Date: Sat, 28 Jul 2012 20:31:39 -0400 From: Rich Felker <dalias@...ifal.cx> To: musl@...ts.openwall.com Subject: ARM floating point setjmp/longjmp support Hi, The attached patch is intended to add runtime-conditional support for saving FPA/VFP/iWMMXt call-preserved registers across setjmp/longjmp. It's modelled based on what the code in uClibc does, so I'm not sure if it's correct, but it seems to be, and it avoids using mnemonics that could fail depending on -march/-mfpu settings. Could someone familiar with ARM take a look at it and see if it makes sense, or even better, if it works? I'm a little bit doubtful about whether the iWMMXt stuff is needed (i.e. whether it's part of any ABI one could reasonably expect to be honored) or worth the cost, and I'm unsure if there are other optional coprocessor registers we should be checking for and possibly saving. Also, there's the question of whether the conditional-execution coprocessor instructions will generate illegal instruction exceptions on machines without the coprocessor when the condition check fails. One site (http://www.peter-cockerell.net/aalp/html/app-a.html) claims they're safe, but I'd like to see something more authoritative. Rich View attachment "arm-fp-sjlj.diff" of type "text/plain" (1420 bytes)
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