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name	port-library-options
description	Port an llvm/lib/XXX library's cl::opt globals to a TableGen OptionsStruct (RFC 91877, LibraryOptions.td). Use when migrating a library's options, reviewing such a port, or writing its .td.

Porting a library's cl::opts to an OptionsStruct

Field kinds are documented in "Declaring a Library's Options in TableGen" (llvm/docs/CommandLine.md). Reference ports: CGData (lib/CGData/CGDataOptions.*), InstCombine (InstCombineCLOptions.*), CodeGen (lib/CodeGen/CodeGenOptions.*), Sparc (a target), IR (lib/IR/IROptions.*, no central object).

1. Survey

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From 822ab47500b62fac9647f8360b2b9af87ddf8201 Mon Sep 17 00:00:00 2001
From: Fangrui Song <hidden>
Date: Sun, 20 Sep 2026 12:35:19 -0700
Subject: [PATCH] [Option] Declare a library's command line options in
 TableGen, one struct per library

RFC: https://discourse.llvm.org/t/91877

A library declares its options in a .td file beside its sources:

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From c29fbaee28ba8399fd5225a974c7333048fc5195 Mon Sep 17 00:00:00 2001
From: Fangrui Song <hidden>
Date: Wed, 17 Jun 2026 23:28:54 -0700
Subject: [PATCH] [ELF] Parallelize input file parsing and symbol resolution
 (order-independent extraction)

Replace the serial elf::parseFiles loop with a parallel pipeline. Per
batch the pipeline reads symbol records (parallel per file,
counting-sorted into 32 hash buckets), builds a per-bucket name
database, activates archive members, creates and resolves symbols

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Simplified BranchProbabilityInfo demo

bpi.cpp reimplements the estimated (loop-aware) heuristic of LLVM's BranchProbabilityInfo — the only heuristic that is a pure function of the CFG + loop structure. See the header comment in bpi.cpp for what is intentionally omitted (instruction-level heuristics, computeUnlikelySuccessors).

Loops come from a nested cycle forest built with Tao Wei's single-pass DFS (the algorithm llvm::CycleInfo uses), visiting successors LIFO to match LLVM's iterative DFS order. This handles reducible and irreducible loops and gives each

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// Havlak-Tarjan loop-nesting-forest algorithm, self-contained.
//
// Two passes over the CFG: (1) a DFS spanning tree recording preorder and finish
// times, then (2) candidate headers in reverse preorder, each flood-filling its
// loop body backward through predecessors, with a UNION-FIND collapse of the
// already-formed inner loops. Each loop tracks its ENTRY set, so absorbing an
// irreducible multi-entry subloop re-examines the predecessors of ALL its
// entries -- pulling in the outer nodes that reach it through a non-header
// entry. It builds the same loop-nesting forest as the single-pass wei.cpp and
// as llvm/include/llvm/ADT/GenericCycleImpl.h.

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// ============================================================================
//  Squarebound · 方格征途
//  —— 致童年：在五子棋盘上，用黑白棋子与四色标识摆出的战棋梦。
//
//  绿子=主角  蓝/红/黄=英雄  白子正面=我方小兵  白子反面=敌方小兵  黑子=障碍
//  15x15 棋盘（五子棋规格，含星位）。英雄血量以二进制棋子展示（致敬）。
//
//  操作：左键 选择/移动/攻击   右键 待命/取消   空格 结束回合(敌方回合按住加速)
//        Shift+F1~F9 存档     F1~F9 读档       Esc 取消选择/返回标题
// ============================================================================

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Alan Modra - Code Review Style
===============================

Role: Long-time GNU binutils maintainer, GNU ld (BFD linker), PowerPC backend

Deep institutional knowledge
- Decades of binutils/ld experience
- Knows the history behind obscure design decisions
- Understands BFD internals better than anyone

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#include <algorithm>
#include <cassert>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <numeric>
#include <random>
#include <vector>
using namespace std;

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#include <assert.h>
#include <inttypes.h>
#include <stdbit.h>
#include <stdio.h>
#include <string.h>

/*
Big-endian prefix varint encoding for 64-bit integers.

The first byte determines the total length using most significant bits.

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