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/* Source code for RCC-Legacy.
Copyright (C) 2026 Richard Qin
This file is part of RCC.
RCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
RCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with RCC; see the file LICENSE. If not see
<http://www.gnu.org/licenses/>. */
/// @file loopinfo.h
/// @brief Natural loop and constant BIV identification.
#pragma once
#include "rcc/all.h"
#include <unordered_set>
#include <vector>
namespace rcc {
struct Loop {
Blk* header;
Blk* preheader;
Blk* latch;
std::vector<Blk*> body; // Includes header / latch
std::unordered_set<uint> body_bid; // Set of b->id in body, used for tmp.bid lookup
};
/// Constant Basic Induction Variable.
struct Biv {
Ref to; // header phi.to
int cls; // phi cls
int64_t init; // Preheader constant
int64_t step; // Constant step of Oadd at latch, != 0
};
void find_loops(Fn*, std::vector<Loop>&);
void detect_bivs(Fn*, const Loop&, std::vector<Biv>&);
/// Decode CBits constant Ref (integer). Returns false for CAddr / float / non-RCon.
bool ref_is_const(Fn*, Ref, int64_t& out);
/// Get defining Ins via Tmp::def. Returns nullptr for non-RTmp or out of bounds.
Ins* def_ins(Fn*, Ref);
/// Canonical pointer IV after LSR.
struct PointerIV {
Ref phi_to;
Ref base;
Ref next;
int64_t step;
};
/// Identify pointer IV on header phi. Returns false on failure.
bool pick_pointer_iv(Fn*, const Loop&, Phi*, PointerIV*);
/// Match pointer termination condition against pointer IV.
bool check_exit_cmp(Fn*, const Loop&, Ref p, Ref* end_out, Blk** after_out);
/// Check if any def inside the loop is used by outside users.
bool has_outside_use(Fn*, const Loop&);
} // namespace rcc
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