On 01/16/2017 10:32 AM, Xuefer wrote:
without -flto or without -O2 produce good (expected) result:
================================
configure:5332: checking for dlsym
...
It isn't the linker that is the problem here. It is the compiler. But
it isn't a compiler bug. An optimizing compiler is supposed to optimize
code like this.
I'd say the main problem is trying to use -flto at configure time. This
is likely to break lots of configure scripts.
char (*f) ();
However, this particular problem I can fix with gcc by changing this line to
char (* volatile f) ();
and now gcc won't optimize away the store, even with -flto.
Unfortunately, I can't check LLVM at the moment, as I don't have LLVM
-flto support set up on any of my machines at the moment.
So this can be fixed by not using -flto at configure time, or by
modifying configure scripts to use volatile. There is no linker or
compiler fix to make here.
Jim
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