Messages in this thread | | | From | Segher Boessenkool <> | Subject | Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures | Date | Wed, 15 Aug 2007 20:31:25 +0200 |
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>> How does the compiler know that msleep() has got barrier()s? > > Because msleep_interruptible() is in a separate compilation unit, > the compiler has to assume that it might modify any arbitrary global.
No; compilation units have nothing to do with it, GCC can optimise across compilation unit boundaries just fine, if you tell it to compile more than one compilation unit at once.
What you probably mean is that the compiler has to assume any code it cannot currently see can do anything (insofar as allowed by the relevant standards etc.)
> In many cases, the compiler also has to assume that > msleep_interruptible() > might call back into a function in the current compilation unit, thus > possibly modifying global static variables.
It most often is smart enough to see what compilation-unit-local variables might be modified that way, though :-)
Segher
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