1 //===- Loads.h - Local load analysis --------------------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file declares simple local analyses for load instructions. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_ANALYSIS_LOADS_H 15 #define LLVM_ANALYSIS_LOADS_H 16 17 #include "llvm/BasicBlock.h" 18 19 namespace llvm { 20 21 class AliasAnalysis; 22 class TargetData; 23 24 /// isSafeToLoadUnconditionally - Return true if we know that executing a load 25 /// from this value cannot trap. If it is not obviously safe to load from the 26 /// specified pointer, we do a quick local scan of the basic block containing 27 /// ScanFrom, to determine if the address is already accessed. 28 bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom, 29 unsigned Align, const TargetData *TD = 0); 30 31 /// FindAvailableLoadedValue - Scan the ScanBB block backwards (starting at 32 /// the instruction before ScanFrom) checking to see if we have the value at 33 /// the memory address *Ptr locally available within a small number of 34 /// instructions. If the value is available, return it. 35 /// 36 /// If not, return the iterator for the last validated instruction that the 37 /// value would be live through. If we scanned the entire block and didn't 38 /// find something that invalidates *Ptr or provides it, ScanFrom would be 39 /// left at begin() and this returns null. ScanFrom could also be left 40 /// 41 /// MaxInstsToScan specifies the maximum instructions to scan in the block. 42 /// If it is set to 0, it will scan the whole block. You can also optionally 43 /// specify an alias analysis implementation, which makes this more precise. 44 Value *FindAvailableLoadedValue(Value *Ptr, BasicBlock *ScanBB, 45 BasicBlock::iterator &ScanFrom, 46 unsigned MaxInstsToScan = 6, 47 AliasAnalysis *AA = 0); 48 49 } 50 51 #endif 52
