1// Copyright 2023 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
5package inlheur
6
7import (
8	"cmd/compile/internal/base"
9	"cmd/compile/internal/ir"
10	"cmd/internal/src"
11	"fmt"
12	"io"
13	"path/filepath"
14	"sort"
15	"strings"
16)
17
18// CallSite records useful information about a potentially inlinable
19// (direct) function call. "Callee" is the target of the call, "Call"
20// is the ir node corresponding to the call itself, "Assign" is
21// the top-level assignment statement containing the call (if the call
22// appears in the form of a top-level statement, e.g. "x := foo()"),
23// "Flags" contains properties of the call that might be useful for
24// making inlining decisions, "Score" is the final score assigned to
25// the site, and "ID" is a numeric ID for the site within its
26// containing function.
27type CallSite struct {
28	Callee *ir.Func
29	Call   *ir.CallExpr
30	parent *CallSite
31	Assign ir.Node
32	Flags  CSPropBits
33
34	ArgProps  []ActualExprPropBits
35	Score     int
36	ScoreMask scoreAdjustTyp
37	ID        uint
38	aux       uint8
39}
40
41// CallSiteTab is a table of call sites, keyed by call expr.
42// Ideally it would be nice to key the table by src.XPos, but
43// this results in collisions for calls on very long lines (the
44// front end saturates column numbers at 255). We also wind up
45// with many calls that share the same auto-generated pos.
46type CallSiteTab map[*ir.CallExpr]*CallSite
47
48// ActualExprPropBits describes a property of an actual expression (value
49// passed to some specific func argument at a call site).
50type ActualExprPropBits uint8
51
52const (
53	ActualExprConstant ActualExprPropBits = 1 << iota
54	ActualExprIsConcreteConvIface
55	ActualExprIsFunc
56	ActualExprIsInlinableFunc
57)
58
59type CSPropBits uint32
60
61const (
62	CallSiteInLoop CSPropBits = 1 << iota
63	CallSiteOnPanicPath
64	CallSiteInInitFunc
65)
66
67type csAuxBits uint8
68
69const (
70	csAuxInlined = 1 << iota
71)
72
73// encodedCallSiteTab is a table keyed by "encoded" callsite
74// (stringified src.XPos plus call site ID) mapping to a value of call
75// property bits and score.
76type encodedCallSiteTab map[string]propsAndScore
77
78type propsAndScore struct {
79	props CSPropBits
80	score int
81	mask  scoreAdjustTyp
82}
83
84func (pas propsAndScore) String() string {
85	return fmt.Sprintf("P=%s|S=%d|M=%s", pas.props.String(),
86		pas.score, pas.mask.String())
87}
88
89func (cst CallSiteTab) merge(other CallSiteTab) error {
90	for k, v := range other {
91		if prev, ok := cst[k]; ok {
92			return fmt.Errorf("internal error: collision during call site table merge, fn=%s callsite=%s", prev.Callee.Sym().Name, fmtFullPos(prev.Call.Pos()))
93		}
94		cst[k] = v
95	}
96	return nil
97}
98
99func fmtFullPos(p src.XPos) string {
100	var sb strings.Builder
101	sep := ""
102	base.Ctxt.AllPos(p, func(pos src.Pos) {
103		fmt.Fprintf(&sb, sep)
104		sep = "|"
105		file := filepath.Base(pos.Filename())
106		fmt.Fprintf(&sb, "%s:%d:%d", file, pos.Line(), pos.Col())
107	})
108	return sb.String()
109}
110
111func EncodeCallSiteKey(cs *CallSite) string {
112	var sb strings.Builder
113	// FIXME: maybe rewrite line offsets relative to function start?
114	sb.WriteString(fmtFullPos(cs.Call.Pos()))
115	fmt.Fprintf(&sb, "|%d", cs.ID)
116	return sb.String()
117}
118
119func buildEncodedCallSiteTab(tab CallSiteTab) encodedCallSiteTab {
120	r := make(encodedCallSiteTab)
121	for _, cs := range tab {
122		k := EncodeCallSiteKey(cs)
123		r[k] = propsAndScore{
124			props: cs.Flags,
125			score: cs.Score,
126			mask:  cs.ScoreMask,
127		}
128	}
129	return r
130}
131
132// dumpCallSiteComments emits comments into the dump file for the
133// callsites in the function of interest. If "ecst" is non-nil, we use
134// that, otherwise generated a fresh encodedCallSiteTab from "tab".
135func dumpCallSiteComments(w io.Writer, tab CallSiteTab, ecst encodedCallSiteTab) {
136	if ecst == nil {
137		ecst = buildEncodedCallSiteTab(tab)
138	}
139	tags := make([]string, 0, len(ecst))
140	for k := range ecst {
141		tags = append(tags, k)
142	}
143	sort.Strings(tags)
144	for _, s := range tags {
145		v := ecst[s]
146		fmt.Fprintf(w, "// callsite: %s flagstr %q flagval %d score %d mask %d maskstr %q\n", s, v.props.String(), v.props, v.score, v.mask, v.mask.String())
147	}
148	fmt.Fprintf(w, "// %s\n", csDelimiter)
149}
150