The ldrexd and strexd instructions are undefined for the ARMv7M
architecture, so we cannot use them to implement the
__sync_fetch_and_*_8 builtins. There is no other way to implement
these without OS support, so this patch #ifdef's these functions out
for M-class architectures.
There are no tests as I cannot find any existing tests for these
builtins.
I used the __ARM_ARCH_PROFILE predefine because __ARM_FEATURE_LDREX is
deprecated and not set by clang.
llvm-svn: 218601
Since these are primarily useful for deeply embedded targets where code size is
very important, they are each in a separate file making use of infrastructure
in sync-ops.h. This allows a linker to include just the functions that are
actually used.
rdar://problem/14736665
llvm-svn: 202812
Oliver Stannard