[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

2 files changed, 11 insertions, 0 deletions

diff --git a/llvm/lib/IR/Dominators.cpp b/llvm/lib/IR/Dominators.cpp
index 1880807da7e..009326825cd 100644
--- a/llvm/lib/IR/Dominators.cpp
+++ b/llvm/lib/IR/Dominators.cpp
@@ -73,6 +73,15 @@ template void llvm::Calculate<Function, Inverse<BasicBlock *>>(
         GraphTraits<Inverse<BasicBlock *>>::NodeRef>::type> &DT,
     Function &F);
 
+bool DominatorTree::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<DominatorTreeAnalysis>();
+  return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Function>>() ||
+           PAC.preservedSet<CFGAnalyses>());
+}
+
 // dominates - Return true if Def dominates a use in User. This performs
 // the special checks necessary if Def and User are in the same basic block.
 // Note that Def doesn't dominate a use in Def itself!
diff --git a/llvm/lib/IR/PassManager.cpp b/llvm/lib/IR/PassManager.cpp
index 8f68bb1daec..47fdfedfdde 100644
--- a/llvm/lib/IR/PassManager.cpp
+++ b/llvm/lib/IR/PassManager.cpp
@@ -91,4 +91,6 @@ bool FunctionAnalysisManagerModuleProxy::Result::invalidate(
 }
 }
 
+AnalysisSetKey CFGAnalyses::SetKey;
+
 AnalysisSetKey PreservedAnalyses::AllAnalysesKey;