//===-- HexagonHardwareLoops.cpp - Identify and generate hardware loops ---===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass identifies loops where we can generate the Hexagon hardware
// loop instruction. The hardware loop can perform loop branches with a
// zero-cycle overhead.
//
// The pattern that defines the induction variable can changed depending on
// prior optimizations. For example, the IndVarSimplify phase run by 'opt'
// normalizes induction variables, and the Loop Strength Reduction pass
// run by 'llc' may also make changes to the induction variable.
// The pattern detected by this phase is due to running Strength Reduction.
//
// Criteria for hardware loops:
// - Countable loops (w/ ind. var for a trip count)
// - Assumes loops are normalized by IndVarSimplify
// - Try inner-most loops first
// - No nested hardware loops.
// - No function calls in loops.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "hwloops"<
