[cfe-users] Porting preprocessor macros to be compatible with clang

[Forumer 4umer via cfe-users]

Hello,

I am sorry to ask for some help on this subject but I am not very 
comfortable with preprocessor and especially with the differences 
between compilers.
We have some (ugly) macros used to generate some data structures and 
methods that works fine on Visual but I would like to use clang to get 
better errors messages

and to compare the compilation time.
So I have created a repository to reproduce the problem and if someone 
could give me some help...
There is only one cpp file so a simple clang++ TestClang.cpp is enough 
to reproduce.

The repository is here: https://github.com/vrichomme/FixMacroOnClang.git

Thanks.
___
cfe-users mailing list
cfe-users@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-users

Re: [cfe-users] How to get code for a function template specialization

[Romulo via cfe-users]

Now I'm facing a second problem. I am able to generate the template
function bodies using print, but I can't seem to be able to locate the
CallExpr inside the printed bodies (the spelling locations point to the non
specialized template). I need this because I might have a template function
calling another function, and I need to write both of them (and replace
their calling names).

Example:

template < typename T >
T add(T x, T y) {
  return x + y;
}

template < typename T >
T mul(T x, T y) {
  return x * y;
}

template < typename T >
T test(T a, T x, T b) {
  return add(mul(a,x), b);
}

int main() {
  std::cout << test(2, 3, 4) << std::endl;
}

--
What I wanted to print:
--

int add_int(int x, int y) {
  return x + y;
}

int mul_int(int x, int y) {
  return x * y;
}

int test_int(int a, int x, int b) {
  return add_int(mul_int(a,x), b);
}

int main() {
  std::cout << test_int(2, 3, 4) << std::endl;
}

When generating the source for test, I can call clang again and recursively
expand each function but that's undesirable and probably slow. I could also
parse generated expressions, but that could lead to errors. And finally I
though about getting in the way of printing (and printing my own names on
CallExpr) or to modify the AST itself but I have no idea how to do that.

Thanks once again.




On Wed, Aug 7, 2019 at 5:58 PM Romulo  wrote:

> Thanks, this solved my problem!
>
> On Sun, Aug 4, 2019 at 11:07 PM Richard Smith 
> wrote:
>
>> On Fri, 2 Aug 2019 at 15:05, Romulo via cfe-users <
>> cfe-users@lists.llvm.org> wrote:
>>
>>> Hello there, thanks for your time reading this :)
>>>
>>> I am trying to extract the code for a specialized template function, but
>>> I have no idea on how to proceed. I know I can use SourceManager to get the
>>> original 'pure template' code but I don't know how to access the
>>> specialized functions (the SourceLocation for them points to the original
>>> function in the AST). My idea is to allow users to write some sugar code
>>> like:
>>>
>>> template 
>>> T myAdd(T x, T y) {
>>>   return x + y;
>>> }
>>>
>>> myAdd< double >(5.5, 3.3);
>>> or
>>> myAdd(1, 2);
>>>
>>> and after parsing their source files, generate the specialized functions
>>> with a different name in a separated utility file, replacing the
>>> occurrences of of use (that's the easy part).
>>> The utility file would look like:
>>>
>>> double _impl_double_myAdd(double x, double y) {
>>>   return x + y;
>>> }
>>>
>>> int _impl_int_myAdd(int x, int y) {
>>>   return x + y;
>>> }
>>>
>>> and the calls:
>>>
>>> _impl_double_myAdd(5.5, 3.3);
>>> and
>>> _impl_int_myAdd(1, 2);
>>>
>>> Can anyone point me in the right direction? I though about just
>>> replacing the usage cases of 'T' but that seems really manual and error
>>> prone.
>>>
>>
>> You can call clang::Decl::print
>> 
>> on the template specialization declaration to see what it looks like after
>> substitution. We don't guarantee that the output will be valid C++ code in
>> all cases (and in fact, there are some constructs that can be produced by
>> template instantiation and cannot be written directly in C++, but they're
>> generally very rare), but it usually will be.
>>
>> If you want a sample of what that looks like, try compiling your code
>> with "-Xclang -ast-print -S -o -"
>>
>> For your original example (with the calls to myAdd moved to a function
>> f()), I get this with clang trunk:
>>
>> template  T myAdd(T x, T y) {
>> return x + y;
>> }
>> template<> double myAdd(double x, double y) {
>> return x + y;
>> }
>> template<> int myAdd(int x, int y) {
>> return x + y;
>> }
>> void f() {
>> myAdd(5.5, 3.2998);
>> myAdd(1, 2);
>> }
>>
>> Example case where the output is not valid C++:
>>
>> template 
>> void destroy(T &t) { t.~T(); }
>> void f(int n) { destroy(n); }
>>
>> ... produces ...
>>
>> template  void destroy(T &t) {
>> t.~T();
>> }
>> template<> void destroy(int &t) {
>> t.~int(); // this won't parse
>> }
>> void f(int n) {
>> destroy(n);
>> }
>>
>
___
cfe-users mailing list
cfe-users@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-users

Re: [cfe-users] Porting preprocessor macros to be compatible with clang

[Matthew Fernandez via cfe-users]

> On Aug 20, 2019, at 07:27, Forumer 4umer via cfe-users 
>  wrote:
> 
> Hello,
> 
> I am sorry to ask for some help on this subject but I am not very comfortable 
> with preprocessor and especially with the differences between compilers.
> We have some (ugly) macros used to generate some data structures and methods 
> that works fine on Visual but I would like to use clang to get better errors 
> messages
> and to compare the compilation time.
> So I have created a repository to reproduce the problem and if someone could 
> give me some help...
> There is only one cpp file so a simple clang++ TestClang.cpp is enough to 
> reproduce.
> The repository is here: https://github.com/vrichomme/FixMacroOnClang.git 
> 

I think you’re going to have to give us more information about what the problem 
is that you’re seeing and what is the behaviour you expected.___
cfe-users mailing list
cfe-users@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-users