Optimize errno decoding. - #57
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The current code evaluates "*(int *)__error()" each time a syscall returns an error, matching the declaration of errno(). This is slow, as it involves executing code in the debugged process. Instead, we can evaluate and cache "(int *)__error()" once per thread, which gives us the per-thread location of errno, and simply dereference the pointer when we want the current errno.
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The current code evaluates "*(int *)__error()" each time a syscall returns an error, matching the declaration of errno(). This is slow, as it involves executing code in the debugged process.
Instead, we can evaluate and cache "(int *)__error()" once per thread, which gives us the per-thread location of errno, and simply dereference the pointer when we want the current errno.