian Tessier via newlib @ 2017-07-20 14:19 ` Corinna Vinschen 2017-07-21 10:21 ` Richard Earnshaw (lists) 1 sibling, 0 replies; 4+ messages in thread From: Corinna Vinschen @ 2017-07-20 14:19 UTC (permalink / raw) To: newlib [-- Attachment #1: Type: text/plain, Size: 2380 bytes --] On Jul 19 14:02, 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" > -- > 2.14.0.rc0.284.gd933b75aa4-goog Pushed. Thanks, Corinna -- Corinna Vinschen Cygwin Maintainer Red Hat [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 819 bytes --] ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] arm: Update strcpy.c to use UAL syntax. 2017-07-19 21:02 [PATCH] arm: Update strcpy.c to use UAL syntax Ian Tessier via newlib 2017-07-20 14:19 ` Corinna Vinschen @ 2017-07-21 10:21 ` Richard Earnshaw (lists) [not found] ` <CAP235ST1nYzhCDsyzE7A6NXjP2hg_sy=4bjzD_3OCXQerLYmnA@mail.gmail.com> 1 sibling, 1 reply; 4+ messages in thread From: Richard Earnshaw (lists) @ 2017-07-21 10:21 UTC (permalink / raw) To: Ian Tessier, newlib [-- Attachment #1: Type: text/plain, Size: 2552 bytes --] 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(-) [-- Attachment #2: strcpy.patch --] [-- Type: text/x-patch, Size: 410 bytes --] diff --git a/newlib/libc/machine/arm/strcpy.c b/newlib/libc/machine/arm/strcpy.c index 1544511..111528e 100644 --- a/newlib/libc/machine/arm/strcpy.c +++ b/newlib/libc/machine/arm/strcpy.c @@ -160,7 +160,7 @@ strcpy (char* dst, const char* src) "bne 1b\n\t" "bx lr\n\t" #else - "mov r3, r0\n\t" + "movs r3, r0\n\t" "1:\n\t" "ldrb r2, [r1]\n\t" "adds r1, #1\n\t" ^ permalink raw reply [flat|nested] 4+ messages in thread
[parent not found: <CAP235ST1nYzhCDsyzE7A6NXjP2hg_sy=4bjzD_3OCXQerLYmnA@mail.gmail.com>]
* Re: [PATCH] arm: Update strcpy.c to use UAL syntax. [not found] ` <CAP235ST1nYzhCDsyzE7A6NXjP2hg_sy=4bjzD_3OCXQerLYmnA@mail.gmail.com> @ 2017-07-21 21:13 ` Ian Tessier via newlib 0 siblings, 0 replies; 4+ messages in thread From: Ian Tessier via newlib @ 2017-07-21 21:13 UTC (permalink / raw) To: Richard Earnshaw (lists); +Cc: newlib Oops, I did indeed leave out armv(4|5)t. Thanks for fixing it. Interestingly, with the non-UAL version of strcpy.c the mov instruction gets emitted as "adds r3, r0, #0", while in UAL (both gcc/clang) it's emitted as "movs r3, r0". On Fri, Jul 21, 2017 at 2:11 PM, Ian Tessier <itessier@google.com> wrote: > Oops, I did indeed leave out armv(4|5)t. Thanks for fixing it. > > Interestingly, with the non-UAL version of strcpy.c the mov instruction gets > emitted as "adds r3, r0, #0", while in UAL (both gcc/clang) it's emitted as > "movs r3, r0". > > On Fri, Jul 21, 2017 at 3:21 AM, Richard Earnshaw (lists) > <Richard.Earnshaw@arm.com> wrote: >> >> 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(-) >> >> > ^ permalink raw reply [flat|nested] 4+ messages in thread
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2017-07-19 21:02 [PATCH] arm: Update strcpy.c to use UAL syntax Ian Tessier via newlib
2017-07-20 14:19 ` Corinna Vinschen
2017-07-21 10:21 ` Richard Earnshaw (lists)
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2017-07-21 21:13 ` Ian Tessier via newlib
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