Displaying 3 results from an estimated 3 matches for "loopinvariant".
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isloopinvariant
2008 Mar 01
0
[LLVMdev] Google Summer of Code Idea
...ethod, which
allows the implementation to give details analysis of the functions.
For example, we could implement full knowledge of printf/scanf side
effects, which would be useful (PR1604).
2. We need some way to reason about errno. Consider a loop like this:
for ()
x += sqrt(loopinvariant);
We'd like to transform this into:
t = sqrt(loopinvariant);
for ()
x += t;
This transformation is safe, because the value of errno isn't
otherwise changed in the loop and the exit value of errno from the
loop is the same. We currently can't do this, bec...
2008 Mar 01
2
[LLVMdev] Google Summer of Code Idea
> Ok. I think the most important thing to keep in mind, if you want
> this to be useful for LLVM, is for it to be sound in the presence of
> incomplete programs. I think it would be very interesting to have a
> BDD based analysis in LLVM, it would be useful for performance
> comparisons and many other things, even if it isn't turned on by
> default. However, it must
2009 Nov 04
0
[LLVMdev] idempotence
The LLVM projects page says this:
"We need some way to reason about errno. Consider a loop like this:
for ()
x += sqrt(loopinvariant);"
and:
"The hard part of this project is figuring out how to describe errno in
the optimizer"
The important property here is the idempotence of sqrt(): it is
potentially side-effecting, but that side effect is independent of the
number of times it is called (with the same argu...