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1 | //===- llvm/Transforms/Utils/BypassSlowDivision.h --------------*- C++ -*-===// |
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 contains an optimization for div and rem on architectures that | |
11 | // execute short instructions significantly faster than longer instructions. | |
12 | // For example, on Intel Atom 32-bit divides are slow enough that during | |
13 | // runtime it is profitable to check the value of the operands, and if they are | |
14 | // positive and less than 256 use an unsigned 8-bit divide. | |
15 | // | |
16 | //===----------------------------------------------------------------------===// | |
17 | ||
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18 | #ifndef LLVM_TRANSFORMS_UTILS_BYPASSSLOWDIVISION_H |
19 | #define LLVM_TRANSFORMS_UTILS_BYPASSSLOWDIVISION_H | |
223e47cc | 20 | |
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21 | #include "llvm/ADT/DenseMap.h" |
22 | #include "llvm/IR/Function.h" | |
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23 | |
24 | namespace llvm { | |
25 | ||
26 | /// This optimization identifies DIV instructions that can be | |
27 | /// profitably bypassed and carried out with a shorter, faster divide. | |
28 | bool bypassSlowDivision(Function &F, | |
29 | Function::iterator &I, | |
970d7e83 | 30 | const DenseMap<unsigned int, unsigned int> &BypassWidth); |
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31 | |
32 | } // End llvm namespace | |
33 | ||
34 | #endif |