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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51864 91177308-0d34-0410-b5e6-96231b3b80d8
56 lines
2.1 KiB
C++
56 lines
2.1 KiB
C++
//===- llvm/Analysis/ValueTracking.h - Walk computations --------*- 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 routines that help analyze properties that chains of
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// computations have.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_VALUETRACKING_H
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#define LLVM_ANALYSIS_VALUETRACKING_H
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namespace llvm {
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class Value;
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class APInt;
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class TargetData;
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/// ComputeMaskedBits - Determine which of the bits specified in Mask are
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/// known to be either zero or one and return them in the KnownZero/KnownOne
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/// bit sets. This code only analyzes bits in Mask, in order to short-circuit
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/// processing.
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void ComputeMaskedBits(Value *V, const APInt &Mask, APInt &KnownZero,
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APInt &KnownOne, TargetData *TD = 0,
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unsigned Depth = 0);
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/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
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/// this predicate to simplify operations downstream. Mask is known to be
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/// zero for bits that V cannot have.
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bool MaskedValueIsZero(Value *V, const APInt &Mask,
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TargetData *TD = 0, unsigned Depth = 0);
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/// ComputeNumSignBits - Return the number of times the sign bit of the
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/// register is replicated into the other bits. We know that at least 1 bit
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/// is always equal to the sign bit (itself), but other cases can give us
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/// information. For example, immediately after an "ashr X, 2", we know that
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/// the top 3 bits are all equal to each other, so we return 3.
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///
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/// 'Op' must have a scalar integer type.
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///
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unsigned ComputeNumSignBits(Value *Op, TargetData *TD = 0,
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unsigned Depth = 0);
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/// CannotBeNegativeZero - Return true if we can prove that the specified FP
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/// value is never equal to -0.0.
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///
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bool CannotBeNegativeZero(const Value *V, unsigned Depth = 0);
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} // end namespace llvm
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#endif
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