From 8f816259eea991fc354fe44add5223e9ee6b9d67 Mon Sep 17 00:00:00 2001 From: Jeremy Faller Date: Tue, 30 Jul 2019 17:28:29 -0400 Subject: [PATCH] cmd/link: make PCIter available to compiler I'm branching this off cl/187117, and will be reworking that diff stack. Testing: I've run go build -toolexec 'toolstash -cmp' Change-Id: I922a97d0f25d52ea70cd974008a063d4e7af34a7 Reviewed-on: https://go-review.googlesource.com/c/go/+/188023 Reviewed-by: Austin Clements --- src/cmd/internal/obj/pcln.go | 66 ++++++++++++++++++++++++ src/cmd/link/internal/ld/dwarf.go | 68 ++++++++++++------------- src/cmd/link/internal/ld/lib.go | 15 +++--- src/cmd/link/internal/ld/pcln.go | 83 ++++--------------------------- 4 files changed, 117 insertions(+), 115 deletions(-) diff --git a/src/cmd/internal/obj/pcln.go b/src/cmd/internal/obj/pcln.go index e7f340595f..26cbe9fe04 100644 --- a/src/cmd/internal/obj/pcln.go +++ b/src/cmd/internal/obj/pcln.go @@ -384,3 +384,69 @@ func linkpcln(ctxt *Link, cursym *LSym) { } } } + +// PCIter iterates over encoded pcdata tables. +type PCIter struct { + p []byte + PC uint32 + NextPC uint32 + PCScale uint32 + Value int32 + start bool + Done bool +} + +// newPCIter creates a PCIter with a scale factor for the PC step size. +func NewPCIter(pcScale uint32) *PCIter { + it := new(PCIter) + it.PCScale = pcScale + return it +} + +// Next advances it to the Next pc. +func (it *PCIter) Next() { + it.PC = it.NextPC + if it.Done { + return + } + if len(it.p) == 0 { + it.Done = true + return + } + + // Value delta + val, n := binary.Varint(it.p) + if n <= 0 { + log.Fatalf("bad Value varint in pciterNext: read %v", n) + } + it.p = it.p[n:] + + if val == 0 && !it.start { + it.Done = true + return + } + + it.start = false + it.Value += int32(val) + + // pc delta + pc, n := binary.Uvarint(it.p) + if n <= 0 { + log.Fatalf("bad pc varint in pciterNext: read %v", n) + } + it.p = it.p[n:] + + it.NextPC = it.PC + uint32(pc)*it.PCScale +} + +// init prepares it to iterate over p, +// and advances it to the first pc. +func (it *PCIter) Init(p []byte) { + it.p = p + it.PC = 0 + it.NextPC = 0 + it.Value = -1 + it.start = true + it.Done = false + it.Next() +} diff --git a/src/cmd/link/internal/ld/dwarf.go b/src/cmd/link/internal/ld/dwarf.go index 39c8a7f120..7969abb990 100644 --- a/src/cmd/link/internal/ld/dwarf.go +++ b/src/cmd/link/internal/ld/dwarf.go @@ -1212,42 +1212,42 @@ func writelines(ctxt *Link, unit *compilationUnit, ls *sym.Symbol) { file := 1 ls.AddAddr(ctxt.Arch, s) - pcfile := newPCIter(ctxt) - pcline := newPCIter(ctxt) - pcstmt := newPCIter(ctxt) + pcfile := obj.NewPCIter(uint32(ctxt.Arch.MinLC)) + pcline := obj.NewPCIter(uint32(ctxt.Arch.MinLC)) + pcstmt := obj.NewPCIter(uint32(ctxt.Arch.MinLC)) for i, s := range unit.lib.Textp { finddebugruntimepath(s) - pcfile.init(s.FuncInfo.Pcfile.P) - pcline.init(s.FuncInfo.Pcline.P) + pcfile.Init(s.FuncInfo.Pcfile.P) + pcline.Init(s.FuncInfo.Pcline.P) isStmtSym := dwarfFuncSym(ctxt, s, dwarf.IsStmtPrefix, false) if isStmtSym != nil && len(isStmtSym.P) > 0 { - pcstmt.init(isStmtSym.P) + pcstmt.Init(isStmtSym.P) } else { // Assembly files lack a pcstmt section, we assume that every instruction // is a valid statement. - pcstmt.done = true - pcstmt.value = 1 + pcstmt.Done = true + pcstmt.Value = 1 } var thispc uint32 // TODO this loop looks like it could exit with work remaining. - for !pcfile.done && !pcline.done { + for !pcfile.Done && !pcline.Done { // Only changed if it advanced - if int32(file) != pcfile.value { + if int32(file) != pcfile.Value { ls.AddUint8(dwarf.DW_LNS_set_file) - idx, ok := fileNums[int(pcfile.value)] + idx, ok := fileNums[int(pcfile.Value)] if !ok { Exitf("pcln table file missing from DWARF line table") } dwarf.Uleb128put(dwarfctxt, ls, int64(idx)) - file = int(pcfile.value) + file = int(pcfile.Value) } // Only changed if it advanced - if is_stmt != uint8(pcstmt.value) { - new_stmt := uint8(pcstmt.value) + if is_stmt != uint8(pcstmt.Value) { + new_stmt := uint8(pcstmt.Value) switch new_stmt &^ 1 { case obj.PrologueEnd: ls.AddUint8(uint8(dwarf.DW_LNS_set_prologue_end)) @@ -1263,28 +1263,28 @@ func writelines(ctxt *Link, unit *compilationUnit, ls *sym.Symbol) { } // putpcldelta makes a row in the DWARF matrix, always, even if line is unchanged. - putpclcdelta(ctxt, dwarfctxt, ls, uint64(s.Value+int64(thispc)-pc), int64(pcline.value)-int64(line)) + putpclcdelta(ctxt, dwarfctxt, ls, uint64(s.Value+int64(thispc)-pc), int64(pcline.Value)-int64(line)) pc = s.Value + int64(thispc) - line = int(pcline.value) + line = int(pcline.Value) // Take the minimum step forward for the three iterators - thispc = pcfile.nextpc - if pcline.nextpc < thispc { - thispc = pcline.nextpc + thispc = pcfile.NextPC + if pcline.NextPC < thispc { + thispc = pcline.NextPC } - if !pcstmt.done && pcstmt.nextpc < thispc { - thispc = pcstmt.nextpc + if !pcstmt.Done && pcstmt.NextPC < thispc { + thispc = pcstmt.NextPC } - if pcfile.nextpc == thispc { - pcfile.next() + if pcfile.NextPC == thispc { + pcfile.Next() } - if !pcstmt.done && pcstmt.nextpc == thispc { - pcstmt.next() + if !pcstmt.Done && pcstmt.NextPC == thispc { + pcstmt.Next() } - if pcline.nextpc == thispc { - pcline.next() + if pcline.NextPC == thispc { + pcline.Next() } } if is_stmt == 0 && i < len(unit.lib.Textp)-1 { @@ -1451,7 +1451,7 @@ func writeframes(ctxt *Link, syms []*sym.Symbol) []*sym.Symbol { fs.AddBytes(zeros[:pad]) var deltaBuf []byte - pcsp := newPCIter(ctxt) + pcsp := obj.NewPCIter(uint32(ctxt.Arch.MinLC)) for _, s := range ctxt.Textp { if s.FuncInfo == nil { continue @@ -1467,19 +1467,19 @@ func writeframes(ctxt *Link, syms []*sym.Symbol) []*sym.Symbol { deltaBuf = append(deltaBuf, dwarf.DW_CFA_undefined) deltaBuf = dwarf.AppendUleb128(deltaBuf, uint64(thearch.Dwarfreglr)) } - for pcsp.init(s.FuncInfo.Pcsp.P); !pcsp.done; pcsp.next() { - nextpc := pcsp.nextpc + for pcsp.Init(s.FuncInfo.Pcsp.P); !pcsp.Done; pcsp.Next() { + nextpc := pcsp.NextPC // pciterinit goes up to the end of the function, // but DWARF expects us to stop just before the end. if int64(nextpc) == s.Size { nextpc-- - if nextpc < pcsp.pc { + if nextpc < pcsp.PC { continue } } - spdelta := int64(pcsp.value) + spdelta := int64(pcsp.Value) if !haslinkregister(ctxt) { // Return address has been pushed onto stack. spdelta += int64(ctxt.Arch.PtrSize) @@ -1489,7 +1489,7 @@ func writeframes(ctxt *Link, syms []*sym.Symbol) []*sym.Symbol { // TODO(bryanpkc): This is imprecise. In general, the instruction // that stores the return address to the stack frame is not the // same one that allocates the frame. - if pcsp.value > 0 { + if pcsp.Value > 0 { // The return address is preserved at (CFA-frame_size) // after a stack frame has been allocated. deltaBuf = append(deltaBuf, dwarf.DW_CFA_offset_extended_sf) @@ -1503,7 +1503,7 @@ func writeframes(ctxt *Link, syms []*sym.Symbol) []*sym.Symbol { } } - deltaBuf = appendPCDeltaCFA(ctxt.Arch, deltaBuf, int64(nextpc)-int64(pcsp.pc), spdelta) + deltaBuf = appendPCDeltaCFA(ctxt.Arch, deltaBuf, int64(nextpc)-int64(pcsp.PC), spdelta) } pad := int(Rnd(int64(len(deltaBuf)), int64(ctxt.Arch.PtrSize))) - len(deltaBuf) deltaBuf = append(deltaBuf, zeros[:pad]...) diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go index 8919815759..c2de8cbef9 100644 --- a/src/cmd/link/internal/ld/lib.go +++ b/src/cmd/link/internal/ld/lib.go @@ -34,6 +34,7 @@ import ( "bufio" "bytes" "cmd/internal/bio" + "cmd/internal/obj" "cmd/internal/objabi" "cmd/internal/sys" "cmd/link/internal/loadelf" @@ -2137,24 +2138,24 @@ func stkcheck(ctxt *Link, up *chain, depth int) int { endr := len(s.R) var ch1 chain - pcsp := newPCIter(ctxt) + pcsp := obj.NewPCIter(uint32(ctxt.Arch.MinLC)) var r *sym.Reloc - for pcsp.init(s.FuncInfo.Pcsp.P); !pcsp.done; pcsp.next() { + for pcsp.Init(s.FuncInfo.Pcsp.P); !pcsp.Done; pcsp.Next() { // pcsp.value is in effect for [pcsp.pc, pcsp.nextpc). // Check stack size in effect for this span. - if int32(limit)-pcsp.value < 0 { - stkbroke(ctxt, up, int(int32(limit)-pcsp.value)) + if int32(limit)-pcsp.Value < 0 { + stkbroke(ctxt, up, int(int32(limit)-pcsp.Value)) return -1 } // Process calls in this span. - for ; ri < endr && uint32(s.R[ri].Off) < pcsp.nextpc; ri++ { + for ; ri < endr && uint32(s.R[ri].Off) < pcsp.NextPC; ri++ { r = &s.R[ri] switch r.Type { // Direct call. case objabi.R_CALL, objabi.R_CALLARM, objabi.R_CALLARM64, objabi.R_CALLPOWER, objabi.R_CALLMIPS: - ch.limit = int(int32(limit) - pcsp.value - int32(callsize(ctxt))) + ch.limit = int(int32(limit) - pcsp.Value - int32(callsize(ctxt))) ch.sym = r.Sym if stkcheck(ctxt, &ch, depth+1) < 0 { return -1 @@ -2165,7 +2166,7 @@ func stkcheck(ctxt *Link, up *chain, depth int) int { // Arrange the data structures to report both calls, so that // if there is an error, stkprint shows all the steps involved. case objabi.R_CALLIND: - ch.limit = int(int32(limit) - pcsp.value - int32(callsize(ctxt))) + ch.limit = int(int32(limit) - pcsp.Value - int32(callsize(ctxt))) ch.sym = nil ch1.limit = ch.limit - callsize(ctxt) // for morestack in called prologue diff --git a/src/cmd/link/internal/ld/pcln.go b/src/cmd/link/internal/ld/pcln.go index cd8151022a..d9904f9093 100644 --- a/src/cmd/link/internal/ld/pcln.go +++ b/src/cmd/link/internal/ld/pcln.go @@ -5,6 +5,7 @@ package ld import ( + "cmd/internal/obj" "cmd/internal/objabi" "cmd/internal/src" "cmd/internal/sys" @@ -16,72 +17,6 @@ import ( "strings" ) -// PCIter iterates over encoded pcdata tables. -type PCIter struct { - p []byte - pc uint32 - nextpc uint32 - pcscale uint32 - value int32 - start bool - done bool -} - -// newPCIter creates a PCIter and configures it for ctxt's architecture. -func newPCIter(ctxt *Link) *PCIter { - it := new(PCIter) - it.pcscale = uint32(ctxt.Arch.MinLC) - return it -} - -// next advances it to the next pc. -func (it *PCIter) next() { - it.pc = it.nextpc - if it.done { - return - } - if len(it.p) == 0 { - it.done = true - return - } - - // value delta - val, n := binary.Varint(it.p) - if n <= 0 { - log.Fatalf("bad value varint in pciternext: read %v", n) - } - it.p = it.p[n:] - - if val == 0 && !it.start { - it.done = true - return - } - - it.start = false - it.value += int32(val) - - // pc delta - pc, n := binary.Uvarint(it.p) - if n <= 0 { - log.Fatalf("bad pc varint in pciternext: read %v", n) - } - it.p = it.p[n:] - - it.nextpc = it.pc + uint32(pc)*it.pcscale -} - -// init prepares it to iterate over p, -// and advances it to the first pc. -func (it *PCIter) init(p []byte) { - it.p = p - it.pc = 0 - it.nextpc = 0 - it.value = -1 - it.start = true - it.done = false - it.next() -} - func ftabaddstring(ftab *sym.Symbol, s string) int32 { start := len(ftab.P) ftab.Grow(int64(start + len(s) + 1)) // make room for s plus trailing NUL @@ -109,10 +44,10 @@ func renumberfiles(ctxt *Link, files []*sym.Symbol, d *sym.Pcdata) { buf := make([]byte, binary.MaxVarintLen32) newval := int32(-1) var out sym.Pcdata - it := newPCIter(ctxt) - for it.init(d.P); !it.done; it.next() { + it := obj.NewPCIter(uint32(ctxt.Arch.MinLC)) + for it.Init(d.P); !it.Done; it.Next() { // value delta - oldval := it.value + oldval := it.Value var val int32 if oldval == -1 { @@ -132,7 +67,7 @@ func renumberfiles(ctxt *Link, files []*sym.Symbol, d *sym.Pcdata) { out.P = append(out.P, buf[:n]...) // pc delta - pc := (it.nextpc - it.pc) / it.pcscale + pc := (it.NextPC - it.PC) / it.PCScale n = binary.PutUvarint(buf, uint64(pc)) out.P = append(out.P, buf[:n]...) } @@ -337,10 +272,10 @@ func (ctxt *Link) pclntab() { renumberfiles(ctxt, pcln.File, &pcln.Pcfile) if false { // Sanity check the new numbering - it := newPCIter(ctxt) - for it.init(pcln.Pcfile.P); !it.done; it.next() { - if it.value < 1 || it.value > int32(len(ctxt.Filesyms)) { - Errorf(s, "bad file number in pcfile: %d not in range [1, %d]\n", it.value, len(ctxt.Filesyms)) + it := obj.NewPCIter(uint32(ctxt.Arch.MinLC)) + for it.Init(pcln.Pcfile.P); !it.Done; it.Next() { + if it.Value < 1 || it.Value > int32(len(ctxt.Filesyms)) { + Errorf(s, "bad file number in pcfile: %d not in range [1, %d]\n", it.Value, len(ctxt.Filesyms)) errorexit() } }