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