[PATCH] D92309: [LegacyPM] Update InversedLastUser on the fly. NFC.

[Jay Foad via Phabricator via llvm-commits]

foad created this revision.
Herald added subscribers: llvm-commits, dexonsmith, hiraditya.
Herald added a project: LLVM.
foad requested review of this revision.

This speeds up setLastUser enough to give a 5% to 10% speed up on
trivial invocations of opt and llc, as measured by:

perf stat -r 100 opt -S -o /dev/null -O3 /dev/null
perf stat -r 100 llc -march=amdgcn /dev/null -filetype null


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D92309

Files:
  llvm/include/llvm/IR/LegacyPassManagers.h
  llvm/lib/IR/LegacyPassManager.cpp


Index: llvm/lib/IR/LegacyPassManager.cpp
===================================================================
--- llvm/lib/IR/LegacyPassManager.cpp
+++ llvm/lib/IR/LegacyPassManager.cpp
@@ -641,7 +641,12 @@
     PDepth = P->getResolver()->getPMDataManager().getDepth();
 
   for (Pass *AP : AnalysisPasses) {
-    LastUser[AP] = P;
+    // Record P as the new last user of AP.
+    auto &LastUserOfAP = LastUser[AP];
+    if (LastUserOfAP)
+      InversedLastUser[LastUserOfAP].erase(AP);
+    LastUserOfAP = P;
+    InversedLastUser[P].insert(AP);
 
     if (P == AP)
       continue;
@@ -671,13 +676,13 @@
     if (P->getResolver())
       setLastUser(LastPMUses, P->getResolver()->getPMDataManager().getAsPass());
 
-
     // If AP is the last user of other passes then make P last user of
     // such passes.
-    for (auto &LU : LastUser) {
-      if (LU.second == AP)
-        LU.second = P;
-    }
+    auto &LastUsedByAP = InversedLastUser[AP];
+    for (Pass *L : LastUsedByAP)
+      LastUser[L] = P;
+    InversedLastUser[P].insert(LastUsedByAP.begin(), LastUsedByAP.end());
+    LastUsedByAP.clear();
   }
 }
 
@@ -923,11 +928,6 @@
   // Initailize other pass managers
   for (PMDataManager *IPM : IndirectPassManagers)
     IPM->initializeAnalysisInfo();
-
-  for (auto LU : LastUser) {
-    SmallPtrSet<Pass *, 8> &L = InversedLastUser[LU.second];
-    L.insert(LU.first);
-  }
 }
 
 /// Destructor
Index: llvm/include/llvm/IR/LegacyPassManagers.h
===================================================================
--- llvm/include/llvm/IR/LegacyPassManagers.h
+++ llvm/include/llvm/IR/LegacyPassManagers.h
@@ -233,8 +233,6 @@
   DenseMap<Pass *, Pass *> LastUser;
 
   // Map to keep track of passes that are last used by a pass.
-  // This inverse map is initialized at PM->run() based on
-  // LastUser map.
   DenseMap<Pass *, SmallPtrSet<Pass *, 8> > InversedLastUser;
 
   /// Immutable passes are managed by top level manager.


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