[PM] Introduce the facilities for registering cross-IR-unit dependencies

that require deferred invalidation.

This handles the other real-world invalidation scenario that we have
cases of: a function analysis which caches references to a module
analysis. We currently do this in the AA aggregation layer and might
well do this in other places as well.

Since this is relative rare, the technique is somewhat more cumbersome.
Analyses need to register themselves when accessing the outer analysis
manager's proxy. This proxy is already necessarily present to allow
access to the outer IR unit's analyses. By registering here we can track
and trigger invalidation when that outer analysis goes away.

To make this work we need to enhance the PreservedAnalyses
infrastructure to support a (slightly) more explicit model for "sets" of
analyses, and allow abandoning a single specific analyses even when
a set covering that analysis is preserved. That allows us to describe
the scenario of preserving all Function analyses *except* for the one
where deferred invalidation has triggered.

We also need to teach the invalidator API to support direct ID calls
instead of always going through a template to dispatch so that we can
just record the ID mapping.

I've introduced testing of all of this both for simple module<->function
cases as well as for more complex cases involving a CGSCC layer.

Much like the previous patch I've not tried to fully update the loop
pass management layer because that layer is due to be heavily reworked
to use similar techniques to the CGSCC to handle updates. As that
happens, we'll have a better testing basis for adding support like this.

Many thanks to both Justin and Sean for the extensive reviews on this to
help bring the API design and documentation into a better state.

Differential Revision: https://reviews.llvm.org/D27198

llvm-svn: 290594

1 files changed, 45 insertions, 5 deletions

diff --git a/llvm/lib/IR/PassManager.cpp b/llvm/lib/IR/PassManager.cpp
index 7c478ea1cf6..8f68bb1daec 100644
--- a/llvm/lib/IR/PassManager.cpp
+++ b/llvm/lib/IR/PassManager.cpp
@@ -29,6 +29,10 @@ template <>
 bool FunctionAnalysisManagerModuleProxy::Result::invalidate(
     Module &M, const PreservedAnalyses &PA,
     ModuleAnalysisManager::Invalidator &Inv) {
+  // If literally everything is preserved, we're done.
+  if (PA.areAllPreserved())
+    return false; // This is still a valid proxy.
+
   // If this proxy isn't marked as preserved, then even if the result remains
   // valid, the key itself may no longer be valid, so we clear everything.
   //
@@ -37,18 +41,54 @@ bool FunctionAnalysisManagerModuleProxy::Result::invalidate(
   // Specifically, any FAM-cached results for those functions need to have been
   // forcibly cleared. When preserved, this proxy will only invalidate results
   // cached on functions *still in the module* at the end of the module pass.
-  if (!PA.preserved(FunctionAnalysisManagerModuleProxy::ID())) {
+  auto PAC = PA.getChecker<FunctionAnalysisManagerModuleProxy>();
+  if (!PAC.preserved() && !PAC.preservedSet<AllAnalysesOn<Module>>()) {
     InnerAM->clear();
     return true;
   }
 
-  // Otherwise propagate the invalidation event to all the remaining IR units.
-  for (Function &F : M)
-    InnerAM->invalidate(F, PA);
+  // Directly check if the relevant set is preserved.
+  bool AreFunctionAnalysesPreserved =
+      PA.allAnalysesInSetPreserved<AllAnalysesOn<Function>>();
+
+  // Now walk all the functions to see if any inner analysis invalidation is
+  // necessary.
+  for (Function &F : M) {
+    Optional<PreservedAnalyses> FunctionPA;
+
+    // Check to see whether the preserved set needs to be pruned based on
+    // module-level analysis invalidation that triggers deferred invalidation
+    // registered with the outer analysis manager proxy for this function.
+    if (auto *OuterProxy =
+            InnerAM->getCachedResult<ModuleAnalysisManagerFunctionProxy>(F))
+      for (const auto &OuterInvalidationPair :
+           OuterProxy->getOuterInvalidations()) {
+        AnalysisKey *OuterAnalysisID = OuterInvalidationPair.first;
+        const auto &InnerAnalysisIDs = OuterInvalidationPair.second;
+        if (Inv.invalidate(OuterAnalysisID, M, PA)) {
+          if (!FunctionPA)
+            FunctionPA = PA;
+          for (AnalysisKey *InnerAnalysisID : InnerAnalysisIDs)
+            FunctionPA->abandon(InnerAnalysisID);
+        }
+      }
+
+    // Check if we needed a custom PA set, and if so we'll need to run the
+    // inner invalidation.
+    if (FunctionPA) {
+      InnerAM->invalidate(F, *FunctionPA);
+      continue;
+    }
+
+    // Otherwise we only need to do invalidation if the original PA set didn't
+    // preserve all function analyses.
+    if (!AreFunctionAnalysesPreserved)
+      InnerAM->invalidate(F, PA);
+  }
 
   // Return false to indicate that this result is still a valid proxy.
   return false;
 }
 }
 
-AnalysisKey PreservedAnalyses::AllAnalysesKey;
+AnalysisSetKey PreservedAnalyses::AllAnalysesKey;