On 17/11/15 05:55, David Wohlferd wrote: > How much pessimism are we talking here? Wouldn't clobbering everything > effectively force the reloading of (some? most? all?) registers? And > more memory will be needed to store things that used to just require > registers?
No, really not. It only affects locals whose address has been taken and is live at that point. > Along with a few more memory writes? A single line of basic asm, > even a comment, could have a non-trivial impact on the code that > gets generated. > > One common use I've seen for basic asm is "int $3" on x86 to break into > the debugger (the basic asm docs use this as a sample). Changing this to > a clobber-everything will make what used to be a minimally intrusive way > to debug code into a high impact operation that may obscure the very > thing being debugged. I think that's really pretty unlikely. Besides, if you need a breakpoint for debugging you really don't want operations to move across that breakpoint. Andrew.
