[PATCH, ARM 7/6] Enable atomics for ARMv8-M Mainline

["Thomas Preud'homme" <thomas.preudhomme@foss.arm.com>]

Hi,

This patch is part of a patch series to add support for ARMv8-M[1] to GCC. This specific patch enable atomics for ARMv8-M Mainline. No change is needed to existing patterns since Thumb-2 backend can already handle them fine.

[1] For a quick overview of ARMv8-M please refer to the initial cover letter.


ChangeLog entries are as follow:

*** gcc/ChangeLog ***

2015-12-17  Thomas Preud'homme  <thomas.preudhomme@arm.com>

        * config/arm/arm.h (TARGET_HAVE_LDACQ): Enable for ARMv8-M Mainline.


diff --git a/gcc/config/arm/arm.h b/gcc/config/arm/arm.h
index 1f79c37b5c36a410a2d500ba92c62a5ba4ca1178..fa2a6fb03ffd2ca53bfb7e7c8f03022b626880e0 100644
--- a/gcc/config/arm/arm.h
+++ b/gcc/config/arm/arm.h
@@ -258,7 +258,7 @@ extern void (*arm_lang_output_object_attributes_hook)(void);
 			     || arm_arch7) && arm_arch_notm)
 
 /* Nonzero if this chip supports load-acquire and store-release.  */
-#define TARGET_HAVE_LDACQ	(TARGET_ARM_ARCH >= 8 && arm_arch_notm)
+#define TARGET_HAVE_LDACQ	(TARGET_ARM_ARCH >= 8 && TARGET_32BIT)
 
 /* Nonzero if this chip provides the movw and movt instructions.  */
 #define TARGET_HAVE_MOVT	(arm_arch_thumb2 || arm_arch8)


Testing:

* Toolchain was built successfully with and without the ARMv8-M support patches with the following multilib list: armv6-m,armv7-m,armv7e-m,cortex-m7. The code generation for crtbegin.o, crtend.o, crti.o, crtn.o, libgcc.a, libgcov.a, libc.a, libg.a, libgloss-linux.a, libm.a, libnosys.a, librdimon.a, librdpmon.a, libstdc++.a and libsupc++.a is unchanged for all these targets. 

* GCC also showed no testsuite regression when targeting ARMv8-M Baseline compared to ARMv6-M on ARM Fast Models and when targeting ARMv6-M and ARMv7-M (compared to without the patch)
* GCC was bootstrapped successfully targeting Thumb-1 and targeting Thumb-2

Is this ok for stage3?

Best regards,

Thomas