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//===---------- Polly.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.
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