Source file src/pkg/cmd/compile/internal/ssa/xposmap.go

     1	// Copyright 2019 The Go Authors. All rights reserved.
     2	// Use of this source code is governed by a BSD-style
     3	// license that can be found in the LICENSE file.
     4	
     5	package ssa
     6	
     7	import (
     8		"cmd/internal/src"
     9		"fmt"
    10	)
    11	
    12	type lineRange struct {
    13		first, last uint32
    14	}
    15	
    16	// An xposmap is a map from fileindex and line of src.XPos to int32,
    17	// implemented sparsely to save space (column and statement status are ignored).
    18	// The sparse skeleton is constructed once, and then reused by ssa phases
    19	// that (re)move values with statements attached.
    20	type xposmap struct {
    21		// A map from file index to maps from line range to integers (block numbers)
    22		maps map[int32]*biasedSparseMap
    23		// The next two fields provide a single-item cache for common case of repeated lines from same file.
    24		lastIndex int32            // -1 means no entry in cache
    25		lastMap   *biasedSparseMap // map found at maps[lastIndex]
    26	}
    27	
    28	// newXposmap constructs an xposmap valid for inputs which have a file index in the keys of x,
    29	// and line numbers in the range x[file index].
    30	// The resulting xposmap will panic if a caller attempts to set or add an XPos not in that range.
    31	func newXposmap(x map[int]lineRange) *xposmap {
    32		maps := make(map[int32]*biasedSparseMap)
    33		for i, p := range x {
    34			maps[int32(i)] = newBiasedSparseMap(int(p.first), int(p.last))
    35		}
    36		return &xposmap{maps: maps, lastIndex: -1} // zero for the rest is okay
    37	}
    38	
    39	// clear removes data from the map but leaves the sparse skeleton.
    40	func (m *xposmap) clear() {
    41		for _, l := range m.maps {
    42			if l != nil {
    43				l.clear()
    44			}
    45		}
    46		m.lastIndex = -1
    47		m.lastMap = nil
    48	}
    49	
    50	// mapFor returns the line range map for a given file index.
    51	func (m *xposmap) mapFor(index int32) *biasedSparseMap {
    52		if index == m.lastIndex {
    53			return m.lastMap
    54		}
    55		mf := m.maps[index]
    56		m.lastIndex = index
    57		m.lastMap = mf
    58		return mf
    59	}
    60	
    61	// set inserts p->v into the map.
    62	// If p does not fall within the set of fileindex->lineRange used to construct m, this will panic.
    63	func (m *xposmap) set(p src.XPos, v int32) {
    64		s := m.mapFor(p.FileIndex())
    65		if s == nil {
    66			panic(fmt.Sprintf("xposmap.set(%d), file index not found in map\n", p.FileIndex()))
    67		}
    68		s.set(p.Line(), v)
    69	}
    70	
    71	// get returns the int32 associated with the file index and line of p.
    72	func (m *xposmap) get(p src.XPos) int32 {
    73		s := m.mapFor(p.FileIndex())
    74		if s == nil {
    75			return -1
    76		}
    77		return s.get(p.Line())
    78	}
    79	
    80	// add adds p to m, treating m as a set instead of as a map.
    81	// If p does not fall within the set of fileindex->lineRange used to construct m, this will panic.
    82	// Use clear() in between set/map interpretations of m.
    83	func (m *xposmap) add(p src.XPos) {
    84		m.set(p, 0)
    85	}
    86	
    87	// contains returns whether the file index and line of p are in m,
    88	// treating m as a set instead of as a map.
    89	func (m *xposmap) contains(p src.XPos) bool {
    90		s := m.mapFor(p.FileIndex())
    91		if s == nil {
    92			return false
    93		}
    94		return s.contains(p.Line())
    95	}
    96	
    97	// remove removes the file index and line for p from m,
    98	// whether m is currently treated as a map or set.
    99	func (m *xposmap) remove(p src.XPos) {
   100		s := m.mapFor(p.FileIndex())
   101		if s == nil {
   102			return
   103		}
   104		s.remove(p.Line())
   105	}
   106	
   107	// foreachEntry applies f to each (fileindex, line, value) triple in m.
   108	func (m *xposmap) foreachEntry(f func(j int32, l uint, v int32)) {
   109		for j, mm := range m.maps {
   110			s := mm.size()
   111			for i := 0; i < s; i++ {
   112				l, v := mm.getEntry(i)
   113				f(j, l, v)
   114			}
   115		}
   116	}
   117	

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