Coverage Report

Created: 2019-07-24 05:18

/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/include/llvm/Transforms/Scalar/LICM.h
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//===- LICM.h - Loop Invariant Code Motion Pass -------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass performs loop invariant code motion, attempting to remove as much
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// code from the body of a loop as possible.  It does this by either hoisting
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// code into the preheader block, or by sinking code to the exit blocks if it is
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// safe.  This pass also promotes must-aliased memory locations in the loop to
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// live in registers, thus hoisting and sinking "invariant" loads and stores.
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//
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// This pass uses alias analysis for two purposes:
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//
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//  1. Moving loop invariant loads and calls out of loops.  If we can determine
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//     that a load or call inside of a loop never aliases anything stored to,
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//     we can hoist it or sink it like any other instruction.
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//  2. Scalar Promotion of Memory - If there is a store instruction inside of
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//     the loop, we try to move the store to happen AFTER the loop instead of
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//     inside of the loop.  This can only happen if a few conditions are true:
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//       A. The pointer stored through is loop invariant
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//       B. There are no stores or loads in the loop which _may_ alias the
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//          pointer.  There are no calls in the loop which mod/ref the pointer.
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//     If these conditions are true, we can promote the loads and stores in the
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//     loop of the pointer to use a temporary alloca'd variable.  We then use
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//     the SSAUpdater to construct the appropriate SSA form for the value.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TRANSFORMS_SCALAR_LICM_H
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#define LLVM_TRANSFORMS_SCALAR_LICM_H
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#include "llvm/Analysis/LoopInfo.h"
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#include "llvm/IR/PassManager.h"
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#include "llvm/Transforms/Scalar/LoopPassManager.h"
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namespace llvm {
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extern cl::opt<unsigned> SetLicmMssaOptCap;
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extern cl::opt<unsigned> SetLicmMssaNoAccForPromotionCap;
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/// Performs Loop Invariant Code Motion Pass.
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class LICMPass : public PassInfoMixin<LICMPass> {
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  unsigned LicmMssaOptCap;
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  unsigned LicmMssaNoAccForPromotionCap;
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public:
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  LICMPass()
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      : LicmMssaOptCap(SetLicmMssaOptCap),
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        LicmMssaNoAccForPromotionCap(SetLicmMssaNoAccForPromotionCap) {}
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  LICMPass(unsigned LicmMssaOptCap, unsigned LicmMssaNoAccForPromotionCap)
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      : LicmMssaOptCap(LicmMssaOptCap),
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        LicmMssaNoAccForPromotionCap(LicmMssaNoAccForPromotionCap) {}
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  PreservedAnalyses run(Loop &L, LoopAnalysisManager &AM,
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                        LoopStandardAnalysisResults &AR, LPMUpdater &U);
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};
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} // end namespace llvm
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#endif // LLVM_TRANSFORMS_SCALAR_LICM_H