mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2024-10-24 13:33:37 +02:00
d160a578e0
As noted in https://reviews.llvm.org/D22537 , we can use this functionality in visitSelectInstWithICmp() and InstSimplify, but currently we have duplicated code. llvm-svn: 276140
71 lines
2.5 KiB
C++
71 lines
2.5 KiB
C++
//===-- CmpInstAnalysis.h - Utils to help fold compare insts ----*- C++ -*-===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file holds routines to help analyse compare instructions
|
|
// and fold them into constants or other compare instructions
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_TRANSFORMS_UTILS_CMPINSTANALYSIS_H
|
|
#define LLVM_TRANSFORMS_UTILS_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, which turns an opcode and two
|
|
/// operands into either a constant true or false, or the predicate for a new
|
|
/// ICmp instruction. 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 for which is output
|
|
/// in NewICmpPred.
|
|
Value *getICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS,
|
|
CmpInst::Predicate &NewICmpPred);
|
|
|
|
/// 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 & Y) pred Z) if possible. The returned
|
|
/// predicate is either == or !=. Returns false if decomposition fails.
|
|
bool decomposeBitTestICmp(const ICmpInst *I, CmpInst::Predicate &Pred,
|
|
Value *&X, Value *&Y, Value *&Z);
|
|
|
|
} // end namespace llvm
|
|
|
|
#endif
|