llvm-6502/include/llvm/Transforms/Utils/LoopUtils.h
Chandler Carruth 5a9cd4d44e [PM] Split the AssumptionTracker immutable pass into two separate APIs:
a cache of assumptions for a single function, and an immutable pass that
manages those caches.

The motivation for this change is two fold. Immutable analyses are
really hacks around the current pass manager design and don't exist in
the new design. This is usually OK, but it requires that the core logic
of an immutable pass be reasonably partitioned off from the pass logic.
This change does precisely that. As a consequence it also paves the way
for the *many* utility functions that deal in the assumptions to live in
both pass manager worlds by creating an separate non-pass object with
its own independent API that they all rely on. Now, the only bits of the
system that deal with the actual pass mechanics are those that actually
need to deal with the pass mechanics.

Once this separation is made, several simplifications become pretty
obvious in the assumption cache itself. Rather than using a set and
callback value handles, it can just be a vector of weak value handles.
The callers can easily skip the handles that are null, and eventually we
can wrap all of this up behind a filter iterator.

For now, this adds boiler plate to the various passes, but this kind of
boiler plate will end up making it possible to port these passes to the
new pass manager, and so it will end up factored away pretty reasonably.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225131 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-04 12:03:27 +00:00

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2.3 KiB
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//===- llvm/Transforms/Utils/LoopUtils.h - Loop utilities -*- C++ -*-=========//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines some loop transformation utilities.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TRANSFORMS_UTILS_LOOPUTILS_H
#define LLVM_TRANSFORMS_UTILS_LOOPUTILS_H
namespace llvm {
class AliasAnalysis;
class AssumptionCache;
class BasicBlock;
class DataLayout;
class DominatorTree;
class Loop;
class LoopInfo;
class Pass;
class ScalarEvolution;
BasicBlock *InsertPreheaderForLoop(Loop *L, Pass *P);
/// \brief Simplify each loop in a loop nest recursively.
///
/// This takes a potentially un-simplified loop L (and its children) and turns
/// it into a simplified loop nest with preheaders and single backedges. It
/// will optionally update \c AliasAnalysis and \c ScalarEvolution analyses if
/// passed into it.
bool simplifyLoop(Loop *L, DominatorTree *DT, LoopInfo *LI, Pass *PP,
AliasAnalysis *AA = nullptr, ScalarEvolution *SE = nullptr,
const DataLayout *DL = nullptr,
AssumptionCache *AC = nullptr);
/// \brief Put loop into LCSSA form.
///
/// Looks at all instructions in the loop which have uses outside of the
/// current loop. For each, an LCSSA PHI node is inserted and the uses outside
/// the loop are rewritten to use this node.
///
/// LoopInfo and DominatorTree are required and preserved.
///
/// If ScalarEvolution is passed in, it will be preserved.
///
/// Returns true if any modifications are made to the loop.
bool formLCSSA(Loop &L, DominatorTree &DT, LoopInfo *LI,
ScalarEvolution *SE = nullptr);
/// \brief Put a loop nest into LCSSA form.
///
/// This recursively forms LCSSA for a loop nest.
///
/// LoopInfo and DominatorTree are required and preserved.
///
/// If ScalarEvolution is passed in, it will be preserved.
///
/// Returns true if any modifications are made to the loop.
bool formLCSSARecursively(Loop &L, DominatorTree &DT, LoopInfo *LI,
ScalarEvolution *SE = nullptr);
}
#endif