Commit missing PollyModule.cpp file

llvm-svn: 202764

polly/lib/PollyModule.cpp

@@ -0,0 +1,71 @@
+//===------ ModuleInitializers.cpp - Initialize the Polly Module          --===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//===----------------------------------------------------------------------===//
+
+#include "polly/RegisterPasses.h"
+#include "llvm/Transforms/IPO/PassManagerBuilder.h"
+
+namespace {
+
+/// @brief Initialize Polly passes when library is loaded.
+///
+/// We use the constructor of a statically declared object to initialize the
+/// different Polly passes right after the Polly library is loaded. This ensures
+/// that the Polly passes are available e.g. in the 'opt' tool.
+class StaticInitializer {
+public:
+  StaticInitializer() {
+    llvm::PassRegistry &Registry = *llvm::PassRegistry::getPassRegistry();
+    polly::initializePollyPasses(Registry);
+  }
+};
+static StaticInitializer InitializeEverything;
+
+static void
+registerPollyEarlyAsPossiblePasses(const llvm::PassManagerBuilder &Builder,
+                                   llvm::PassManagerBase &PM) {
+
+  if (!polly::shouldEnablePolly())
+    return;
+
+  polly::registerPollyPasses(PM);
+}
+
+/// @brief Register Polly to be available as an optimizer
+///
+/// We currently register Polly such that it runs as early as possible. This has
+/// several implications:
+///
+///   1) We need to schedule more canonicalization passes
+///
+///   As nothing is run before Polly, it is necessary to run a set of preparing
+///   transformations before Polly to canonicalize the LLVM-IR and to allow
+///   Polly to detect and understand the code.
+///
+///   2) LICM and LoopIdiom pass have not yet been run
+///
+///   Loop invariant code motion as well as the loop idiom recognition pass make
+///   it more difficult for Polly to transform code. LICM may introduce
+///   additional data dependences that are hard to eliminate and the loop idiom
+///   recognition pass may introduce calls to memset that we currently do not
+///   understand. By running Polly early enough (meaning before these passes) we
+///   avoid difficulties that may be introduced by these passes.
+///
+///   3) We get the full -O3 optimization sequence after Polly
+///
+///   The LLVM-IR that is generated by Polly has been optimized on a high level,
+///   but it may be rather inefficient on the lower/scalar level. By scheduling
+///   Polly before all other passes, we have the full sequence of -O3
+///   optimizations behind us, such that inefficiencies on the low level can
+///   be optimized away.
+static llvm::RegisterStandardPasses
+RegisterPollyOptimizer(llvm::PassManagerBuilder::EP_EarlyAsPossible,
+                       registerPollyEarlyAsPossiblePasses);
+} // end of anonymous namespace.