This commit splits DominanceAnalysis into two analysis (Dom and PDom) that
can be cached and invalidates using the common FunctionAnalysisBase interface
independent of one another.
Swift SVN r26643
The old invalidation lattice was incorrect because changes to control flow could cause changes to the
call graph, so we've decided to change the way passes invalidate analysis. In the new scheme, the lattice
is replaced with a list of traits that passes preserve or invalidate. The current traits are Calls and Branches.
Now, passes report which traits they preserve, which is the opposite of the previous implementation where
passes needed to report what they invalidate.
Node: I tried to limit the changes in this commit to mechanical changes to ease the review. I will cleanup some
of the code in a following commit.
Swift SVN r26449
Use it in loop rotation.
The pattern to update analysis information is:
// The AnalysisInfo was preserved for this function.
if (Changed) {
// Preserve the analyis for this function by decoupling it from the analysis
// cache.
auto PreservedAnalysis = Analysis.preserveAnalysis(Function);
// Invalidate analysis for this function.
PM.invalidateAnalysis(Function, InvalidationKind::CFG);
// Update the preserved analysis for this function.
Analysis.updateAnalysis(F, std::move(PreservedAnalysis));
}
Swift SVN r19918
