From 2296182181521c0b1803a0cd10b098fcfdab1c92 Mon Sep 17 00:00:00 2001
From: serge-sans-paille <sguelton@redhat.com>
Date: Fri, 28 Aug 2020 10:24:48 +0200
Subject: [PATCH] Skip analysis re-computation when no changes are reported

This is a follow-up to https://reviews.llvm.org/D80707, generalized to
CallGraphSCC, Loop and Region

Differential Revision: https://reviews.llvm.org/D86442
---
 llvm/lib/Analysis/CallGraphSCCPass.cpp | 3 ++-
 llvm/lib/Analysis/LoopPass.cpp         | 3 ++-
 llvm/lib/Analysis/RegionPass.cpp       | 3 ++-
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Analysis/CallGraphSCCPass.cpp b/llvm/lib/Analysis/CallGraphSCCPass.cpp
index 17dd4dd..2de18fe 100644
--- a/llvm/lib/Analysis/CallGraphSCCPass.cpp
+++ b/llvm/lib/Analysis/CallGraphSCCPass.cpp
@@ -489,7 +489,8 @@ bool CGPassManager::RunAllPassesOnSCC(CallGraphSCC &CurSCC, CallGraph &CG,
     dumpPreservedSet(P);
 
     verifyPreservedAnalysis(P);
-    removeNotPreservedAnalysis(P);
+    if (LocalChanged)
+      removeNotPreservedAnalysis(P);
     recordAvailableAnalysis(P);
     removeDeadPasses(P, "", ON_CG_MSG);
   }
diff --git a/llvm/lib/Analysis/LoopPass.cpp b/llvm/lib/Analysis/LoopPass.cpp
index 317b957..50ed1cf 100644
--- a/llvm/lib/Analysis/LoopPass.cpp
+++ b/llvm/lib/Analysis/LoopPass.cpp
@@ -254,7 +254,8 @@ bool LPPassManager::runOnFunction(Function &F) {
         F.getContext().yield();
       }
 
-      removeNotPreservedAnalysis(P);
+      if (LocalChanged)
+        removeNotPreservedAnalysis(P);
       recordAvailableAnalysis(P);
       removeDeadPasses(P,
                        CurrentLoopDeleted ? "<deleted>"
diff --git a/llvm/lib/Analysis/RegionPass.cpp b/llvm/lib/Analysis/RegionPass.cpp
index 1e1971f..ace6824 100644
--- a/llvm/lib/Analysis/RegionPass.cpp
+++ b/llvm/lib/Analysis/RegionPass.cpp
@@ -135,7 +135,8 @@ bool RGPassManager::runOnFunction(Function &F) {
         verifyPreservedAnalysis(P);
       }
 
-      removeNotPreservedAnalysis(P);
+      if (LocalChanged)
+        removeNotPreservedAnalysis(P);
       recordAvailableAnalysis(P);
       removeDeadPasses(P,
                        (!isPassDebuggingExecutionsOrMore() || skipThisRegion) ?
-- 
2.7.4