Stowage/go
2
0
Fork 0
mirror of https://github.com/golang/go.git synced 2025-12-08 06:10:04 +00:00
Code Issues Projects Releases Packages Wiki Activity

cmd/link, cmd/cgo: support -flto in CFLAGS

Browse source 
The linker now accepts unrecognized object files in external linking mode.
These objects will simply be passed to the external linker.
This permits using -flto which can generate pure byte code objects,
whose symbol table the linker does not know how to read.

The cgo tool now passes -fno-lto when generating objects whose symbols
it needs to read. The cgo tool now emits matching types in different
objects, so that the lto linker does not report a mismatch.

This is based on https://golang.org/cl/293290 by Derek Parker.

For #43505
Fixes #43830
Fixes #46295

Change-Id: I6787de213417466784ddef5af8899e453b4ae1ad
Reviewed-on: https://go-review.googlesource.com/c/go/+/322614
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Hudson-Doyle <michael.hudson@canonical.com>
This commit is contained in:
Ian Lance Taylor 2021-05-25 16:31:41 -07:00
parent 272552275f
commit 24e9707cbf
8 changed files with 140 additions and 15 deletions
Download patch file Download diff file Expand all files Collapse all files

16
src/cmd/cgo/out.go
View file

@ -168,8 +168,18 @@ func (p *Package) writeDefs() {
if *gccgo {
fmt.Fprintf(fc, "extern byte *%s;\n", n.C)
} else {
fmt.Fprintf(fm, "extern char %s[];\n", n.C)
fmt.Fprintf(fm, "void *_cgohack_%s = %s;\n\n", n.C, n.C)
// Force a reference to all symbols so that
// the external linker will add DT_NEEDED
// entries as needed on ELF systems.
// Treat function variables differently
// to avoid type confict errors from LTO
// (Link Time Optimization).
if n.Kind == "fpvar" {
fmt.Fprintf(fm, "extern void %s();\n", n.C)
} else {
fmt.Fprintf(fm, "extern char %s[];\n", n.C)
fmt.Fprintf(fm, "void *_cgohack_%s = %s;\n\n", n.C, n.C)
}
fmt.Fprintf(fgo2, "//go:linkname __cgo_%s %s\n", n.C, n.C)
fmt.Fprintf(fgo2, "//go:cgo_import_static %s\n", n.C)
fmt.Fprintf(fgo2, "var __cgo_%s byte\n", n.C)
@ -1042,7 +1052,7 @@ func (p *Package) writeExports(fgo2, fm, fgcc, fgcch io.Writer) {
// This unpacks the argument struct above and calls the Go function.
fmt.Fprintf(fgo2, "func _cgoexp%s_%s(a *%s) {\n", cPrefix, exp.ExpName, gotype)
fmt.Fprintf(fm, "int _cgoexp%s_%s;\n", cPrefix, exp.ExpName)
fmt.Fprintf(fm, "void _cgoexp%s_%s(void* p){}\n", cPrefix, exp.ExpName)
if gccResult != "void" {
// Write results back to frame.