Add a CFL Alias Analysis implementation

This provides an implementation of CFL alias analysis (including some
supporting data structures). Currently, we don't have any extremely fancy
features, sans some interprocedural analysis (i.e. no field sensitivity, etc.),
and we do best sitting behind BasicAA + TBAA. In such a configuration, we take
~0.6-0.8% of total compile time, and give ~7-8% NoAlias responses to queries
TBAA and BasicAA couldn't answer when bootstrapping LLVM. In testing this on
other projects, we've seen up to 10.5% of queries dropped by BasicAA+TBAA
answered with NoAlias by this algorithm.

Patch by George Burgess IV (with minor modifications by me -- mostly adapting
some BasicAA tests), thanks!

llvm-svn: 216970

1 files changed, 1 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/Analysis.cpp b/llvm/lib/Analysis/Analysis.cpp
index 010ad7440e6..f64bf0ec2c4 100644
--- a/llvm/lib/Analysis/Analysis.cpp
+++ b/llvm/lib/Analysis/Analysis.cpp
@@ -34,6 +34,7 @@ void llvm::initializeAnalysis(PassRegistry &Registry) {
   initializeCFGPrinterPass(Registry);
   initializeCFGOnlyViewerPass(Registry);
   initializeCFGOnlyPrinterPass(Registry);
+  initializeCFLAliasAnalysisPass(Registry);
   initializeDependenceAnalysisPass(Registry);
   initializeDelinearizationPass(Registry);
   initializeDominanceFrontierPass(Registry);