From d20e688fcff2e5cc0d5fcc85dc5cc69ce92f919b Mon Sep 17 00:00:00 2001 From: qmuntal Date: Wed, 8 Feb 2023 16:51:34 +0100 Subject: [PATCH] runtime: remove implicit NOFRAME heuristic support All amd64 OSes already make use of the NOFRAME flag wherever is required, so we can remove the frameless nosplit functions heuristic code path. Updates #58378 Change-Id: I966970693ba07f8c66da0aca83c23caad7cbbfe5 Reviewed-on: https://go-review.googlesource.com/c/go/+/466458 Reviewed-by: Cherry Mui Run-TryBot: Quim Muntal TryBot-Result: Gopher Robot Reviewed-by: Than McIntosh --- src/cmd/internal/obj/x86/obj6.go | 16 ++-------------- src/runtime/textflag.h | 1 - 2 files changed, 2 insertions(+), 15 deletions(-) diff --git a/src/cmd/internal/obj/x86/obj6.go b/src/cmd/internal/obj/x86/obj6.go index 395a0a79196509..fc0a9c44848bfa 100644 --- a/src/cmd/internal/obj/x86/obj6.go +++ b/src/cmd/internal/obj/x86/obj6.go @@ -614,27 +614,15 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) { } } - var usefpheuristic bool - switch ctxt.Headtype { - case objabi.Hwindows, objabi.Hdarwin, objabi.Hlinux, objabi.Hdragonfly, - objabi.Hfreebsd, objabi.Hnetbsd, objabi.Hopenbsd, objabi.Hsolaris, objabi.Hplan9: - default: - usefpheuristic = true - } - var bpsize int if ctxt.Arch.Family == sys.AMD64 && !p.From.Sym.NoFrame() && // (1) below - !(autoffset == 0 && p.From.Sym.NoSplit() && usefpheuristic) && // (2) below - !(autoffset == 0 && !hasCall) { // (3) below + !(autoffset == 0 && !hasCall) { // (2) below // Make room to save a base pointer. // There are 2 cases we must avoid: // 1) If noframe is set (which we do for functions which tail call). - // 2) Scary runtime internals which would be all messed up by frame pointers. - // We detect these using a heuristic: frameless nosplit functions. - // TODO: Maybe someday we label them all with NOFRAME and get rid of this heuristic. // For performance, we also want to avoid: - // 3) Frameless leaf functions + // 2) Frameless leaf functions bpsize = ctxt.Arch.PtrSize autoffset += int32(bpsize) p.To.Offset += int64(bpsize) diff --git a/src/runtime/textflag.h b/src/runtime/textflag.h index 214075e360ceb6..893031220120c1 100644 --- a/src/runtime/textflag.h +++ b/src/runtime/textflag.h @@ -28,7 +28,6 @@ #define TLSBSS 256 // Do not insert instructions to allocate a stack frame for this function. // Only valid on functions that declare a frame size of 0. -// TODO(mwhudson): only implemented for ppc64x at present. #define NOFRAME 512 // Function can call reflect.Type.Method or reflect.Type.MethodByName. #define REFLECTMETHOD 1024