commit deb9ea3a8c842f279cf9d7db695760acd55be660
author Johannes Doerfert <jdoerfert@anl.gov> Fri Aug 23 15:42:19 2019 +0000
committer Johannes Doerfert <jdoerfert@anl.gov> Fri Aug 23 15:42:19 2019 +0000
tree 18d90e8996686ab27f4f31b93171b0895f7d6f6f
parent 91824678868d920a2fe7dc10fcac0a21966e6fc3

[Attributor][NFCI] Avoid lookups when resolving returned values

If the number of potentially returned values not change since the last
traversal we do not need to visit the returned values again. This works
as we only add values to the returned values set now.

Differential Revision: https://reviews.llvm.org/D66484

llvm-svn: 369770

llvm/lib/Transforms/IPO/Attributor.cpp

diff --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp
index 373e491..ea897d7 100644
--- a/llvm/lib/Transforms/IPO/Attributor.cpp
+++ b/llvm/lib/Transforms/IPO/Attributor.cpp
@@ -682,13 +682,18 @@
   /// return instructions that might return them.
   DenseMap<Value *, SmallSetVector<ReturnInst *, 4>> ReturnedValues;
 
+  /// Mapping to remember the number of returned values for a call site such
+  /// that we can avoid updates if nothing changed.
+  DenseMap<const CallBase *, unsigned> NumReturnedValuesPerKnownAA;
+
+  /// Set of unresolved calls returned by the associated function.
   SmallSetVector<CallBase *, 4> UnresolvedCalls;
 
   /// State flags
   ///
   ///{
-  bool IsFixed;
-  bool IsValidState;
+  bool IsFixed = false;
+  bool IsValidState = true;
   ///}
 
 public:
@@ -774,7 +779,6 @@
   /// See AbstractState::indicateOptimisticFixpoint(...).
   ChangeStatus indicateOptimisticFixpoint() override {
     IsFixed = true;
-    IsValidState &= true;
     return ChangeStatus::UNCHANGED;
   }
 
@@ -974,6 +978,15 @@
     if (Unresolved)
       continue;
 
+    // Now track transitively returned values.
+    unsigned &NumRetAA = NumReturnedValuesPerKnownAA[CB];
+    if (NumRetAA == RetValAA.getNumReturnValues()) {
+      LLVM_DEBUG(dbgs() << "[AAReturnedValues] Skip call as it has not "
+                           "changed since it was seen last\n");
+      continue;
+    }
+    NumRetAA = RetValAA.getNumReturnValues();
+
     for (auto &RetValAAIt : RetValAA.returned_values()) {
       Value *RetVal = RetValAAIt.first;
       if (Argument *Arg = dyn_cast<Argument>(RetVal)) {