From e2ca417ee797e1e80d8d395e0f4760416b8346d9 Mon Sep 17 00:00:00 2001 From: Than McIntosh Date: Wed, 25 Jan 2023 10:46:08 -0500 Subject: cmd/link: linker portion of dead map removal MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This patch contains the linker changes needed to enable deadcoding of large unreferenced map variables, in combination with a previous compiler change. We add a new cleanup function that runs just after deadcode that looks for relocations in "init" funcs that are weak, of type R_CALL (and siblings), and are targeting an unreachable function. If we find such a relocation, after checking to make sure it targets a map.init.XXX helper, we redirect the relocation to a point to a no-op routine ("mapinitnoop") in the runtime. Compilebench results for this change: │ out.base.txt │ out.wrap.txt │ │ sec/op │ sec/op vs base │ Template 218.6m ± 2% 221.1m ± 1% ~ (p=0.129 n=39) Unicode 180.5m ± 1% 178.9m ± 1% -0.93% (p=0.006 n=39) GoTypes 1.162 ± 1% 1.156 ± 1% ~ (p=0.850 n=39) Compiler 143.6m ± 1% 142.6m ± 1% ~ (p=0.743 n=39) SSA 8.698 ± 1% 8.719 ± 1% ~ (p=0.145 n=39) Flate 142.6m ± 1% 143.9m ± 3% ~ (p=0.287 n=39) GoParser 247.7m ± 1% 248.8m ± 1% ~ (p=0.265 n=39) Reflect 588.0m ± 1% 590.4m ± 1% ~ (p=0.269 n=39) Tar 198.5m ± 1% 201.3m ± 1% +1.38% (p=0.005 n=39) XML 259.1m ± 1% 260.0m ± 1% ~ (p=0.376 n=39) LinkCompiler 746.8m ± 2% 747.8m ± 1% ~ (p=0.706 n=39) ExternalLinkCompiler 1.906 ± 0% 1.902 ± 1% ~ (p=0.207 n=40) LinkWithoutDebugCompiler 522.4m ± 21% 471.1m ± 1% -9.81% (p=0.000 n=40) StdCmd 21.32 ± 0% 21.39 ± 0% +0.32% (p=0.035 n=40) geomean 609.2m 606.0m -0.53% │ out.base.txt │ out.wrap.txt │ │ user-sec/op │ user-sec/op vs base │ Template 401.9m ± 3% 406.9m ± 2% ~ (p=0.291 n=39) Unicode 191.9m ± 6% 196.1m ± 3% ~ (p=0.052 n=39) GoTypes 3.967 ± 3% 4.056 ± 1% ~ (p=0.099 n=39) Compiler 171.1m ± 3% 173.4m ± 3% ~ (p=0.415 n=39) SSA 30.04 ± 4% 30.25 ± 4% ~ (p=0.106 n=39) Flate 246.3m ± 3% 248.9m ± 4% ~ (p=0.499 n=39) GoParser 518.7m ± 1% 520.6m ± 2% ~ (p=0.531 n=39) Reflect 1.670 ± 1% 1.656 ± 2% ~ (p=0.137 n=39) Tar 352.7m ± 2% 360.3m ± 2% ~ (p=0.117 n=39) XML 528.8m ± 2% 521.1m ± 2% ~ (p=0.296 n=39) LinkCompiler 1.128 ± 2% 1.140 ± 2% ~ (p=0.324 n=39) ExternalLinkCompiler 2.165 ± 2% 2.147 ± 2% ~ (p=0.537 n=40) LinkWithoutDebugCompiler 484.2m ± 4% 490.7m ± 3% ~ (p=0.897 n=40) geomean 818.5m 825.1m +0.80% │ out.base.txt │ out.wrap.txt │ │ text-bytes │ text-bytes vs base │ HelloSize 766.0Ki ± 0% 766.0Ki ± 0% ~ (p=1.000 n=40) ¹ CmdGoSize 10.02Mi ± 0% 10.02Mi ± 0% -0.03% (n=40) geomean 2.738Mi 2.738Mi -0.01% ¹ all samples are equal │ out.base.txt │ out.wrap.txt │ │ data-bytes │ data-bytes vs base │ HelloSize 14.17Ki ± 0% 14.17Ki ± 0% ~ (p=1.000 n=40) ¹ CmdGoSize 308.3Ki ± 0% 298.5Ki ± 0% -3.19% (n=40) geomean 66.10Ki 65.04Ki -1.61% ¹ all samples are equal │ out.base.txt │ out.wrap.txt │ │ bss-bytes │ bss-bytes vs base │ HelloSize 197.3Ki ± 0% 197.3Ki ± 0% ~ (p=1.000 n=40) ¹ CmdGoSize 228.2Ki ± 0% 228.1Ki ± 0% -0.01% (n=40) geomean 212.2Ki 212.1Ki -0.01% ¹ all samples are equal │ out.base.txt │ out.wrap.txt │ │ exe-bytes │ exe-bytes vs base │ HelloSize 1.192Mi ± 0% 1.192Mi ± 0% +0.00% (p=0.000 n=40) CmdGoSize 14.85Mi ± 0% 14.83Mi ± 0% -0.09% (n=40) geomean 4.207Mi 4.205Mi -0.05% Also tested for any linker changes by benchmarking relink of k8s "kubelet"; no changes to speak of there. Updates #2559. Updates #36021. Updates #14840. Change-Id: I4cc5370b3f20679a1065aaaf87bdf2881e257631 Reviewed-on: https://go-review.googlesource.com/c/go/+/463395 Run-TryBot: Than McIntosh Reviewed-by: Cherry Mui TryBot-Result: Gopher Robot --- src/cmd/link/internal/ld/deadcode_test.go | 28 +++++++++++++++++----------- 1 file changed, 17 insertions(+), 11 deletions(-) (limited to 'src/cmd/link/internal/ld/deadcode_test.go') diff --git a/src/cmd/link/internal/ld/deadcode_test.go b/src/cmd/link/internal/ld/deadcode_test.go index 573bff3c85..633a0d0bfb 100644 --- a/src/cmd/link/internal/ld/deadcode_test.go +++ b/src/cmd/link/internal/ld/deadcode_test.go @@ -19,14 +19,16 @@ func TestDeadcode(t *testing.T) { tests := []struct { src string - pos, neg string // positive and negative patterns + pos, neg []string // positive and negative patterns }{ - {"reflectcall", "", "main.T.M"}, - {"typedesc", "", "type:main.T"}, - {"ifacemethod", "", "main.T.M"}, - {"ifacemethod2", "main.T.M", ""}, - {"ifacemethod3", "main.S.M", ""}, - {"ifacemethod4", "", "main.T.M"}, + {"reflectcall", nil, []string{"main.T.M"}}, + {"typedesc", nil, []string{"type:main.T"}}, + {"ifacemethod", nil, []string{"main.T.M"}}, + {"ifacemethod2", []string{"main.T.M"}, nil}, + {"ifacemethod3", []string{"main.S.M"}, nil}, + {"ifacemethod4", nil, []string{"main.T.M"}}, + {"globalmap", []string{"main.small", "main.effect"}, + []string{"main.large"}}, } for _, test := range tests { test := test @@ -39,11 +41,15 @@ func TestDeadcode(t *testing.T) { if err != nil { t.Fatalf("%v: %v:\n%s", cmd.Args, err, out) } - if test.pos != "" && !bytes.Contains(out, []byte(test.pos+"\n")) { - t.Errorf("%s should be reachable. Output:\n%s", test.pos, out) + for _, pos := range test.pos { + if !bytes.Contains(out, []byte(pos+"\n")) { + t.Errorf("%s should be reachable. Output:\n%s", pos, out) + } } - if test.neg != "" && bytes.Contains(out, []byte(test.neg+"\n")) { - t.Errorf("%s should not be reachable. Output:\n%s", test.neg, out) + for _, neg := range test.neg { + if bytes.Contains(out, []byte(neg+"\n")) { + t.Errorf("%s should not be reachable. Output:\n%s", neg, out) + } } }) } -- cgit v1.3