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131 lines
4 KiB
Go
131 lines
4 KiB
Go
// Copyright 2017 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package obj
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import "github.com/twitchyliquid64/golang-asm/src"
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// InlTree is a collection of inlined calls. The Parent field of an
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// InlinedCall is the index of another InlinedCall in InlTree.
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//
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// The compiler maintains a global inlining tree and adds a node to it
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// every time a function is inlined. For example, suppose f() calls g()
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// and g has two calls to h(), and that f, g, and h are inlineable:
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//
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// 1 func main() {
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// 2 f()
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// 3 }
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// 4 func f() {
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// 5 g()
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// 6 }
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// 7 func g() {
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// 8 h()
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// 9 h()
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// 10 }
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// 11 func h() {
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// 12 println("H")
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// 13 }
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//
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// Assuming the global tree starts empty, inlining will produce the
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// following tree:
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//
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// []InlinedCall{
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// {Parent: -1, Func: "f", Pos: <line 2>},
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// {Parent: 0, Func: "g", Pos: <line 5>},
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// {Parent: 1, Func: "h", Pos: <line 8>},
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// {Parent: 1, Func: "h", Pos: <line 9>},
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// }
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//
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// The nodes of h inlined into main will have inlining indexes 2 and 3.
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//
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// Eventually, the compiler extracts a per-function inlining tree from
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// the global inlining tree (see pcln.go).
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type InlTree struct {
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nodes []InlinedCall
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}
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// InlinedCall is a node in an InlTree.
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type InlinedCall struct {
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Parent int // index of the parent in the InlTree or < 0 if outermost call
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Pos src.XPos // position of the inlined call
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Func *LSym // function that was inlined
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ParentPC int32 // PC of instruction just before inlined body. Only valid in local trees.
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}
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// Add adds a new call to the tree, returning its index.
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func (tree *InlTree) Add(parent int, pos src.XPos, func_ *LSym) int {
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r := len(tree.nodes)
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call := InlinedCall{
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Parent: parent,
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Pos: pos,
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Func: func_,
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}
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tree.nodes = append(tree.nodes, call)
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return r
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}
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func (tree *InlTree) Parent(inlIndex int) int {
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return tree.nodes[inlIndex].Parent
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}
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func (tree *InlTree) InlinedFunction(inlIndex int) *LSym {
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return tree.nodes[inlIndex].Func
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}
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func (tree *InlTree) CallPos(inlIndex int) src.XPos {
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return tree.nodes[inlIndex].Pos
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}
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func (tree *InlTree) setParentPC(inlIndex int, pc int32) {
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tree.nodes[inlIndex].ParentPC = pc
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}
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// OutermostPos returns the outermost position corresponding to xpos,
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// which is where xpos was ultimately inlined to. In the example for
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// InlTree, main() contains inlined AST nodes from h(), but the
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// outermost position for those nodes is line 2.
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func (ctxt *Link) OutermostPos(xpos src.XPos) src.Pos {
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pos := ctxt.InnermostPos(xpos)
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outerxpos := xpos
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for ix := pos.Base().InliningIndex(); ix >= 0; {
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call := ctxt.InlTree.nodes[ix]
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ix = call.Parent
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outerxpos = call.Pos
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}
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return ctxt.PosTable.Pos(outerxpos)
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}
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// InnermostPos returns the innermost position corresponding to xpos,
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// that is, the code that is inlined and that inlines nothing else.
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// In the example for InlTree above, the code for println within h
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// would have an innermost position with line number 12, whether
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// h was not inlined, inlined into g, g-then-f, or g-then-f-then-main.
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// This corresponds to what someone debugging main, f, g, or h might
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// expect to see while single-stepping.
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func (ctxt *Link) InnermostPos(xpos src.XPos) src.Pos {
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return ctxt.PosTable.Pos(xpos)
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}
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// AllPos returns a slice of the positions inlined at xpos, from
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// innermost (index zero) to outermost. To avoid gratuitous allocation
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// the result is passed in and extended if necessary.
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func (ctxt *Link) AllPos(xpos src.XPos, result []src.Pos) []src.Pos {
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pos := ctxt.InnermostPos(xpos)
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result = result[:0]
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result = append(result, ctxt.PosTable.Pos(xpos))
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for ix := pos.Base().InliningIndex(); ix >= 0; {
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call := ctxt.InlTree.nodes[ix]
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ix = call.Parent
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result = append(result, ctxt.PosTable.Pos(call.Pos))
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}
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return result
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}
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func dumpInlTree(ctxt *Link, tree InlTree) {
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for i, call := range tree.nodes {
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pos := ctxt.PosTable.Pos(call.Pos)
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ctxt.Logf("%0d | %0d | %s (%s) pc=%d\n", i, call.Parent, call.Func, pos, call.ParentPC)
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}
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}
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