1 files changed, 454 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/dwarfgen/dwinl.go b/src/cmd/compile/internal/dwarfgen/dwinl.go
new file mode 100644
index 0000000..c785e06
--- /dev/null
+++ b/src/cmd/compile/internal/dwarfgen/dwinl.go
@@ -0,0 +1,454 @@
+// Copyright 2017 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 dwarfgen
+
+import (
+	"fmt"
+	"strings"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/internal/dwarf"
+	"cmd/internal/obj"
+	"cmd/internal/src"
+)
+
+// To identify variables by original source position.
+type varPos struct {
+	DeclName string
+	DeclFile string
+	DeclLine uint
+	DeclCol  uint
+}
+
+// This is the main entry point for collection of raw material to
+// drive generation of DWARF "inlined subroutine" DIEs. See proposal
+// 22080 for more details and background info.
+func assembleInlines(fnsym *obj.LSym, dwVars []*dwarf.Var) dwarf.InlCalls {
+	var inlcalls dwarf.InlCalls
+
+	if base.Debug.DwarfInl != 0 {
+		base.Ctxt.Logf("assembling DWARF inlined routine info for %v\n", fnsym.Name)
+	}
+
+	// This maps inline index (from Ctxt.InlTree) to index in inlcalls.Calls
+	imap := make(map[int]int)
+
+	// Walk progs to build up the InlCalls data structure
+	var prevpos src.XPos
+	for p := fnsym.Func().Text; p != nil; p = p.Link {
+		if p.Pos == prevpos {
+			continue
+		}
+		ii := posInlIndex(p.Pos)
+		if ii >= 0 {
+			insertInlCall(&inlcalls, ii, imap)
+		}
+		prevpos = p.Pos
+	}
+
+	// This is used to partition DWARF vars by inline index. Vars not
+	// produced by the inliner will wind up in the vmap[0] entry.
+	vmap := make(map[int32][]*dwarf.Var)
+
+	// Now walk the dwarf vars and partition them based on whether they
+	// were produced by the inliner (dwv.InlIndex > 0) or were original
+	// vars/params from the function (dwv.InlIndex == 0).
+	for _, dwv := range dwVars {
+
+		vmap[dwv.InlIndex] = append(vmap[dwv.InlIndex], dwv)
+
+		// Zero index => var was not produced by an inline
+		if dwv.InlIndex == 0 {
+			continue
+		}
+
+		// Look up index in our map, then tack the var in question
+		// onto the vars list for the correct inlined call.
+		ii := int(dwv.InlIndex) - 1
+		idx, ok := imap[ii]
+		if !ok {
+			// We can occasionally encounter a var produced by the
+			// inliner for which there is no remaining prog; add a new
+			// entry to the call list in this scenario.
+			idx = insertInlCall(&inlcalls, ii, imap)
+		}
+		inlcalls.Calls[idx].InlVars =
+			append(inlcalls.Calls[idx].InlVars, dwv)
+	}
+
+	// Post process the map above to assign child indices to vars.
+	//
+	// A given variable is treated differently depending on whether it
+	// is part of the top-level function (ii == 0) or if it was
+	// produced as a result of an inline (ii != 0).
+	//
+	// If a variable was not produced by an inline and its containing
+	// function was not inlined, then we just assign an ordering of
+	// based on variable name.
+	//
+	// If a variable was not produced by an inline and its containing
+	// function was inlined, then we need to assign a child index
+	// based on the order of vars in the abstract function (in
+	// addition, those vars that don't appear in the abstract
+	// function, such as "~r1", are flagged as such).
+	//
+	// If a variable was produced by an inline, then we locate it in
+	// the pre-inlining decls for the target function and assign child
+	// index accordingly.
+	for ii, sl := range vmap {
+		var m map[varPos]int
+		if ii == 0 {
+			if !fnsym.WasInlined() {
+				for j, v := range sl {
+					v.ChildIndex = int32(j)
+				}
+				continue
+			}
+			m = makePreinlineDclMap(fnsym)
+		} else {
+			ifnlsym := base.Ctxt.InlTree.InlinedFunction(int(ii - 1))
+			m = makePreinlineDclMap(ifnlsym)
+		}
+
+		// Here we assign child indices to variables based on
+		// pre-inlined decls, and set the "IsInAbstract" flag
+		// appropriately. In addition: parameter and local variable
+		// names are given "middle dot" version numbers as part of the
+		// writing them out to export data (see issue 4326). If DWARF
+		// inlined routine generation is turned on, we want to undo
+		// this versioning, since DWARF variables in question will be
+		// parented by the inlined routine and not the top-level
+		// caller.
+		synthCount := len(m)
+		for _, v := range sl {
+			canonName := unversion(v.Name)
+			vp := varPos{
+				DeclName: canonName,
+				DeclFile: v.DeclFile,
+				DeclLine: v.DeclLine,
+				DeclCol:  v.DeclCol,
+			}
+			synthesized := strings.HasPrefix(v.Name, "~r") || canonName == "_" || strings.HasPrefix(v.Name, "~b")
+			if idx, found := m[vp]; found {
+				v.ChildIndex = int32(idx)
+				v.IsInAbstract = !synthesized
+				v.Name = canonName
+			} else {
+				// Variable can't be found in the pre-inline dcl list.
+				// In the top-level case (ii=0) this can happen
+				// because a composite variable was split into pieces,
+				// and we're looking at a piece. We can also see
+				// return temps (~r%d) that were created during
+				// lowering, or unnamed params ("_").
+				v.ChildIndex = int32(synthCount)
+				synthCount++
+			}
+		}
+	}
+
+	// Make a second pass through the progs to compute PC ranges for
+	// the various inlined calls.
+	start := int64(-1)
+	curii := -1
+	var prevp *obj.Prog
+	for p := fnsym.Func().Text; p != nil; prevp, p = p, p.Link {
+		if prevp != nil && p.Pos == prevp.Pos {
+			continue
+		}
+		ii := posInlIndex(p.Pos)
+		if ii == curii {
+			continue
+		}
+		// Close out the current range
+		if start != -1 {
+			addRange(inlcalls.Calls, start, p.Pc, curii, imap)
+		}
+		// Begin new range
+		start = p.Pc
+		curii = ii
+	}
+	if start != -1 {
+		addRange(inlcalls.Calls, start, fnsym.Size, curii, imap)
+	}
+
+	// Issue 33188: if II foo is a child of II bar, then ensure that
+	// bar's ranges include the ranges of foo (the loop above will produce
+	// disjoint ranges).
+	for k, c := range inlcalls.Calls {
+		if c.Root {
+			unifyCallRanges(inlcalls, k)
+		}
+	}
+
+	// Debugging
+	if base.Debug.DwarfInl != 0 {
+		dumpInlCalls(inlcalls)
+		dumpInlVars(dwVars)
+	}
+
+	// Perform a consistency check on inlined routine PC ranges
+	// produced by unifyCallRanges above. In particular, complain in
+	// cases where you have A -> B -> C (e.g. C is inlined into B, and
+	// B is inlined into A) and the ranges for B are not enclosed
+	// within the ranges for A, or C within B.
+	for k, c := range inlcalls.Calls {
+		if c.Root {
+			checkInlCall(fnsym.Name, inlcalls, fnsym.Size, k, -1)
+		}
+	}
+
+	return inlcalls
+}
+
+// Secondary hook for DWARF inlined subroutine generation. This is called
+// late in the compilation when it is determined that we need an
+// abstract function DIE for an inlined routine imported from a
+// previously compiled package.
+func AbstractFunc(fn *obj.LSym) {
+	ifn := base.Ctxt.DwFixups.GetPrecursorFunc(fn)
+	if ifn == nil {
+		base.Ctxt.Diag("failed to locate precursor fn for %v", fn)
+		return
+	}
+	_ = ifn.(*ir.Func)
+	if base.Debug.DwarfInl != 0 {
+		base.Ctxt.Logf("DwarfAbstractFunc(%v)\n", fn.Name)
+	}
+	base.Ctxt.DwarfAbstractFunc(ifn, fn, base.Ctxt.Pkgpath)
+}
+
+// Undo any versioning performed when a name was written
+// out as part of export data.
+func unversion(name string) string {
+	if i := strings.Index(name, "·"); i > 0 {
+		name = name[:i]
+	}
+	return name
+}
+
+// Given a function that was inlined as part of the compilation, dig
+// up the pre-inlining DCL list for the function and create a map that
+// supports lookup of pre-inline dcl index, based on variable
+// position/name. NB: the recipe for computing variable pos/file/line
+// needs to be kept in sync with the similar code in gc.createSimpleVars
+// and related functions.
+func makePreinlineDclMap(fnsym *obj.LSym) map[varPos]int {
+	dcl := preInliningDcls(fnsym)
+	m := make(map[varPos]int)
+	for i, n := range dcl {
+		pos := base.Ctxt.InnermostPos(n.Pos())
+		vp := varPos{
+			DeclName: unversion(n.Sym().Name),
+			DeclFile: pos.RelFilename(),
+			DeclLine: pos.RelLine(),
+			DeclCol:  pos.RelCol(),
+		}
+		if _, found := m[vp]; found {
+			// We can see collisions (variables with the same name/file/line/col) in obfuscated or machine-generated code -- see issue 44378 for an example. Skip duplicates in such cases, since it is unlikely that a human will be debugging such code.
+			continue
+		}
+		m[vp] = i
+	}
+	return m
+}
+
+func insertInlCall(dwcalls *dwarf.InlCalls, inlIdx int, imap map[int]int) int {
+	callIdx, found := imap[inlIdx]
+	if found {
+		return callIdx
+	}
+
+	// Haven't seen this inline yet. Visit parent of inline if there
+	// is one. We do this first so that parents appear before their
+	// children in the resulting table.
+	parCallIdx := -1
+	parInlIdx := base.Ctxt.InlTree.Parent(inlIdx)
+	if parInlIdx >= 0 {
+		parCallIdx = insertInlCall(dwcalls, parInlIdx, imap)
+	}
+
+	// Create new entry for this inline
+	inlinedFn := base.Ctxt.InlTree.InlinedFunction(inlIdx)
+	callXPos := base.Ctxt.InlTree.CallPos(inlIdx)
+	absFnSym := base.Ctxt.DwFixups.AbsFuncDwarfSym(inlinedFn)
+	pb := base.Ctxt.PosTable.Pos(callXPos).Base()
+	callFileSym := base.Ctxt.Lookup(pb.SymFilename())
+	ic := dwarf.InlCall{
+		InlIndex:  inlIdx,
+		CallFile:  callFileSym,
+		CallLine:  uint32(callXPos.Line()),
+		AbsFunSym: absFnSym,
+		Root:      parCallIdx == -1,
+	}
+	dwcalls.Calls = append(dwcalls.Calls, ic)
+	callIdx = len(dwcalls.Calls) - 1
+	imap[inlIdx] = callIdx
+
+	if parCallIdx != -1 {
+		// Add this inline to parent's child list
+		dwcalls.Calls[parCallIdx].Children = append(dwcalls.Calls[parCallIdx].Children, callIdx)
+	}
+
+	return callIdx
+}
+
+// Given a src.XPos, return its associated inlining index if it
+// corresponds to something created as a result of an inline, or -1 if
+// there is no inline info. Note that the index returned will refer to
+// the deepest call in the inlined stack, e.g. if you have "A calls B
+// calls C calls D" and all three callees are inlined (B, C, and D),
+// the index for a node from the inlined body of D will refer to the
+// call to D from C. Whew.
+func posInlIndex(xpos src.XPos) int {
+	pos := base.Ctxt.PosTable.Pos(xpos)
+	if b := pos.Base(); b != nil {
+		ii := b.InliningIndex()
+		if ii >= 0 {
+			return ii
+		}
+	}
+	return -1
+}
+
+func addRange(calls []dwarf.InlCall, start, end int64, ii int, imap map[int]int) {
+	if start == -1 {
+		panic("bad range start")
+	}
+	if end == -1 {
+		panic("bad range end")
+	}
+	if ii == -1 {
+		return
+	}
+	if start == end {
+		return
+	}
+	// Append range to correct inlined call
+	callIdx, found := imap[ii]
+	if !found {
+		base.Fatalf("can't find inlIndex %d in imap for prog at %d\n", ii, start)
+	}
+	call := &calls[callIdx]
+	call.Ranges = append(call.Ranges, dwarf.Range{Start: start, End: end})
+}
+
+func dumpInlCall(inlcalls dwarf.InlCalls, idx, ilevel int) {
+	for i := 0; i < ilevel; i++ {
+		base.Ctxt.Logf("  ")
+	}
+	ic := inlcalls.Calls[idx]
+	callee := base.Ctxt.InlTree.InlinedFunction(ic.InlIndex)
+	base.Ctxt.Logf("  %d: II:%d (%s) V: (", idx, ic.InlIndex, callee.Name)
+	for _, f := range ic.InlVars {
+		base.Ctxt.Logf(" %v", f.Name)
+	}
+	base.Ctxt.Logf(" ) C: (")
+	for _, k := range ic.Children {
+		base.Ctxt.Logf(" %v", k)
+	}
+	base.Ctxt.Logf(" ) R:")
+	for _, r := range ic.Ranges {
+		base.Ctxt.Logf(" [%d,%d)", r.Start, r.End)
+	}
+	base.Ctxt.Logf("\n")
+	for _, k := range ic.Children {
+		dumpInlCall(inlcalls, k, ilevel+1)
+	}
+
+}
+
+func dumpInlCalls(inlcalls dwarf.InlCalls) {
+	for k, c := range inlcalls.Calls {
+		if c.Root {
+			dumpInlCall(inlcalls, k, 0)
+		}
+	}
+}
+
+func dumpInlVars(dwvars []*dwarf.Var) {
+	for i, dwv := range dwvars {
+		typ := "local"
+		if dwv.Abbrev == dwarf.DW_ABRV_PARAM_LOCLIST || dwv.Abbrev == dwarf.DW_ABRV_PARAM {
+			typ = "param"
+		}
+		ia := 0
+		if dwv.IsInAbstract {
+			ia = 1
+		}
+		base.Ctxt.Logf("V%d: %s CI:%d II:%d IA:%d %s\n", i, dwv.Name, dwv.ChildIndex, dwv.InlIndex-1, ia, typ)
+	}
+}
+
+func rangesContains(par []dwarf.Range, rng dwarf.Range) (bool, string) {
+	for _, r := range par {
+		if rng.Start >= r.Start && rng.End <= r.End {
+			return true, ""
+		}
+	}
+	msg := fmt.Sprintf("range [%d,%d) not contained in {", rng.Start, rng.End)
+	for _, r := range par {
+		msg += fmt.Sprintf(" [%d,%d)", r.Start, r.End)
+	}
+	msg += " }"
+	return false, msg
+}
+
+func rangesContainsAll(parent, child []dwarf.Range) (bool, string) {
+	for _, r := range child {
+		c, m := rangesContains(parent, r)
+		if !c {
+			return false, m
+		}
+	}
+	return true, ""
+}
+
+// checkInlCall verifies that the PC ranges for inline info 'idx' are
+// enclosed/contained within the ranges of its parent inline (or if
+// this is a root/toplevel inline, checks that the ranges fall within
+// the extent of the top level function). A panic is issued if a
+// malformed range is found.
+func checkInlCall(funcName string, inlCalls dwarf.InlCalls, funcSize int64, idx, parentIdx int) {
+
+	// Callee
+	ic := inlCalls.Calls[idx]
+	callee := base.Ctxt.InlTree.InlinedFunction(ic.InlIndex).Name
+	calleeRanges := ic.Ranges
+
+	// Caller
+	caller := funcName
+	parentRanges := []dwarf.Range{dwarf.Range{Start: int64(0), End: funcSize}}
+	if parentIdx != -1 {
+		pic := inlCalls.Calls[parentIdx]
+		caller = base.Ctxt.InlTree.InlinedFunction(pic.InlIndex).Name
+		parentRanges = pic.Ranges
+	}
+
+	// Callee ranges contained in caller ranges?
+	c, m := rangesContainsAll(parentRanges, calleeRanges)
+	if !c {
+		base.Fatalf("** malformed inlined routine range in %s: caller %s callee %s II=%d %s\n", funcName, caller, callee, idx, m)
+	}
+
+	// Now visit kids
+	for _, k := range ic.Children {
+		checkInlCall(funcName, inlCalls, funcSize, k, idx)
+	}
+}
+
+// unifyCallRanges ensures that the ranges for a given inline
+// transitively include all of the ranges for its child inlines.
+func unifyCallRanges(inlcalls dwarf.InlCalls, idx int) {
+	ic := &inlcalls.Calls[idx]
+	for _, childIdx := range ic.Children {
+		// First make sure child ranges are unified.
+		unifyCallRanges(inlcalls, childIdx)
+
+		// Then merge child ranges into ranges for this inline.
+		cic := inlcalls.Calls[childIdx]
+		ic.Ranges = dwarf.MergeRanges(ic.Ranges, cic.Ranges)
+	}
+}