Hi, I noticed PR71716 and I want to enable ATOMIC_COMPARE_EXCHANGE internal-fn optimization for floating type or types contains padding (e.g., long double). Please tell me if I happen to make any mistakes, Thanks!
Firstly, about the concerns of sNaNs float/double value, it seems work well and shall have been covered by testsuite/gcc.dg/atomic/c11-atomic-exec-5.c Secondly, since ATOMIC_COMPARE_EXCHANGE is only enabled when expected var is only addressable because of the call, the padding bits can not be modified by any other stmts. So we can save all bits after ATOMIC_COMPARE_EXCHANGE call and extract the padding bits. After first iteration, the extracted padding bits can be mixed with the expected var. Bootstrapped/regtested on x86_64-linux.
