Re: Obscure crashes due to gcc 4.9 -O2 = -fisolate-erroneous-paths-dereference

2015-02-19 Thread Jeff Prothero
(Thanks to everyone for the helpful feedback!) Daniel Gutson wrote: what about then two warnings (disabled by default), one intended to tell the user each time the compiler removes a conditional (-fdelete-null-pointer-checks) and another intended to tell the user each time the compiler

Obscure crashes due to gcc 4.9 -O2 = -fisolate-erroneous-paths-dereference

2015-02-18 Thread Jeff Prothero
Starting with gcc 4.9, -O2 implicitly invokes -fisolate-erroneous-paths-dereference: which https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html documents as Detect paths that trigger erroneous or undefined behavior due to dereferencing a null pointer. Isolate those paths

Does -flto give gcc access to data addresses?

2014-09-11 Thread Jeff Prothero
Hi, I'm having trouble based on available docs like https://gcc.gnu.org/onlinedocs/gccint/LTO.html in understanding just what the gcc LTO framework is intended to be architecturally capable of. As a concrete motivating example, I have a 32K embedded program about 5% of which consists of