Re: [Tinycc-devel] modern c++ compiler written in C (food for thought)

[Basile Starynkevitch]

On 10/28/2015 05:14 AM, Sergey Korshunoff wrote:
> Hi Basile
>
> > A C++ compiler needs to be optimizing. The C++ language specification sort-of 
> > requires an > > optimizing compiler
> Did you say that a usual C compiler (gcc, clang) can not optimize as a C++ does?
> A tcc compiler is a compiler for a development speedup. A final stage
> can be build by the usual compiler.

No, I was just saying the obvious point that practically speaking the 
C++11 standard is expecting any compiler implementing that standard to 
optimize significantly. A C++ compiler should inline lots of functions 
(including most member functions declared inside a class) and do a lot 
of optimizations (in particular constant folding, some loop unrolling or 
if (true) optimizations, dead code elimination, etc...). I giuess that 
some template expansion cannot happen without optimizations.

Hence a trivial compiler like TinyC (which don't do any serious 
optimization at all, this is why it compiles so fast) won't make sense 
in C++; you cannot code a TinyC++ compiler (which would not have serious 
optimization passes)!

I do know that both GCC & Clang are optimizing a common internal 
representation (e.g. Gimple in GCC) which is the same (or at least 
mostly overlapping) for C or C++ source code.

Notice that GCC even with -O0 is doing *some* optimizations.

Cheers.

--
Basile STARYNKEVITCH         http://starynkevitch.net/Basile/
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