detached d3eb2c6

feat(syscall): add fixed-arity zero-allocation Syscall6 and Syscall15

commit
d3eb2c6d65215306eb3f38a2e71193aa1768c8b1
author
brice · · 2026-09-27 18:01 UTC
committer
brice · · 2026-09-27 18:45 UTC
parent
f844878
signature
GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email
2 files · +93 -0
Unified
UnifiedSplit
M syscall_bench_test.go +44 -0
@@ -7,6 +7,7 @@ import (
77 "fmt"
88 "os"
99 "path/filepath"
10+ "runtime"
1011 "testing"
1112
1213 "github.com/bnema/purego"
@@ -146,6 +147,49 @@ func BenchmarkCallingMethods(b *testing.B) {
146147 }
147148 })
148149
150+ // Fixed-arity integer calls compared with literal SyscallN arguments.
151+ b.Run("Syscall6", func(b *testing.B) {
152+ b.ReportAllocs()
153+ fn := testCases[3].cFnPtr
154+ var result uintptr
155+ b.ResetTimer()
156+ for range b.N {
157+ result, _, _ = purego.Syscall6(fn, 1, 2, 3, 4, 5, 0)
158+ }
159+ if result != 15 {
160+ b.Fatalf("sum = %d", result)
161+ }
162+ })
163+ b.Run("SyscallNLiteral", func(b *testing.B) {
164+ b.ReportAllocs()
165+ fn := testCases[3].cFnPtr
166+ var result uintptr
167+ b.ResetTimer()
168+ for range b.N {
169+ result, _, _ = purego.SyscallN(fn, 1, 2, 3, 4, 5, 0)
170+ }
171+ if result != 15 {
172+ b.Fatalf("sum = %d", result)
173+ }
174+ })
175+ if runtime.GOOS != "windows" {
176+ b.Run("CallbackInts", func(b *testing.B) {
177+ b.ReportAllocs()
178+ cb := purego.NewCallbackInts(func(a *purego.CallbackArgs) uintptr {
179+ return a.Int(0) + a.Int(1) + a.Int(2) + a.Int(3) + a.Int(4)
180+ })
181+ fn := testCases[3].cCallbackPtr
182+ var result uintptr
183+ b.ResetTimer()
184+ for range b.N {
185+ result, _, _ = purego.Syscall6(fn, cb, 1, 2, 3, 4, 5)
186+ }
187+ if result != 15 {
188+ b.Fatalf("sum = %d", result)
189+ }
190+ })
191+ }
192+
149193 // Benchmark round-trip: Go → C → Go callback (realistic use case)
150194 b.Run("RoundTrip/GoC", func(b *testing.B) {
151195 for _, tc := range testCases {
@@ -7,6 +7,7 @@ import (
7 "fmt"7 "fmt"
8 "os"8 "os"
9 "path/filepath"9 "path/filepath"
10+ "runtime"
10 "testing"11 "testing"
11 12
12 "github.com/bnema/purego"13 "github.com/bnema/purego"
@@ -146,6 +147,49 @@ func BenchmarkCallingMethods(b *testing.B) {
146 }147 }
147 })148 })
148 149
150+ // Fixed-arity integer calls compared with literal SyscallN arguments.
151+ b.Run("Syscall6", func(b *testing.B) {
152+ b.ReportAllocs()
153+ fn := testCases[3].cFnPtr
154+ var result uintptr
155+ b.ResetTimer()
156+ for range b.N {
157+ result, _, _ = purego.Syscall6(fn, 1, 2, 3, 4, 5, 0)
158+ }
159+ if result != 15 {
160+ b.Fatalf("sum = %d", result)
161+ }
162+ })
163+ b.Run("SyscallNLiteral", func(b *testing.B) {
164+ b.ReportAllocs()
165+ fn := testCases[3].cFnPtr
166+ var result uintptr
167+ b.ResetTimer()
168+ for range b.N {
169+ result, _, _ = purego.SyscallN(fn, 1, 2, 3, 4, 5, 0)
170+ }
171+ if result != 15 {
172+ b.Fatalf("sum = %d", result)
173+ }
174+ })
175+ if runtime.GOOS != "windows" {
176+ b.Run("CallbackInts", func(b *testing.B) {
177+ b.ReportAllocs()
178+ cb := purego.NewCallbackInts(func(a *purego.CallbackArgs) uintptr {
179+ return a.Int(0) + a.Int(1) + a.Int(2) + a.Int(3) + a.Int(4)
180+ })
181+ fn := testCases[3].cCallbackPtr
182+ var result uintptr
183+ b.ResetTimer()
184+ for range b.N {
185+ result, _, _ = purego.Syscall6(fn, cb, 1, 2, 3, 4, 5)
186+ }
187+ if result != 15 {
188+ b.Fatalf("sum = %d", result)
189+ }
190+ })
191+ }
192+
149 // Benchmark round-trip: Go → C → Go callback (realistic use case)193 // Benchmark round-trip: Go → C → Go callback (realistic use case)
150 b.Run("RoundTrip/GoC", func(b *testing.B) {194 b.Run("RoundTrip/GoC", func(b *testing.B) {
151 for _, tc := range testCases {195 for _, tc := range testCases {
A syscall_fixed.go +49 -0
@@ -0,0 +1,49 @@
1+// SPDX-License-Identifier: Apache-2.0
2+// SPDX-FileCopyrightText: 2026 The Ebitengine Authors
3+
4+//go:build darwin || freebsd || linux || netbsd || windows
5+
6+package purego
7+
8+import (
9+ "runtime"
10+ "unsafe"
11+)
12+
13+//go:noescape
14+//go:linkname noescapeFixed runtime.noescape
15+func noescapeFixed(p unsafe.Pointer) unsafe.Pointer
16+
17+// Syscall15 calls fn with up to 15 integer-class arguments without
18+// allocating. Unused arguments must be 0. Unlike SyscallN it does not use a
19+// variadic argument slice. Like SyscallN, a uintptr converted from an
20+// unsafe.Pointer in the call expression keeps its object alive and un-moved
21+// for the duration of the call (go:uintptrescapes); the object escapes to
22+// the heap. The C function must not retain the pointer after returning.
23+// Mixed integer/float arguments are not supported, as for SyscallN.
24+//
25+//go:uintptrescapes
26+func Syscall15(fn, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15 uintptr) (r1, r2, err uintptr) {
27+ if fn == 0 {
28+ panic("purego: fn is nil")
29+ }
30+ if runtime.GOOS == "windows" {
31+ return syscall_syscallN(fn, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15)
32+ }
33+ s := syscallArgs{
34+ fn: fn, a1: a1, a2: a2, a3: a3, a4: a4, a5: a5,
35+ a6: a6, a7: a7, a8: a8, a9: a9, a10: a10,
36+ a11: a11, a12: a12, a13: a13, a14: a14, a15: a15,
37+ }
38+ // cgocall is synchronous: s remains on this goroutine's stack until it returns.
39+ runtime_cgocall(syscallXABI0, noescapeFixed(unsafe.Pointer(&s)))
40+ return s.a1, s.a2, s.a3
41+}
42+
43+// Syscall6 is Syscall15 with six arguments. Like Syscall15, pointer-derived
44+// uintptr arguments keep their objects alive and cause them to escape.
45+//
46+//go:uintptrescapes
47+func Syscall6(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
48+ return Syscall15(fn, a1, a2, a3, a4, a5, a6, 0, 0, 0, 0, 0, 0, 0, 0, 0)
49+}
@@ -0,0 +1,49 @@
1+// SPDX-License-Identifier: Apache-2.0
2+// SPDX-FileCopyrightText: 2026 The Ebitengine Authors
3+
4+//go:build darwin || freebsd || linux || netbsd || windows
5+
6+package purego
7+
8+import (
9+ "runtime"
10+ "unsafe"
11+)
12+
13+//go:noescape
14+//go:linkname noescapeFixed runtime.noescape
15+func noescapeFixed(p unsafe.Pointer) unsafe.Pointer
16+
17+// Syscall15 calls fn with up to 15 integer-class arguments without
18+// allocating. Unused arguments must be 0. Unlike SyscallN it does not use a
19+// variadic argument slice. Like SyscallN, a uintptr converted from an
20+// unsafe.Pointer in the call expression keeps its object alive and un-moved
21+// for the duration of the call (go:uintptrescapes); the object escapes to
22+// the heap. The C function must not retain the pointer after returning.
23+// Mixed integer/float arguments are not supported, as for SyscallN.
24+//
25+//go:uintptrescapes
26+func Syscall15(fn, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15 uintptr) (r1, r2, err uintptr) {
27+ if fn == 0 {
28+ panic("purego: fn is nil")
29+ }
30+ if runtime.GOOS == "windows" {
31+ return syscall_syscallN(fn, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12, a13, a14, a15)
32+ }
33+ s := syscallArgs{
34+ fn: fn, a1: a1, a2: a2, a3: a3, a4: a4, a5: a5,
35+ a6: a6, a7: a7, a8: a8, a9: a9, a10: a10,
36+ a11: a11, a12: a12, a13: a13, a14: a14, a15: a15,
37+ }
38+ // cgocall is synchronous: s remains on this goroutine's stack until it returns.
39+ runtime_cgocall(syscallXABI0, noescapeFixed(unsafe.Pointer(&s)))
40+ return s.a1, s.a2, s.a3
41+}
42+
43+// Syscall6 is Syscall15 with six arguments. Like Syscall15, pointer-derived
44+// uintptr arguments keep their objects alive and cause them to escape.
45+//
46+//go:uintptrescapes
47+func Syscall6(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr) {
48+ return Syscall15(fn, a1, a2, a3, a4, a5, a6, 0, 0, 0, 0, 0, 0, 0, 0, 0)
49+}

Keyboard shortcuts

Single-key shortcuts are on. ctrl k and esc work whatever this says.

ctrl k :
go to a section, branch, tag, file or repository
?
this list
j k
move the row cursor down / up
enter
open the row under the cursor; on Files, a directory opens or closes in place
↑ ↓ ← → home end
in the file tree (focus on a row): previous / next row, close / open a directory or go to its parent / first entry, first / last row. They never open a file
l h
on Files: open a directory or a file / close a directory or go up to its parent, then to the parent page. Elsewhere: into the side panel (on a merge request, its files) / back to the content; there j k move between its controls
g g G
first / last row
/
filter the list; on Files, find a file anywhere in the repository (esc clears, enter opens the best match)
b
switch branch or tag
g s g f g c g b g m g i g r g a
tabs: summary, files, commits, branches & tags, merge requests, issues, releases, actions (when available)
g h
home
w
wide mode: use the whole width of the screen, or not (remembered)
y
copy a permalink pinned to the commit
d u x
diff: split / unified / collapse or expand all
e E
diff: the whole file in view / every file, with the lines the hunks hide
n
merge request: next note in the diff
esc
close a dialog, leave a field

Branches 1

Tags 102

↑↓ moveenter openesc close