From a363a0bdefd2e798a83acd8998591b5b07c4256e Mon Sep 17 00:00:00 2001
From: Devang Patel <dpatel@apple.com>
Date: Sat, 11 Nov 2006 00:42:16 +0000
Subject: [PATCH] Keep track of analysis required by the passes. Force use of
 new pass manager if a pass does not preserve analysis that is used by other
 passes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31659 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/PassManager.h |  4 ++--
 lib/VMCore/PassManager.cpp | 23 ++++++++++++++++++-----
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/include/llvm/PassManager.h b/include/llvm/PassManager.h
index 23c30862106..075a572fb33 100644
--- a/include/llvm/PassManager.h
+++ b/include/llvm/PassManager.h
@@ -119,8 +119,8 @@ public:
   void removeDeadPasses() { /* TODO : Implement */ }
 
 private:
-   // Required set of analysis for the passes managed by this manager
-  std::vector<AnalysisID> RequiredSet;
+   // Analysis required by the passes managed by this manager
+  std::vector<AnalysisID> RequiredAnalysis;
 };
 
 /// PassManager_New manages ModulePassManagers
diff --git a/lib/VMCore/PassManager.cpp b/lib/VMCore/PassManager.cpp
index ad5a5dd79bc..27a86b65a68 100644
--- a/lib/VMCore/PassManager.cpp
+++ b/lib/VMCore/PassManager.cpp
@@ -142,9 +142,18 @@ bool CommonPassManagerImpl::manageablePass(Pass *P) {
   AnalysisUsage AnUsage;
   P->getAnalysisUsage(AnUsage);
 
-  // If this pass is not preserving information that is required by the other passes
-  // managed by this manager then use new manager
-  // TODO
+  // If this pass is not preserving information that is required by the other
+  // passes managed by this manager then use new manager
+  if (!AnUsage.getPreservesAll()) {
+    const std::vector<AnalysisID> &PreservedSet = AnUsage.getPreservedSet();
+    for (std::vector<AnalysisID>::iterator I = RequiredAnalysis.begin(),
+           E = RequiredAnalysis.end(); I != E; ++I) {
+      if (std::find(PreservedSet.begin(), PreservedSet.end(), *I) == 
+          PreservedSet.end())
+        // This analysis is not preserved. Need new manager.
+        return false;
+    }
+  }
   return true;
 }
 
@@ -157,8 +166,12 @@ bool CommonPassManagerImpl::analysisCurrentlyAvailable(AnalysisID AID) {
 
 /// Augment RequiredSet by adding analysis required by pass P.
 void CommonPassManagerImpl::noteDownRequiredAnalysis(Pass *P) {
+  AnalysisUsage AnUsage;
+  P->getAnalysisUsage(AnUsage);
+  const std::vector<AnalysisID> &RequiredSet = AnUsage.getRequiredSet();
 
-  // TODO
+  // FIXME: What about duplicates ?
+  RequiredAnalysis.insert(RequiredAnalysis.end(), RequiredSet.begin(), RequiredSet.end());
 }
 
 /// Remove AnalysisID from the RequiredSet
@@ -375,7 +388,7 @@ PassManagerImpl_New::add(Pass *P) {
 bool
 PassManagerImpl_New::addPass(Pass *P) {
 
-  if (!activeManager) {
+  if (!activeManager || !activeManager->addPass(P)) {
     activeManager = new ModulePassManager_New();
     PassManagers.push_back(activeManager);
   }
-- 
2.34.1