From 3100dc1a7fe3f3302cf2419298b0585bc8e83890 Mon Sep 17 00:00:00 2001 From: Josh Bleecher Snyder Date: Mon, 27 Sep 2021 14:27:20 -0700 Subject: cmd/link,runtime: remove relocations from stkobjs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Use an offset from go.func.* instead. This removes the last relocation from funcdata symbols, which lets us simplify that code. size before after Δ % addr2line 3683218 3680706 -2512 -0.068% api 4951074 4944850 -6224 -0.126% asm 4744258 4757586 +13328 +0.281% buildid 2419986 2418546 -1440 -0.060% cgo 4218306 4197346 -20960 -0.497% compile 22132066 22076882 -55184 -0.249% cover 4432834 4411362 -21472 -0.484% dist 3111202 3091346 -19856 -0.638% doc 3583602 3563234 -20368 -0.568% fix 3023922 3020658 -3264 -0.108% link 6188034 6164642 -23392 -0.378% nm 3665826 3646818 -19008 -0.519% objdump 4015234 4012450 -2784 -0.069% pack 2155010 2153554 -1456 -0.068% pprof 13044178 13011522 -32656 -0.250% test2json 2402146 2383906 -18240 -0.759% trace 9765410 9736514 -28896 -0.296% vet 6681250 6655058 -26192 -0.392% total 104217556 103926980 -290576 -0.279% relocs before after Δ % addr2line 25563 25066 -497 -1.944% api 18409 17176 -1233 -6.698% asm 18903 18271 -632 -3.343% buildid 9513 9233 -280 -2.943% cgo 17103 16222 -881 -5.151% compile 64825 60421 -4404 -6.794% cover 19464 18479 -985 -5.061% dist 10798 10135 -663 -6.140% doc 13503 12735 -768 -5.688% fix 11465 10820 -645 -5.626% link 23214 21849 -1365 -5.880% nm 25480 24987 -493 -1.935% objdump 26610 26057 -553 -2.078% pack 7951 7665 -286 -3.597% pprof 63964 60761 -3203 -5.008% test2json 8735 8389 -346 -3.961% trace 39639 37180 -2459 -6.203% vet 25970 24044 -1926 -7.416% total 431108 409489 -21619 -5.015% Change-Id: I43c26196a008da6d1cb3a782eea2f428778bd569 Reviewed-on: https://go-review.googlesource.com/c/go/+/353138 Trust: Josh Bleecher Snyder Run-TryBot: Josh Bleecher Snyder TryBot-Result: Go Bot Reviewed-by: Cherry Mui --- src/runtime/stack.go | 68 ++++++++++++++++++++++++++++++++++++---------------- 1 file changed, 48 insertions(+), 20 deletions(-) (limited to 'src/runtime/stack.go') diff --git a/src/runtime/stack.go b/src/runtime/stack.go index 0946e6975a..efaa799022 100644 --- a/src/runtime/stack.go +++ b/src/runtime/stack.go @@ -691,7 +691,8 @@ func adjustframe(frame *stkframe, arg unsafe.Pointer) bool { // Adjust pointers in all stack objects (whether they are live or not). // See comments in mgcmark.go:scanframeworker. if frame.varp != 0 { - for _, obj := range objs { + for i := range objs { + obj := &objs[i] off := obj.off base := frame.varp // locals base pointer if off >= 0 { @@ -705,7 +706,7 @@ func adjustframe(frame *stkframe, arg unsafe.Pointer) bool { continue } ptrdata := obj.ptrdata() - gcdata := obj.gcdata + gcdata := obj.gcdata() var s *mspan if obj.useGCProg() { // See comments in mgcmark.go:scanstack @@ -1321,7 +1322,7 @@ func getStackMap(frame *stkframe, cache *pcvalueCache, debug bool) (locals, args // We don't actually use argmap in this case, but we need to fake the stack object // record for these frames which contain an internal/abi.RegArgs at a hard-coded offset. // This offset matches the assembly code on amd64 and arm64. - objs = methodValueCallFrameObjs + objs = methodValueCallFrameObjs[:] } else { p := funcdata(f, _FUNCDATA_StackObjects) if p != nil { @@ -1340,23 +1341,33 @@ func getStackMap(frame *stkframe, cache *pcvalueCache, debug bool) (locals, args return } -var ( - abiRegArgsEface interface{} = abi.RegArgs{} - abiRegArgsType *_type = efaceOf(&abiRegArgsEface)._type - methodValueCallFrameObjs = []stackObjectRecord{ - { - off: -int32(alignUp(abiRegArgsType.size, 8)), // It's always the highest address local. - size: int32(abiRegArgsType.size), - _ptrdata: int32(abiRegArgsType.ptrdata), - gcdata: abiRegArgsType.gcdata, - }, - } -) +var methodValueCallFrameObjs [1]stackObjectRecord // initialized in stackobjectinit -func init() { +func stkobjinit() { + var abiRegArgsEface interface{} = abi.RegArgs{} + abiRegArgsType := efaceOf(&abiRegArgsEface)._type if abiRegArgsType.kind&kindGCProg != 0 { throw("abiRegArgsType needs GC Prog, update methodValueCallFrameObjs") } + // Set methodValueCallFrameObjs[0].gcdataoff so that + // stackObjectRecord.gcdata() will work correctly with it. + ptr := uintptr(unsafe.Pointer(&methodValueCallFrameObjs[0])) + var mod *moduledata + for datap := &firstmoduledata; datap != nil; datap = datap.next { + if datap.gofunc <= ptr && ptr < datap.end { + mod = datap + break + } + } + if mod == nil { + throw("methodValueCallFrameObjs is not in a module") + } + methodValueCallFrameObjs[0] = stackObjectRecord{ + off: -int32(alignUp(abiRegArgsType.size, 8)), // It's always the highest address local. + size: int32(abiRegArgsType.size), + _ptrdata: int32(abiRegArgsType.ptrdata), + gcdataoff: uint32(uintptr(unsafe.Pointer(abiRegArgsType.gcdata)) - mod.rodata), + } } // A stackObjectRecord is generated by the compiler for each stack object in a stack frame. @@ -1365,10 +1376,10 @@ type stackObjectRecord struct { // offset in frame // if negative, offset from varp // if non-negative, offset from argp - off int32 - size int32 - _ptrdata int32 // ptrdata, or -ptrdata is GC prog is used - gcdata *byte // pointer map or GC prog of the type + off int32 + size int32 + _ptrdata int32 // ptrdata, or -ptrdata is GC prog is used + gcdataoff uint32 // offset to gcdata from moduledata.rodata } func (r *stackObjectRecord) useGCProg() bool { @@ -1383,6 +1394,23 @@ func (r *stackObjectRecord) ptrdata() uintptr { return uintptr(x) } +// gcdata returns pointer map or GC prog of the type. +func (r *stackObjectRecord) gcdata() *byte { + ptr := uintptr(unsafe.Pointer(r)) + var mod *moduledata + for datap := &firstmoduledata; datap != nil; datap = datap.next { + if datap.gofunc <= ptr && ptr < datap.end { + mod = datap + break + } + } + // If you get a panic here due to a nil mod, + // you may have made a copy of a stackObjectRecord. + // You must use the original pointer. + res := mod.rodata + uintptr(r.gcdataoff) + return (*byte)(unsafe.Pointer(res)) +} + // This is exported as ABI0 via linkname so obj can call it. // //go:nosplit -- cgit v1.3-5-g9baa