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📁 ..
📄 README.md(8.14 KB)
📄 TODO(950 B)
📄 addressingmodes.go(23.64 KB)
📄 bench_test.go(531 B)
📄 biasedsparsemap.go(2.71 KB)
📄 block.go(11.1 KB)
📄 branchelim.go(11.98 KB)
📄 branchelim_test.go(5.21 KB)
📄 cache.go(2.46 KB)
📄 check.go(16.59 KB)
📄 checkbce.go(956 B)
📄 compile.go(18.19 KB)
📄 config.go(11.7 KB)
📄 copyelim.go(1.83 KB)
📄 copyelim_test.go(1.29 KB)
📄 critical.go(3.19 KB)
📄 cse.go(9.43 KB)
📄 cse_test.go(4.25 KB)
📄 deadcode.go(9.61 KB)
📄 deadcode_test.go(3.49 KB)
📄 deadstore.go(9.08 KB)
📄 deadstore_test.go(4.09 KB)
📄 debug.go(56.34 KB)
📄 debug_lines_test.go(8.29 KB)
📄 debug_test.go(28.75 KB)
📄 decompose.go(13.41 KB)
📄 dom.go(7.98 KB)
📄 dom_test.go(13.34 KB)
📄 expand_calls.go(63.5 KB)
📄 export_test.go(3.23 KB)
📄 flagalloc.go(6.68 KB)
📄 flags_amd64_test.s(533 B)
📄 flags_arm64_test.s(699 B)
📄 flags_test.go(2.49 KB)
📄 func.go(27.08 KB)
📄 func_test.go(13.07 KB)
📄 fuse.go(6.5 KB)
📄 fuse_branchredirect.go(3.24 KB)
📄 fuse_comparisons.go(4.04 KB)
📄 fuse_test.go(7.21 KB)
📁 gen
📄 html.go(34.72 KB)
📄 id.go(576 B)
📄 layout.go(4.82 KB)
📄 lca.go(3.77 KB)
📄 lca_test.go(1.65 KB)
📄 likelyadjust.go(15.24 KB)
📄 location.go(3.06 KB)
📄 loopbce.go(10.54 KB)
📄 loopreschedchecks.go(15.86 KB)
📄 looprotate.go(2.61 KB)
📄 lower.go(1.36 KB)
📄 magic.go(15.77 KB)
📄 magic_test.go(9.1 KB)
📄 nilcheck.go(11.06 KB)
📄 nilcheck_test.go(12.17 KB)
📄 numberlines.go(7.83 KB)
📄 op.go(18.65 KB)
📄 opGen.go(1.01 MB)
📄 opt.go(308 B)
📄 passbm_test.go(3.14 KB)
📄 phielim.go(1.48 KB)
📄 phiopt.go(8.08 KB)
📄 poset.go(37.2 KB)
📄 poset_test.go(18.14 KB)
📄 print.go(3.85 KB)
📄 prove.go(41.82 KB)
📄 regalloc.go(83.69 KB)
📄 regalloc_test.go(6.49 KB)
📄 rewrite.go(53.49 KB)
📄 rewrite386.go(289.01 KB)
📄 rewrite386splitload.go(4.05 KB)
📄 rewriteAMD64.go(888.95 KB)
📄 rewriteAMD64splitload.go(21.41 KB)
📄 rewriteARM.go(487.7 KB)
📄 rewriteARM64.go(751.84 KB)
📄 rewriteCond_test.go(10.62 KB)
📄 rewriteLOONG64.go(193.44 KB)
📄 rewriteMIPS.go(174.44 KB)
📄 rewriteMIPS64.go(195.55 KB)
📄 rewritePPC64.go(431.6 KB)
📄 rewriteRISCV64.go(159.66 KB)
📄 rewriteS390X.go(433.4 KB)
📄 rewriteWasm.go(109.86 KB)
📄 rewrite_test.go(6.91 KB)
📄 rewritedec.go(10.16 KB)
📄 rewritedec64.go(63.77 KB)
📄 rewritegeneric.go(617.96 KB)
📄 schedule.go(18.23 KB)
📄 schedule_test.go(2.91 KB)
📄 shift_test.go(4.05 KB)
📄 shortcircuit.go(12.63 KB)
📄 shortcircuit_test.go(1.31 KB)
📄 sizeof_test.go(855 B)
📄 softfloat.go(1.99 KB)
📄 sparsemap.go(1.98 KB)
📄 sparseset.go(1.54 KB)
📄 sparsetree.go(8.05 KB)
📄 stackalloc.go(12.79 KB)
📄 stackframe.go(290 B)
📄 stmtlines_test.go(2.96 KB)
📁 testdata
📄 tighten.go(4.3 KB)
📄 trim.go(4.24 KB)
📄 tuple.go(1.97 KB)
📄 value.go(15.21 KB)
📄 writebarrier.go(19.29 KB)
📄 writebarrier_test.go(1.75 KB)
📄 xposmap.go(3.29 KB)
📄 zcse.go(2.07 KB)
📄 zeroextension_test.go(1.66 KB)

Editing: lca.go

// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

import (
	"math/bits"
)

// Code to compute lowest common ancestors in the dominator tree.
// https://en.wikipedia.org/wiki/Lowest_common_ancestor
// https://en.wikipedia.org/wiki/Range_minimum_query#Solution_using_constant_time_and_linearithmic_space

// lcaRange is a data structure that can compute lowest common ancestor queries
// in O(n lg n) precomputed space and O(1) time per query.
type lcaRange struct {
	// Additional information about each block (indexed by block ID).
	blocks []lcaRangeBlock

// Data structure for range minimum queries.
	// rangeMin[k][i] contains the ID of the minimum depth block
	// in the Euler tour from positions i to i+1<<k-1, inclusive.
	rangeMin [][]ID
}

type lcaRangeBlock struct {
	b          *Block
	parent     ID    // parent in dominator tree.  0 = no parent (entry or unreachable)
	firstChild ID    // first child in dominator tree
	sibling    ID    // next child of parent
	pos        int32 // an index in the Euler tour where this block appears (any one of its occurrences)
	depth      int32 // depth in dominator tree (root=0, its children=1, etc.)
}

func makeLCArange(f *Func) *lcaRange {
	dom := f.Idom()

// Build tree
	blocks := make([]lcaRangeBlock, f.NumBlocks())
	for _, b := range f.Blocks {
		blocks[b.ID].b = b
		if dom[b.ID] == nil {
			continue // entry or unreachable
		}
		parent := dom[b.ID].ID
		blocks[b.ID].parent = parent
		blocks[b.ID].sibling = blocks[parent].firstChild
		blocks[parent].firstChild = b.ID
	}

// Compute euler tour ordering.
	// Each reachable block will appear #children+1 times in the tour.
	tour := make([]ID, 0, f.NumBlocks()*2-1)
	type queueEntry struct {
		bid ID // block to work on
		cid ID // child we're already working on (0 = haven't started yet)
	}
	q := []queueEntry{{f.Entry.ID, 0}}
	for len(q) > 0 {
		n := len(q) - 1
		bid := q[n].bid
		cid := q[n].cid
		q = q[:n]

// Add block to tour.
		blocks[bid].pos = int32(len(tour))
		tour = append(tour, bid)

// Proceed down next child edge (if any).
		if cid == 0 {
			// This is our first visit to b. Set its depth.
			blocks[bid].depth = blocks[blocks[bid].parent].depth + 1
			// Then explore its first child.
			cid = blocks[bid].firstChild
		} else {
			// We've seen b before. Explore the next child.
			cid = blocks[cid].sibling
		}
		if cid != 0 {
			q = append(q, queueEntry{bid, cid}, queueEntry{cid, 0})
		}
	}

// Compute fast range-minimum query data structure
	rangeMin := make([][]ID, 0, bits.Len64(uint64(len(tour))))
	rangeMin = append(rangeMin, tour) // 1-size windows are just the tour itself.
	for logS, s := 1, 2; s < len(tour); logS, s = logS+1, s*2 {
		r := make([]ID, len(tour)-s+1)
		for i := 0; i < len(tour)-s+1; i++ {
			bid := rangeMin[logS-1][i]
			bid2 := rangeMin[logS-1][i+s/2]
			if blocks[bid2].depth < blocks[bid].depth {
				bid = bid2
			}
			r[i] = bid
		}
		rangeMin = append(rangeMin, r)
	}

return &lcaRange{blocks: blocks, rangeMin: rangeMin}
}

// find returns the lowest common ancestor of a and b.
func (lca *lcaRange) find(a, b *Block) *Block {
	if a == b {
		return a
	}
	// Find the positions of a and bin the Euler tour.
	p1 := lca.blocks[a.ID].pos
	p2 := lca.blocks[b.ID].pos
	if p1 > p2 {
		p1, p2 = p2, p1
	}

// The lowest common ancestor is the minimum depth block
	// on the tour from p1 to p2.  We've precomputed minimum
	// depth blocks for powers-of-two subsequences of the tour.
	// Combine the right two precomputed values to get the answer.
	logS := uint(log64(int64(p2 - p1)))
	bid1 := lca.rangeMin[logS][p1]
	bid2 := lca.rangeMin[logS][p2-1<<logS+1]
	if lca.blocks[bid1].depth < lca.blocks[bid2].depth {
		return lca.blocks[bid1].b
	}
	return lca.blocks[bid2].b
}

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Editing: lca.go

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