support asm on armcc5

[liudongmiao]

Description

armcc5 use a different asm syntax, it uses c/c++ variable directly.

Status

READY

Requires Backporting

NO

Migrations

NO

Additional comments

I have used this on Brevent Booster (USB Dongle to simulate ADB) since 2018.
However, I don't know whether armcc5 should be supported.

Steps to test or reproduce

This is a rewrite for current gnu version of umlal.
However, some codes are rearranged.

MULADDC_INIT of gnu version

ldr    r0, %3   /* s */
ldr    r1, %4   /* d */
ldr    r2, %5   /* c */
ldr    r3, %6   /* b */

No need for armcc5.

MULADDC_CORE of gnu version

ldr    r4, [r0], #4             /* r0 = s, r4 = *s, then ++s */
mov    r5, #0
ldr    r6, [r1]                 /* r1 = d, r6 = *d */
umlal  r2, r5, r3, r4           /* r2 = c, r3 = b, r4 = *s => umlal c, r5, b, *s */
adds   r7, r6, r2               /* r6 = *d, r2 = c => adds r7, *d, c */
adc    r2, r5, #0               /* r2 = c => adc c, r5, #0 */
str    r7, [r1], #4             /* r1 = d, *d = r7, then ++d */

So, armcc5 is the same with gnu's syntax.
However, we defined a tmp r.

MULADDC_STOP of gnu version

str    r2, %0           /* store r2 (c) to c */
str    r1, %1           /* store r1 (d) to d */
str    r0, %2           /* store r0 (s) to s */

No need for armcc5.

[RonEld]

Hi @liudongmiao
Thank you for your contribution!
In addition, unfortunately our policy is to not accept contributions, without a Contributor’s Licence Agreement (CLA) signed or authorised by yourself or your employer.

If this is a personal contribution, the easiest way to do this is if you create an mbed account and accept this click through agreement. Alternatively, you can find a slightly different agreement to sign here, which can be signed and returned to us, and is applicable if you don't want to create an mbed account or alternatively if this is a corporate contribution.

Thanks for your understanding and again, thanks for the contribution!

[liudongmiao]

it seems some checks were not successful. and I cannot visit the details.

@RonEld could you help to check this?
https://jenkins-internal.mbed.com/job/mbedtls-pr-multibranch/job/PR-2533-head/1/display/redirect

If you want to accept this pull request, then I will register for CLA.

[RonEld]

@liudongmiao The failure is in the following test:

test_asan_remove_peer_certificate: test: ssl-opt.sh, !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE

As mentioned, In order for us to review and accept this PR, we would need to ask you to accept the CLA.

[liudongmiao]

@RonEld Thanks, just sent scanned cla in pdf via email.

[RonEld]

@liudongmiao Thank you for submitting the CLA!
As mentioned in Email, it has been sent for processing, and will probably be approved in the near future

[liudongmiao]

Finally, I move __ARMCC_VERSION to outside of __GNUC__, and merge umaal from #1618.

Currently, the asm for arm in __GNUC__ is three variants:

• non-thumb2
• umaal, defined by __ARM_FEATURE_DSP
• umlal, defined by __thumb2__

I have check the macro, then see the difference.

For armcc6, use command:

armclang --target=arm-arm-none-eabi -mcpu=cortex-m1 -E -dM - </dev/null
# for umlal
armclang --target=arm-arm-none-eabi -mcpu=cortex-m3 -E -dM - </dev/null
# for umaal
armclang --target=arm-arm-none-eabi -mcpu=cortex-m4 -E -dM - </dev/null

For armcc5, use command:

armcc --cpu=Cortex-M1 --list-macros - </dev/null
# for umlal
armcc --cpu=Cortex-M3 --list-macros - </dev/null
# for umaal
armcc --cpu=Cortex-M4 --list-macros - </dev/null

In the output, there is no __thumb2__ nor __ARM_FEATURE_DSP macros, but there are:

• m3, __TARGET_FEATURE_MULTIPLY(armcc5) vs __thumb2__ (armcc6, gnuc or armclang)
• m4, __TARGET_FEATURE_DSPMUL(armcc5) vs __ARM_FEATURE_DSP (armcc6, gnuc or armclang)

And the public documents show __TARGET_FEATURE_MULTIPLY is related with umlal (MULAL seems be a typo for UMLAL in reference), __TARGET_FEATURE_DSPMUL is related with DSP-enhanced multiplier.

• keil: http://www.keil.com/support/man/docs/armcc/armcc_chr1359125007083.htm
• armcc: https://developer.arm.com/docs/dui0472/latest/compiler-specific-features/predefined-macros

I have explained the umlal and use in product since 2018.
For umaal, I only checked the asm output with gnuc, don't use in product now.
(umaal was merged in 2018.10, at that time I have finished the product.
And the product is m4 using RSA 2048 encrypt, from #1618, there seems be little enhance 3%.)

[daverodgman]

Closing; armcc 5 is now out of support.