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2c7c54c86c
In order to enable the preservation of noalias function parameter information after inlining, and the representation of block-level __restrict__ pointer information (etc.), additional kinds of aliasing metadata will be introduced. This metadata needs to be carried around in AliasAnalysis::Location objects (and MMOs at the SDAG level), and so we need to generalize the current scheme (which is hard-coded to just one TBAA MDNode*). This commit introduces only the necessary refactoring to allow for the introduction of other aliasing metadata types, but does not actually introduce any (that will come in a follow-up commit). What it does introduce is a new AAMDNodes structure to hold all of the aliasing metadata nodes associated with a particular memory-accessing instruction, and uses that structure instead of the raw MDNode* in AliasAnalysis::Location, etc. No functionality change intended. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213859 91177308-0d34-0410-b5e6-96231b3b80d8
59 lines
2.4 KiB
C++
59 lines
2.4 KiB
C++
//===- Loads.h - Local load analysis --------------------------------------===//
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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 declares simple local analyses for load instructions.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_LOADS_H
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#define LLVM_ANALYSIS_LOADS_H
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#include "llvm/IR/BasicBlock.h"
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namespace llvm {
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class AliasAnalysis;
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class DataLayout;
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class MDNode;
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/// isSafeToLoadUnconditionally - Return true if we know that executing a load
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/// from this value cannot trap. If it is not obviously safe to load from the
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/// specified pointer, we do a quick local scan of the basic block containing
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/// ScanFrom, to determine if the address is already accessed.
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bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom,
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unsigned Align,
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const DataLayout *TD = nullptr);
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/// FindAvailableLoadedValue - Scan the ScanBB block backwards (starting at
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/// the instruction before ScanFrom) checking to see if we have the value at
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/// the memory address *Ptr locally available within a small number of
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/// instructions. If the value is available, return it.
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///
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/// If not, return the iterator for the last validated instruction that the
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/// value would be live through. If we scanned the entire block and didn't
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/// find something that invalidates *Ptr or provides it, ScanFrom would be
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/// left at begin() and this returns null. ScanFrom could also be left
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///
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/// MaxInstsToScan specifies the maximum instructions to scan in the block.
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/// If it is set to 0, it will scan the whole block. You can also optionally
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/// specify an alias analysis implementation, which makes this more precise.
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///
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/// If AATags is non-null and a load or store is found, the AA tags from the
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/// load or store are recorded there. If there are no AA tags or if no access
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/// is found, it is left unmodified.
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Value *FindAvailableLoadedValue(Value *Ptr, BasicBlock *ScanBB,
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BasicBlock::iterator &ScanFrom,
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unsigned MaxInstsToScan = 6,
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AliasAnalysis *AA = nullptr,
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AAMDNodes *AATags = nullptr);
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}
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#endif
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