I’ve been working on a tool (called leaven) to convert LLVM IR (intermediate
representation) to Go. So you can compile C to LLVM with clang, and then
convert the result to Go. It’s actually pretty easy, because LLVM instructions
are such simple operations. But it’s not very readable; given this:
int strcmp(const char *l, const char *r)
{
for (; *l==*r && *l; l++, r++);
return *(unsigned char *)l - *(unsigned char *)r;
}
It produces this:
func strcmp(v0 *byte, v1 *byte) int32 {
var v10, v11, v12, v13 *byte
var v5, v6, v7, v16, v17, v18 bool
var v3, v4, v14, v15, v21, v22 byte
var v23, v24, v25 int32
_, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _ = v3, v4, v5,
v6, v7, v10, v11, v12, v13, v14, v15, v16, v17, v18, v21, v22, v23, v24, v25
v3 = *v0
v4 = *v1
v5 = v3 != v4
v6 = v3 == 0
v7 = v6 || v5
if v7 {
v21, v22 = v3, v4
goto block20
} else {
goto block8
}
block8:
v10, v11 = v1, v0
goto block9
block9:
v12 = (*byte)(unsafe.Pointer(uintptr(unsafe.Pointer(v11)) +
1*unsafe.Sizeof(*(*byte)(nil))))
v13 = (*byte)(unsafe.Pointer(uintptr(unsafe.Pointer(v10)) +
1*unsafe.Sizeof(*(*byte)(nil))))
v14 = *v12
v15 = *v13
v16 = v14 != v15
v17 = v14 == 0
v18 = v17 || v16
if v18 {
goto block19
} else {
v10, v11 = v13, v12
goto block9
}
block19:
v21, v22 = v14, v15
goto block20
block20:
v23 = int32(uint32(v21))
v24 = int32(uint32(v22))
v25 = v23 - v24
return v25
}
But it works!
I’ve never tried it with a C++ program, but once it’s compiled down to LLVM,
there shouldn’t be much difference.
Whether it is anything like what you are looking for depends on your goals for
the translation. (Though it’s almost certainly not complete enough yet.)
If your goal is to produce maintainable Go source that maintains the general
appearance of the C++ original, you will need to build a custom tool that
recognizes the idioms of your codebase and converts them to equivalent Go
idioms, like Russ Cox did for translating the Go compiler. But keep in mind
that he had the unfair advantage that he was translating C written by Go
programmers.
I don’t think a general-purpose tool to convert C or C++ into maintainable Go
is possible. As you handle more of the odd corner cases of C, the output looks
more and more like machine code. Leaven skips that painful journey and produces
asm.go (by analogy with asm.js) from day 1.
Leaven isn’t really ready for general use, but I decided to throw it on GitHub
in response to your question. It’s at https://github.com/andybalholm/leaven
<https://github.com/andybalholm/leaven>, for whatever it’s worth. I haven’t
gotten around to adding a README or a license, but I’m planning to use the MIT
license.
Andy
> On Jan 2, 2019, at 8:03 PM, Ian Lance Taylor <[email protected]> wrote:
>
> On Wed, Jan 2, 2019 at 7:37 PM <[email protected]> wrote:
>>
>> I have C++ 11 source files which I need to convert to Go language code
>> Is there any converter tool for this.
>> I google quite a few tools, none seems powerful and complete enough to do
>> the job.for me.
>
> C++ 11 is a much more complex language than Go. I think that if you
> want to support all the features of C++11 this would essentially
> require writing a C++11 compiler that generates Go code as its output.
> I don't know of any such tool.
>
> Ian
>
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