runtime: framepointers are no longer an experiment - hard code them

I think they are no longer experimental status. Might as well promote
them to permanent.

Change-Id: Id1259601b3dd2061dd60df86ee48080bfb575d2f
Reviewed-on: https://go-review.googlesource.com/c/go/+/249857
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

diff --git a/src/cmd/compile/internal/gc/pgen.go b/src/cmd/compile/internal/gc/pgen.go
index ca8cccf4ae1a32aed1e666d339d765fb50bb30b9..74262595b05d93ac9f082543e1445c402b56a9d8 100644 (file)
--- a/src/cmd/compile/internal/gc/pgen.go
+++ b/src/cmd/compile/internal/gc/pgen.go
@@ -507,7 +507,7 @@ func createSimpleVar(fnsym *obj.LSym, n *Node) *dwarf.Var {
                if Ctxt.FixedFrameSize() == 0 {
                        offs -= int64(Widthptr)
                }
-               if objabi.Framepointer_enabled(objabi.GOOS, objabi.GOARCH) || objabi.GOARCH == "arm64" {
+               if objabi.Framepointer_enabled || objabi.GOARCH == "arm64" {
                        // There is a word space for FP on ARM64 even if the frame pointer is disabled
                        offs -= int64(Widthptr)
                }
@@ -703,7 +703,7 @@ func stackOffset(slot ssa.LocalSlot) int32 {
                if Ctxt.FixedFrameSize() == 0 {
                        base -= int64(Widthptr)
                }
-               if objabi.Framepointer_enabled(objabi.GOOS, objabi.GOARCH) || objabi.GOARCH == "arm64" {
+               if objabi.Framepointer_enabled || objabi.GOARCH == "arm64" {
                        // There is a word space for FP on ARM64 even if the frame pointer is disabled
                        base -= int64(Widthptr)
                }

diff --git a/src/cmd/compile/internal/ssa/regalloc.go b/src/cmd/compile/internal/ssa/regalloc.go
index a2be7bb596279e191abdd01ba647d317697e3683..64c6aed3e72dcec73e0945c209ce3eec76f75761 100644 (file)
--- a/src/cmd/compile/internal/ssa/regalloc.go
+++ b/src/cmd/compile/internal/ssa/regalloc.go
@@ -588,7 +588,7 @@ func (s *regAllocState) init(f *Func) {
        if s.f.Config.hasGReg {
                s.allocatable &^= 1 << s.GReg
        }
-       if s.f.Config.ctxt.Framepointer_enabled && s.f.Config.FPReg >= 0 {
+       if objabi.Framepointer_enabled && s.f.Config.FPReg >= 0 {
                s.allocatable &^= 1 << uint(s.f.Config.FPReg)
        }
        if s.f.Config.LinkReg != -1 {

diff --git a/src/cmd/internal/obj/arm64/obj7.go b/src/cmd/internal/obj/arm64/obj7.go
index 0d74430053377e45097a6ee4e46b619b616f373b..f54429fabed1753a8f0c739ec97b20dc8a64da05 100644 (file)
--- a/src/cmd/internal/obj/arm64/obj7.go
+++ b/src/cmd/internal/obj/arm64/obj7.go
@@ -621,7 +621,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 
                        prologueEnd.Pos = prologueEnd.Pos.WithXlogue(src.PosPrologueEnd)
 
-                       if objabi.Framepointer_enabled(objabi.GOOS, objabi.GOARCH) {
+                       if objabi.Framepointer_enabled {
                                q1 = obj.Appendp(q1, c.newprog)
                                q1.Pos = p.Pos
                                q1.As = AMOVD
@@ -764,7 +764,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
                                        p.To.Reg = REGSP
                                        p.Spadj = -c.autosize
 
-                                       if objabi.Framepointer_enabled(objabi.GOOS, objabi.GOARCH) {
+                                       if objabi.Framepointer_enabled {
                                                p = obj.Appendp(p, c.newprog)
                                                p.As = ASUB
                                                p.From.Type = obj.TYPE_CONST
@@ -777,7 +777,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
                        } else {
                                /* want write-back pre-indexed SP+autosize -> SP, loading REGLINK*/
 
-                               if objabi.Framepointer_enabled(objabi.GOOS, objabi.GOARCH) {
+                               if objabi.Framepointer_enabled {
                                        p.As = AMOVD
                                        p.From.Type = obj.TYPE_MEM
                                        p.From.Reg = REGSP
@@ -865,7 +865,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
                        }
 
                case obj.ADUFFCOPY:
-                       if objabi.Framepointer_enabled(objabi.GOOS, objabi.GOARCH) {
+                       if objabi.Framepointer_enabled {
                                //  ADR ret_addr, R27
                                //  STP (FP, R27), -24(SP)
                                //  SUB 24, SP, FP
@@ -918,7 +918,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
                        }
 
                case obj.ADUFFZERO:
-                       if objabi.Framepointer_enabled(objabi.GOOS, objabi.GOARCH) {
+                       if objabi.Framepointer_enabled {
                                //  ADR ret_addr, R27
                                //  STP (FP, R27), -24(SP)
                                //  SUB 24, SP, FP

diff --git a/src/cmd/internal/obj/link.go b/src/cmd/internal/obj/link.go
index 311e5ae2e8ab9a06b71dbdcaaa865402b2a0ab66..1fc90db86451533723f018e04936a5518227f7f5 100644 (file)
--- a/src/cmd/internal/obj/link.go
+++ b/src/cmd/internal/obj/link.go
@@ -682,10 +682,9 @@ type Link struct {
        GenAbstractFunc    func(fn *LSym)
        Errors             int
 
-       InParallel           bool // parallel backend phase in effect
-       Framepointer_enabled bool
-       UseBASEntries        bool // use Base Address Selection Entries in location lists and PC ranges
-       IsAsm                bool // is the source assembly language, which may contain surprising idioms (e.g., call tables)
+       InParallel    bool // parallel backend phase in effect
+       UseBASEntries bool // use Base Address Selection Entries in location lists and PC ranges
+       IsAsm         bool // is the source assembly language, which may contain surprising idioms (e.g., call tables)
 
        // state for writing objects
        Text []*LSym

diff --git a/src/cmd/internal/obj/sym.go b/src/cmd/internal/obj/sym.go
index 34f61b7f62e48a7321ced33a0ce6278d0b3129c3..d58877ee152f595e9d5c345b8d1b75bff87bef4e 100644 (file)
--- a/src/cmd/internal/obj/sym.go
+++ b/src/cmd/internal/obj/sym.go
@@ -53,7 +53,6 @@ func Linknew(arch *LinkArch) *Link {
        }
 
        ctxt.Flag_optimize = true
-       ctxt.Framepointer_enabled = objabi.Framepointer_enabled(objabi.GOOS, arch.Name)
        return ctxt
 }
 

diff --git a/src/cmd/internal/obj/x86/asm6.go b/src/cmd/internal/obj/x86/asm6.go
index 82a2e6adc4c43553783948e4b02aded38bb1f59a..a53063637385287222fe5c55acc9ffb592babab1 100644 (file)
--- a/src/cmd/internal/obj/x86/asm6.go
+++ b/src/cmd/internal/obj/x86/asm6.go
@@ -4833,12 +4833,12 @@ func (ab *AsmBuf) doasm(ctxt *obj.Link, cursym *obj.LSym, p *obj.Prog) {
                                        ctxt.Diag("directly calling duff when dynamically linking Go")
                                }
 
-                               if ctxt.Framepointer_enabled && yt.zcase == Zcallduff && ctxt.Arch.Family == sys.AMD64 {
+                               if yt.zcase == Zcallduff && ctxt.Arch.Family == sys.AMD64 {
                                        // Maintain BP around call, since duffcopy/duffzero can't do it
                                        // (the call jumps into the middle of the function).
                                        // This makes it possible to see call sites for duffcopy/duffzero in
                                        // BP-based profiling tools like Linux perf (which is the
-                                       // whole point of obj.Framepointer_enabled).
+                                       // whole point of maintaining frame pointers in Go).
                                        // MOVQ BP, -16(SP)
                                        // LEAQ -16(SP), BP
                                        ab.Put(bpduff1)
@@ -4852,7 +4852,7 @@ func (ab *AsmBuf) doasm(ctxt *obj.Link, cursym *obj.LSym, p *obj.Prog) {
                                r.Siz = 4
                                ab.PutInt32(0)
 
-                               if ctxt.Framepointer_enabled && yt.zcase == Zcallduff && ctxt.Arch.Family == sys.AMD64 {
+                               if yt.zcase == Zcallduff && ctxt.Arch.Family == sys.AMD64 {
                                        // Pop BP pushed above.
                                        // MOVQ 0(BP), BP
                                        ab.Put(bpduff2)

diff --git a/src/cmd/internal/obj/x86/obj6.go b/src/cmd/internal/obj/x86/obj6.go
index c1e5bea055289209120499a06350356cc98ab9f7..016c247ff553a93ace09d40e919f9bb85478ff38 100644 (file)
--- a/src/cmd/internal/obj/x86/obj6.go
+++ b/src/cmd/internal/obj/x86/obj6.go
@@ -582,7 +582,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
        }
 
        var bpsize int
-       if ctxt.Arch.Family == sys.AMD64 && ctxt.Framepointer_enabled &&
+       if ctxt.Arch.Family == sys.AMD64 &&
                !p.From.Sym.NoFrame() && // (1) below
                !(autoffset == 0 && p.From.Sym.NoSplit()) && // (2) below
                !(autoffset == 0 && !hasCall) { // (3) below

diff --git a/src/cmd/internal/objabi/util.go b/src/cmd/internal/objabi/util.go
index f7873a42b9d6d03b1f7f4f3b3000ae38d079b05a..6c5a9ba4410fd7afa04993149d25a614d977127e 100644 (file)
--- a/src/cmd/internal/objabi/util.go
+++ b/src/cmd/internal/objabi/util.go
@@ -133,9 +133,8 @@ func init() {
        }
 }
 
-func Framepointer_enabled(goos, goarch string) bool {
-       return framepointer_enabled != 0 && (goarch == "amd64" || goarch == "arm64" && (goos == "linux" || goos == "darwin"))
-}
+// Note: must agree with runtime.framepointer_enabled.
+var Framepointer_enabled = GOARCH == "amd64" || GOARCH == "arm64" && (GOOS == "linux" || GOOS == "darwin")
 
 func addexp(s string) {
        // Could do general integer parsing here, but the runtime copy doesn't yet.
@@ -159,7 +158,6 @@ func addexp(s string) {
 }
 
 var (
-       framepointer_enabled      int = 1
        Fieldtrack_enabled        int
        Preemptibleloops_enabled  int
        Staticlockranking_enabled int
@@ -174,7 +172,6 @@ var exper = []struct {
        val  *int
 }{
        {"fieldtrack", &Fieldtrack_enabled},
-       {"framepointer", &framepointer_enabled},
        {"preemptibleloops", &Preemptibleloops_enabled},
        {"staticlockranking", &Staticlockranking_enabled},
 }

diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
index 09c7bbfb53d725033c91673cad90c5ea54260fb2..d6ee437bcac3f36d07c15d03d423002aadde99d3 100644 (file)
--- a/src/cmd/link/internal/ld/lib.go
+++ b/src/cmd/link/internal/ld/lib.go
@@ -775,14 +775,6 @@ func (ctxt *Link) linksetup() {
                        sb.SetSize(0)
                        sb.AddUint8(uint8(objabi.GOARM))
                }
-
-               if objabi.Framepointer_enabled(objabi.GOOS, objabi.GOARCH) {
-                       fpe := ctxt.loader.LookupOrCreateSym("runtime.framepointer_enabled", 0)
-                       sb := ctxt.loader.MakeSymbolUpdater(fpe)
-                       sb.SetType(sym.SNOPTRDATA)
-                       sb.SetSize(0)
-                       sb.AddUint8(1)
-               }
        } else {
                // If OTOH the module does not contain the runtime package,
                // create a local symbol for the moduledata.

diff --git a/src/runtime/cgocall.go b/src/runtime/cgocall.go
index 099aa540e0fd250dfb7ecfa50091ab48787911ce..427ed0ffb9f71336db0809a222af3c8594d4e2e0 100644 (file)
--- a/src/runtime/cgocall.go
+++ b/src/runtime/cgocall.go
@@ -286,13 +286,8 @@ func cgocallbackg1(ctxt uintptr) {
                // Additional two words (16-byte alignment) are for saving FP.
                cb = (*args)(unsafe.Pointer(sp + 7*sys.PtrSize))
        case "amd64":
-               // On amd64, stack frame is two words, plus caller PC.
-               if framepointer_enabled {
-                       // In this case, there's also saved BP.
-                       cb = (*args)(unsafe.Pointer(sp + 4*sys.PtrSize))
-                       break
-               }
-               cb = (*args)(unsafe.Pointer(sp + 3*sys.PtrSize))
+               // On amd64, stack frame is two words, plus caller PC and BP.
+               cb = (*args)(unsafe.Pointer(sp + 4*sys.PtrSize))
        case "386":
                // On 386, stack frame is three words, plus caller PC.
                cb = (*args)(unsafe.Pointer(sp + 4*sys.PtrSize))

diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index 5e38b3194c8c5180c4658b577b9fa679abf12b72..341d52aea8e1b01258b706ee07b03215532065fa 100644 (file)
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -5459,9 +5459,6 @@ func setMaxThreads(in int) (out int) {
 }
 
 func haveexperiment(name string) bool {
-       if name == "framepointer" {
-               return framepointer_enabled // set by linker
-       }
        x := sys.Goexperiment
        for x != "" {
                xname := ""

diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go
index 64c6cc7198300239156cb07eb32e5de6180d2427..a3157037e7925233d38da03e693ab36f2598d321 100644 (file)
--- a/src/runtime/runtime2.go
+++ b/src/runtime/runtime2.go
@@ -329,7 +329,7 @@ type gobuf struct {
        ctxt unsafe.Pointer
        ret  sys.Uintreg
        lr   uintptr
-       bp   uintptr // for GOEXPERIMENT=framepointer
+       bp   uintptr // for framepointer-enabled architectures
 }
 
 // sudog represents a g in a wait list, such as for sending/receiving
@@ -1046,8 +1046,7 @@ var (
        isIntel              bool
        lfenceBeforeRdtsc    bool
 
-       goarm                uint8 // set by cmd/link on arm systems
-       framepointer_enabled bool  // set by cmd/link
+       goarm uint8 // set by cmd/link on arm systems
 )
 
 // Set by the linker so the runtime can determine the buildmode.
@@ -1055,3 +1054,6 @@ var (
        islibrary bool // -buildmode=c-shared
        isarchive bool // -buildmode=c-archive
 )
+
+// Must agree with cmd/internal/objabi.Framepointer_enabled.
+const framepointer_enabled = GOARCH == "amd64" || GOARCH == "arm64" && (GOOS == "linux" || GOOS == "darwin")

diff --git a/src/runtime/stack.go b/src/runtime/stack.go
index 0e930f60db4cc32e54c7a9ac7de1adc90125f998..403b3c313ef26bd7c77406a211a296bbaaf16657 100644 (file)
--- a/src/runtime/stack.go
+++ b/src/runtime/stack.go
@@ -648,12 +648,8 @@ func adjustframe(frame *stkframe, arg unsafe.Pointer) bool {
        }
 
        // Adjust saved base pointer if there is one.
+       // TODO what about arm64 frame pointer adjustment?
        if sys.ArchFamily == sys.AMD64 && frame.argp-frame.varp == 2*sys.RegSize {
-               if !framepointer_enabled {
-                       print("runtime: found space for saved base pointer, but no framepointer experiment\n")
-                       print("argp=", hex(frame.argp), " varp=", hex(frame.varp), "\n")
-                       throw("bad frame layout")
-               }
                if stackDebug >= 3 {
                        print("      saved bp\n")
                }

diff --git a/src/runtime/traceback.go b/src/runtime/traceback.go
index 7850eceafa036914ec247e87315231a69c279e36..94f4a44976b673a2c325700e11653986760cbe5e 100644 (file)
--- a/src/runtime/traceback.go
+++ b/src/runtime/traceback.go
@@ -269,9 +269,9 @@ func gentraceback(pc0, sp0, lr0 uintptr, gp *g, skip int, pcbuf *uintptr, max in
                        frame.varp -= sys.RegSize
                }
 
-               // If framepointer_enabled and there's a frame, then
-               // there's a saved bp here.
-               if frame.varp > frame.sp && (framepointer_enabled && GOARCH == "amd64" || GOARCH == "arm64") {
+               // For architectures with frame pointers, if there's
+               // a frame, then there's a saved frame pointer here.
+               if frame.varp > frame.sp && (GOARCH == "amd64" || GOARCH == "arm64") {
                        frame.varp -= sys.RegSize
                }