Changes in directory llvm/lib/VMCore:
PassManager.cpp updated: 1.34 -> 1.35
---
Log message:
Add overview of pass manager.
---
Diffs of the changes: (+64 -0)
PassManager.cpp | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 64 insertions(+)
Index: llvm/lib/VMCore/PassManager.cpp
diff -u llvm/lib/VMCore/PassManager.cpp:1.34
llvm/lib/VMCore/PassManager.cpp:1.35
--- llvm/lib/VMCore/PassManager.cpp:1.34 Wed Dec 6 19:30:31 2006
+++ llvm/lib/VMCore/PassManager.cpp Thu Dec 7 12:23:30 2006
@@ -20,6 +20,70 @@
#include <map>
using namespace llvm;
+//===----------------------------------------------------------------------===//
+// Overview:
+// The Pass Manager Infrastructure manages passes. It's responsibilities are:
+//
+// o Manage optimization pass execution order
+// o Make required Analysis information available before pass P is run
+// o Release memory occupied by dead passes
+// o If Analysis information is dirtied by a pass then regenerate Analysis
+// information before it is consumed by another pass.
+//
+// Pass Manager Infrastructure uses multipe pass managers. They are
PassManager,
+// FunctionPassManager, ModulePassManager, BasicBlockPassManager. This class
+// hierarcy uses multiple inheritance but pass managers do not derive from
+// another pass manager.
+//
+// PassManager and FunctionPassManager are two top level pass manager that
+// represents the external interface of this entire pass manager infrastucture.
+//
+// Important classes :
+//
+// [o] class PMTopLevelManager;
+//
+// Two top level managers, PassManager and FunctionPassManager, derive from
+// PMTopLevelManager. PMTopLevelManager manages information used by top level
+// managers such as last user info.
+//
+// [o] class PMDataManager;
+//
+// PMDataManager manages information, e.g. list of available analysis info,
+// used by a pass manager to manage execution order of passes. It also provides
+// a place to implement common pass manager APIs. All pass managers derive from
+// PMDataManager.
+//
+// [o] class BasicBlockPassManager : public FunctionPass, public PMDataManager;
+//
+// BasicBlockPassManager manages BasicBlockPasses.
+//
+// [o] class FunctionPassManager;
+//
+// This is a external interface used by JIT to manage FunctionPasses. This
+// interface relies on FunctionPassManagerImpl to do all the tasks.
+//
+// [o] class FunctionPassManagerImpl : public ModulePass, PMDataManager,
+// public PMTopLevelManager;
+//
+// FunctionPassManagerImpl is a top level manager. It manages FunctionPasses
+// and BasicBlockPassManagers.
+//
+// [o] class ModulePassManager : public Pass, public PMDataManager;
+//
+// ModulePassManager manages ModulePasses and FunctionPassManagerImpls.
+//
+// [o] class PassManager;
+//
+// This is a external interface used by various tools to manages passes. It
+// relies on PassManagerImpl to do all the tasks.
+//
+// [o] class PassManagerImpl : public Pass, public PMDataManager,
+// public PMDTopLevelManager
+//
+// PassManagerImpl is a top level pass manager responsible for managing
+// ModulePassManagers.
+//===----------------------------------------------------------------------===//
+
namespace llvm {
/// CommonPassManagerImpl helps pass manager analysis required by
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