[PM] Introduce an analysis set used to preserve all analyses over

a function's CFG when that CFG is unchanged.

This allows transformation passes to simply claim they preserve the CFG
and analysis passes to check for the CFG being preserved to remove the
fanout of all analyses being listed in all passes.

I've gone through and removed or cleaned up as many of the comments
reminding us to do this as I could.

Differential Revision: https://reviews.llvm.org/D28627

llvm-svn: 292054

1 files changed, 9 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/LoopInfo.cpp b/llvm/lib/Analysis/LoopInfo.cpp
index 1b5d6e5d1b7..fb05e60e57d 100644
--- a/llvm/lib/Analysis/LoopInfo.cpp
+++ b/llvm/lib/Analysis/LoopInfo.cpp
@@ -610,6 +610,15 @@ LoopInfo::LoopInfo(const DominatorTreeBase<BasicBlock> &DomTree) {
   analyze(DomTree);
 }
 
+bool LoopInfo::invalidate(Function &F, const PreservedAnalyses &PA,
+                          FunctionAnalysisManager::Invalidator &) {
+  // Check whether the analysis, all analyses on functions, or the function's
+  // CFG have been preserved.
+  auto PAC = PA.getChecker<LoopAnalysis>();
+  return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>() ||
+           PAC.preservedSet<CFGAnalyses>());
+}
+
 void LoopInfo::markAsRemoved(Loop *Unloop) {
   assert(!Unloop->isInvalid() && "Loop has already been removed");
   Unloop->invalidate();