mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2024-11-22 10:42:39 +01:00
ae65e281f3
to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
71 lines
2.6 KiB
C++
71 lines
2.6 KiB
C++
//===-- CmpInstAnalysis.h - Utils to help fold compare insts ----*- C++ -*-===//
|
|
//
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file holds routines to help analyse compare instructions
|
|
// and fold them into constants or other compare instructions
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_ANALYSIS_CMPINSTANALYSIS_H
|
|
#define LLVM_ANALYSIS_CMPINSTANALYSIS_H
|
|
|
|
#include "llvm/IR/InstrTypes.h"
|
|
|
|
namespace llvm {
|
|
class ICmpInst;
|
|
class Value;
|
|
|
|
/// Encode a icmp predicate into a three bit mask. These bits are carefully
|
|
/// arranged to allow folding of expressions such as:
|
|
///
|
|
/// (A < B) | (A > B) --> (A != B)
|
|
///
|
|
/// Note that this is only valid if the first and second predicates have the
|
|
/// same sign. It is illegal to do: (A u< B) | (A s> B)
|
|
///
|
|
/// Three bits are used to represent the condition, as follows:
|
|
/// 0 A > B
|
|
/// 1 A == B
|
|
/// 2 A < B
|
|
///
|
|
/// <=> Value Definition
|
|
/// 000 0 Always false
|
|
/// 001 1 A > B
|
|
/// 010 2 A == B
|
|
/// 011 3 A >= B
|
|
/// 100 4 A < B
|
|
/// 101 5 A != B
|
|
/// 110 6 A <= B
|
|
/// 111 7 Always true
|
|
///
|
|
unsigned getICmpCode(const ICmpInst *ICI, bool InvertPred = false);
|
|
|
|
/// This is the complement of getICmpCode. It turns a predicate code into
|
|
/// either a constant true or false or the predicate for a new ICmp.
|
|
/// The sign is passed in to determine which kind of predicate to use in the
|
|
/// new ICmp instruction.
|
|
/// Non-NULL return value will be a true or false constant.
|
|
/// NULL return means a new ICmp is needed. The predicate is output in Pred.
|
|
Constant *getPredForICmpCode(unsigned Code, bool Sign, Type *OpTy,
|
|
CmpInst::Predicate &Pred);
|
|
|
|
/// Return true if both predicates match sign or if at least one of them is an
|
|
/// equality comparison (which is signless).
|
|
bool predicatesFoldable(CmpInst::Predicate P1, CmpInst::Predicate P2);
|
|
|
|
/// Decompose an icmp into the form ((X & Mask) pred 0) if possible. The
|
|
/// returned predicate is either == or !=. Returns false if decomposition
|
|
/// fails.
|
|
bool decomposeBitTestICmp(Value *LHS, Value *RHS, CmpInst::Predicate &Pred,
|
|
Value *&X, APInt &Mask,
|
|
bool LookThroughTrunc = true);
|
|
|
|
} // end namespace llvm
|
|
|
|
#endif
|