1234285Sdim//===-- CmpInstAnalysis.h - Utils to help fold compare insts ------===// 2234285Sdim// 3234285Sdim// The LLVM Compiler Infrastructure 4234285Sdim// 5234285Sdim// This file is distributed under the University of Illinois Open Source 6234285Sdim// License. See LICENSE.TXT for details. 7234285Sdim// 8234285Sdim//===----------------------------------------------------------------------===// 9234285Sdim// 10234285Sdim// This file holds routines to help analyse compare instructions 11234285Sdim// and fold them into constants or other compare instructions 12234285Sdim// 13234285Sdim//===----------------------------------------------------------------------===// 14234285Sdim 15234285Sdim#ifndef LLVM_TRANSFORMS_UTILS_CMPINSTANALYSIS_H 16234285Sdim#define LLVM_TRANSFORMS_UTILS_CMPINSTANALYSIS_H 17234285Sdim 18249423Sdim#include "llvm/IR/InstrTypes.h" 19234285Sdim 20234285Sdimnamespace llvm { 21234285Sdim class ICmpInst; 22234285Sdim class Value; 23234285Sdim 24234285Sdim /// getICmpCode - Encode a icmp predicate into a three bit mask. These bits 25234285Sdim /// are carefully arranged to allow folding of expressions such as: 26234285Sdim /// 27234285Sdim /// (A < B) | (A > B) --> (A != B) 28234285Sdim /// 29234285Sdim /// Note that this is only valid if the first and second predicates have the 30234285Sdim /// same sign. Is illegal to do: (A u< B) | (A s> B) 31234285Sdim /// 32234285Sdim /// Three bits are used to represent the condition, as follows: 33234285Sdim /// 0 A > B 34234285Sdim /// 1 A == B 35234285Sdim /// 2 A < B 36234285Sdim /// 37234285Sdim /// <=> Value Definition 38234285Sdim /// 000 0 Always false 39234285Sdim /// 001 1 A > B 40234285Sdim /// 010 2 A == B 41234285Sdim /// 011 3 A >= B 42234285Sdim /// 100 4 A < B 43234285Sdim /// 101 5 A != B 44234285Sdim /// 110 6 A <= B 45234285Sdim /// 111 7 Always true 46234285Sdim /// 47234285Sdim unsigned getICmpCode(const ICmpInst *ICI, bool InvertPred = false); 48234285Sdim 49234285Sdim /// getICmpValue - This is the complement of getICmpCode, which turns an 50234285Sdim /// opcode and two operands into either a constant true or false, or the 51234285Sdim /// predicate for a new ICmp instruction. The sign is passed in to determine 52234285Sdim /// which kind of predicate to use in the new icmp instruction. 53234285Sdim /// Non-NULL return value will be a true or false constant. 54234285Sdim /// NULL return means a new ICmp is needed. The predicate for which is 55234285Sdim /// output in NewICmpPred. 56234285Sdim Value *getICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS, 57234285Sdim CmpInst::Predicate &NewICmpPred); 58234285Sdim 59234285Sdim /// PredicatesFoldable - Return true if both predicates match sign or if at 60234285Sdim /// least one of them is an equality comparison (which is signless). 61234285Sdim bool PredicatesFoldable(CmpInst::Predicate p1, CmpInst::Predicate p2); 62234285Sdim 63234285Sdim} // end namespace llvm 64234285Sdim 65234285Sdim#endif 66234285Sdim 67