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abd43e3a08
Summary: This patch adds isNegative, isNonNegative for querying whether the sign bit is known. It also adds makeNegative and makeNonNegative for controlling the sign bit. Reviewers: RKSimon, spatel, davide Reviewed By: RKSimon Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D32651 llvm-svn: 301747
62 lines
1.7 KiB
C++
62 lines
1.7 KiB
C++
//===- llvm/Support/KnownBits.h - Stores known zeros/ones -------*- 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 a class for representing known zeros and ones used by
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// computeKnownBits.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_KNOWNBITS_H
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#define LLVM_SUPPORT_KNOWNBITS_H
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#include "llvm/ADT/APInt.h"
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namespace llvm {
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// Struct for tracking the known zeros and ones of a value.
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struct KnownBits {
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APInt Zero;
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APInt One;
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// Default construct Zero and One.
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KnownBits() {}
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/// Create a known bits object of BitWidth bits initialized to unknown.
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KnownBits(unsigned BitWidth) : Zero(BitWidth, 0), One(BitWidth, 0) {}
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/// Get the bit width of this value.
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unsigned getBitWidth() const {
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assert(Zero.getBitWidth() == One.getBitWidth() &&
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"Zero and One should have the same width!");
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return Zero.getBitWidth();
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}
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/// Returns true if this value is known to be negative.
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bool isNegative() const { return One.isSignBitSet(); }
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/// Returns true if this value is known to be non-negative.
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bool isNonNegative() const { return Zero.isSignBitSet(); }
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/// Make this value negative.
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void makeNegative() {
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assert(!isNonNegative() && "Can't make a non-negative value negative");
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One.setSignBit();
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}
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/// Make this value negative.
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void makeNonNegative() {
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assert(!isNegative() && "Can't make a negative value non-negative");
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Zero.setSignBit();
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}
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};
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} // end namespace llvm
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#endif
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