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e8714301ce
We can reuse this code with other div/rem transforms as shown in: https://reviews.llvm.org/D31037 https://bugs.llvm.org/show_bug.cgi?id=31028 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311661 91177308-0d34-0410-b5e6-96231b3b80d8
67 lines
2.2 KiB
C++
67 lines
2.2 KiB
C++
//===- llvm/Transforms/Utils/BypassSlowDivision.h --------------*- 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 contains an optimization for div and rem on architectures that
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// execute short instructions significantly faster than longer instructions.
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// For example, on Intel Atom 32-bit divides are slow enough that during
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// runtime it is profitable to check the value of the operands, and if they are
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// positive and less than 256 use an unsigned 8-bit divide.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TRANSFORMS_UTILS_BYPASSSLOWDIVISION_H
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#define LLVM_TRANSFORMS_UTILS_BYPASSSLOWDIVISION_H
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/IR/Function.h"
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namespace llvm {
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struct DivRemMapKey {
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bool SignedOp;
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Value *Dividend;
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Value *Divisor;
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DivRemMapKey(bool InSignedOp, Value *InDividend, Value *InDivisor)
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: SignedOp(InSignedOp), Dividend(InDividend), Divisor(InDivisor) {}
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};
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template <> struct DenseMapInfo<DivRemMapKey> {
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static bool isEqual(const DivRemMapKey &Val1, const DivRemMapKey &Val2) {
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return Val1.SignedOp == Val2.SignedOp && Val1.Dividend == Val2.Dividend &&
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Val1.Divisor == Val2.Divisor;
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}
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static DivRemMapKey getEmptyKey() {
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return DivRemMapKey(false, nullptr, nullptr);
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}
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static DivRemMapKey getTombstoneKey() {
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return DivRemMapKey(true, nullptr, nullptr);
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}
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static unsigned getHashValue(const DivRemMapKey &Val) {
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return (unsigned)(reinterpret_cast<uintptr_t>(Val.Dividend) ^
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reinterpret_cast<uintptr_t>(Val.Divisor)) ^
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(unsigned)Val.SignedOp;
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}
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};
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/// This optimization identifies DIV instructions in a BB that can be
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/// profitably bypassed and carried out with a shorter, faster divide.
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///
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/// This optimization may add basic blocks immediately after BB; for obvious
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/// reasons, you shouldn't pass those blocks to bypassSlowDivision.
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bool bypassSlowDivision(
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BasicBlock *BB, const DenseMap<unsigned int, unsigned int> &BypassWidth);
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} // End llvm namespace
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#endif
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