go/src/cmd/compile/internal/gc/sizeof_test.go

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// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package gc
import (
"reflect"
"testing"
"unsafe"
)
// Assert that the size of important structures do not change unexpectedly.
func TestSizeof(t *testing.T) {
const _64bit = unsafe.Sizeof(uintptr(0)) == 8
var tests = []struct {
val interface{} // type as a value
_32bit uintptr // size on 32bit platforms
_64bit uintptr // size on 64bit platforms
}{
cmd/compile, cmd/link, runtime: make defers low-cost through inline code and extra funcdata Generate inline code at defer time to save the args of defer calls to unique (autotmp) stack slots, and generate inline code at exit time to check which defer calls were made and make the associated function/method/interface calls. We remember that a particular defer statement was reached by storing in the deferBits variable (always stored on the stack). At exit time, we check the bits of the deferBits variable to determine which defer function calls to make (in reverse order). These low-cost defers are only used for functions where no defers appear in loops. In addition, we don't do these low-cost defers if there are too many defer statements or too many exits in a function (to limit code increase). When a function uses open-coded defers, we produce extra FUNCDATA_OpenCodedDeferInfo information that specifies the number of defers, and for each defer, the stack slots where the closure and associated args have been stored. The funcdata also includes the location of the deferBits variable. Therefore, for panics, we can use this funcdata to determine exactly which defers are active, and call the appropriate functions/methods/closures with the correct arguments for each active defer. In order to unwind the stack correctly after a recover(), we need to add an extra code segment to functions with open-coded defers that simply calls deferreturn() and returns. This segment is not reachable by the normal function, but is returned to by the runtime during recovery. We set the liveness information of this deferreturn() to be the same as the liveness at the first function call during the last defer exit code (so all return values and all stack slots needed by the defer calls will be live). I needed to increase the stackguard constant from 880 to 896, because of a small amount of new code in deferreturn(). The -N flag disables open-coded defers. '-d defer' prints out the kind of defer being used at each defer statement (heap-allocated, stack-allocated, or open-coded). Cost of defer statement [ go test -run NONE -bench BenchmarkDefer$ runtime ] With normal (stack-allocated) defers only: 35.4 ns/op With open-coded defers: 5.6 ns/op Cost of function call alone (remove defer keyword): 4.4 ns/op Text size increase (including funcdata) for go binary without/with open-coded defers: 0.09% The average size increase (including funcdata) for only the functions that use open-coded defers is 1.1%. The cost of a panic followed by a recover got noticeably slower, since panic processing now requires a scan of the stack for open-coded defer frames. This scan is required, even if no frames are using open-coded defers: Cost of panic and recover [ go test -run NONE -bench BenchmarkPanicRecover runtime ] Without open-coded defers: 62.0 ns/op With open-coded defers: 255 ns/op A CGO Go-to-C-to-Go benchmark got noticeably faster because of open-coded defers: CGO Go-to-C-to-Go benchmark [cd misc/cgo/test; go test -run NONE -bench BenchmarkCGoCallback ] Without open-coded defers: 443 ns/op With open-coded defers: 347 ns/op Updates #14939 (defer performance) Updates #34481 (design doc) Change-Id: I63b1a60d1ebf28126f55ee9fd7ecffe9cb23d1ff Reviewed-on: https://go-review.googlesource.com/c/go/+/202340 Reviewed-by: Austin Clements <austin@google.com>
2019-06-24 12:59:22 -07:00
{Func{}, 124, 224},
{Name{}, 32, 56},
{Param{}, 24, 48},
cmd/compile: move Node.Class to flags Put it at position zero, since it is fairly hot. This shrinks gc.Node into a smaller size class on 64 bit systems. name old time/op new time/op delta Template 193ms ± 5% 192ms ± 3% ~ (p=0.353 n=94+93) Unicode 86.1ms ± 5% 85.0ms ± 4% -1.23% (p=0.000 n=95+98) GoTypes 546ms ± 3% 544ms ± 4% -0.40% (p=0.007 n=94+97) Compiler 2.56s ± 3% 2.54s ± 3% -0.67% (p=0.000 n=99+97) SSA 5.13s ± 2% 5.10s ± 3% -0.55% (p=0.000 n=94+98) Flate 122ms ± 6% 121ms ± 4% -0.75% (p=0.002 n=97+95) GoParser 144ms ± 5% 144ms ± 4% ~ (p=0.298 n=98+97) Reflect 348ms ± 4% 349ms ± 4% ~ (p=0.350 n=98+97) Tar 105ms ± 5% 104ms ± 5% ~ (p=0.154 n=96+98) XML 200ms ± 5% 198ms ± 4% -0.71% (p=0.015 n=97+98) [Geo mean] 330ms 328ms -0.52% name old user-time/op new user-time/op delta Template 229ms ±11% 224ms ± 7% -2.16% (p=0.001 n=100+87) Unicode 109ms ± 5% 109ms ± 6% ~ (p=0.897 n=96+91) GoTypes 712ms ± 4% 709ms ± 4% ~ (p=0.085 n=96+98) Compiler 3.41s ± 3% 3.36s ± 3% -1.43% (p=0.000 n=98+98) SSA 7.46s ± 3% 7.31s ± 3% -2.02% (p=0.000 n=100+99) Flate 145ms ± 6% 143ms ± 6% -1.11% (p=0.001 n=99+97) GoParser 177ms ± 5% 176ms ± 5% -0.78% (p=0.018 n=95+95) Reflect 432ms ± 7% 435ms ± 9% ~ (p=0.296 n=100+100) Tar 121ms ± 7% 121ms ± 5% ~ (p=0.072 n=100+95) XML 241ms ± 4% 239ms ± 5% ~ (p=0.085 n=97+99) [Geo mean] 413ms 410ms -0.73% name old alloc/op new alloc/op delta Template 38.4MB ± 0% 37.7MB ± 0% -1.85% (p=0.008 n=5+5) Unicode 30.1MB ± 0% 28.8MB ± 0% -4.09% (p=0.008 n=5+5) GoTypes 112MB ± 0% 110MB ± 0% -1.69% (p=0.008 n=5+5) Compiler 470MB ± 0% 461MB ± 0% -1.91% (p=0.008 n=5+5) SSA 1.13GB ± 0% 1.11GB ± 0% -1.70% (p=0.008 n=5+5) Flate 25.0MB ± 0% 24.6MB ± 0% -1.67% (p=0.008 n=5+5) GoParser 31.6MB ± 0% 31.1MB ± 0% -1.66% (p=0.008 n=5+5) Reflect 77.1MB ± 0% 75.8MB ± 0% -1.69% (p=0.008 n=5+5) Tar 26.3MB ± 0% 25.7MB ± 0% -2.06% (p=0.008 n=5+5) XML 41.9MB ± 0% 41.1MB ± 0% -1.93% (p=0.008 n=5+5) [Geo mean] 73.5MB 72.0MB -2.03% name old allocs/op new allocs/op delta Template 383k ± 0% 383k ± 0% ~ (p=0.690 n=5+5) Unicode 343k ± 0% 343k ± 0% ~ (p=0.841 n=5+5) GoTypes 1.16M ± 0% 1.16M ± 0% ~ (p=0.310 n=5+5) Compiler 4.43M ± 0% 4.42M ± 0% -0.17% (p=0.008 n=5+5) SSA 9.85M ± 0% 9.85M ± 0% ~ (p=0.310 n=5+5) Flate 236k ± 0% 236k ± 1% ~ (p=0.841 n=5+5) GoParser 320k ± 0% 320k ± 0% ~ (p=0.421 n=5+5) Reflect 988k ± 0% 987k ± 0% ~ (p=0.690 n=5+5) Tar 252k ± 0% 251k ± 0% ~ (p=0.095 n=5+5) XML 399k ± 0% 399k ± 0% ~ (p=1.000 n=5+5) [Geo mean] 741k 740k -0.07% Change-Id: I9e952b58a98e30a12494304db9ce50d0a85e459c Reviewed-on: https://go-review.googlesource.com/41797 Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Reviewed-by: Marvin Stenger <marvin.stenger94@gmail.com>
2017-04-25 18:14:12 -07:00
{Node{}, 76, 128},
}
for _, tt := range tests {
want := tt._32bit
if _64bit {
want = tt._64bit
}
got := reflect.TypeOf(tt.val).Size()
if want != got {
t.Errorf("unsafe.Sizeof(%T) = %d, want %d", tt.val, got, want)
}
}
}