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a395eac8a8
r243382 changed the behavior to always require a set of memchecks to be passed to LoopVer. This change restores the prior behavior as an alternative to the new behavior. This allows the checks to be implicitly taken from the LAA object. Patch by Ashutosh Nema! git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@244763 91177308-0d34-0410-b5e6-96231b3b80d8
100 lines
3.7 KiB
C++
100 lines
3.7 KiB
C++
//===- LoopVersioning.h - Utility to version a loop -------------*- C++ -*-===//
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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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// This file defines a utility class to perform loop versioning. The versioned
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// loop speculates that otherwise may-aliasing memory accesses don't overlap and
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// emits checks to prove this.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TRANSFORMS_UTILS_LOOPVERSIONING_H
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#define LLVM_TRANSFORMS_UTILS_LOOPVERSIONING_H
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#include "llvm/Transforms/Utils/ValueMapper.h"
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namespace llvm {
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class Loop;
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class LoopAccessInfo;
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class LoopInfo;
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/// \brief This class emits a version of the loop where run-time checks ensure
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/// that may-alias pointers can't overlap.
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///
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/// It currently only supports single-exit loops and assumes that the loop
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/// already has a preheader.
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class LoopVersioning {
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public:
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/// \brief Expects MemCheck, LoopAccessInfo, Loop, LoopInfo, DominatorTree
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/// as input. It uses runtime check provided by user.
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LoopVersioning(SmallVector<RuntimePointerChecking::PointerCheck, 4> Checks,
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const LoopAccessInfo &LAI, Loop *L, LoopInfo *LI,
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DominatorTree *DT);
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/// \brief Expects LoopAccessInfo, Loop, LoopInfo, DominatorTree as input.
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/// It uses default runtime check provided by LoopAccessInfo.
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LoopVersioning(const LoopAccessInfo &LAInfo, Loop *L, LoopInfo *LI,
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DominatorTree *DT);
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/// \brief Performs the CFG manipulation part of versioning the loop including
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/// the DominatorTree and LoopInfo updates.
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///
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/// The loop that was used to construct the class will be the "versioned" loop
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/// i.e. the loop that will receive control if all the memchecks pass.
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///
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/// This allows the loop transform pass to operate on the same loop regardless
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/// of whether versioning was necessary or not:
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///
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/// for each loop L:
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/// analyze L
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/// if versioning is necessary version L
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/// transform L
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void versionLoop(Pass *P);
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/// \brief Adds the necessary PHI nodes for the versioned loops based on the
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/// loop-defined values used outside of the loop.
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///
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/// This needs to be called after versionLoop if there are defs in the loop
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/// that are used outside the loop. FIXME: this should be invoked internally
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/// by versionLoop and made private.
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void addPHINodes(const SmallVectorImpl<Instruction *> &DefsUsedOutside);
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/// \brief Returns the versioned loop. Control flows here if pointers in the
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/// loop don't alias (i.e. all memchecks passed). (This loop is actually the
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/// same as the original loop that we got constructed with.)
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Loop *getVersionedLoop() { return VersionedLoop; }
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/// \brief Returns the fall-back loop. Control flows here if pointers in the
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/// loop may alias (i.e. one of the memchecks failed).
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Loop *getNonVersionedLoop() { return NonVersionedLoop; }
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private:
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/// \brief The original loop. This becomes the "versioned" one. I.e.,
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/// control flows here if pointers in the loop don't alias.
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Loop *VersionedLoop;
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/// \brief The fall-back loop. I.e. control flows here if pointers in the
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/// loop may alias (memchecks failed).
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Loop *NonVersionedLoop;
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/// \brief This maps the instructions from VersionedLoop to their counterpart
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/// in NonVersionedLoop.
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ValueToValueMapTy VMap;
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/// \brief The set of checks that we are versioning for.
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SmallVector<RuntimePointerChecking::PointerCheck, 4> Checks;
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/// \brief Analyses used.
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const LoopAccessInfo &LAI;
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LoopInfo *LI;
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DominatorTree *DT;
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};
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}
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#endif
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