Make translate-c use intermediate AST

[Vexu]

Will implement #6710

[Sirius902]

Will this by chance address #3453?

[andrewrk]

Still working on this? Is there perhaps a way you can start the work in such a way that it doesn't have to be 100% completed before we can start utilizing it? That way we don't have a PR sitting around bit rotting.

[andrewrk]

Closing this old draft - the code is still available and linked from the respective issue description for anyone to reference it. When we tackle this again let's try to do it incrementally so that the whole rework/refactor does not have to get done before we can start merging into master branch.

[Vexu]

This currently doesn't affect translate-c and could be merged as is for aomeone to continue, ci failure was probably unrelated.

[andrewrk]

Ah I see, I will resurrect it and merge then!

[andrewrk]

This is going to make #7920 much easier to update translate-c because the only thing that will have change is the render() function.

[andrewrk]

Looks like the rebase got messed up

[andrewrk]

@Vexu whenever you feel this is ready to merge into ast-memory-layout, go for it

[ehaas]

There is one error happening on this branch that isn't happening with the old translate-c - duplicate non-translatable macros are getting emitted twice as @compileError.

#define FOO 5=2
#define FOO 5=2

produces

pub const FOO = @compileError("unable to translate C expr: unexpected token .Equal"); // ddef.c:4:9
pub const FOO = @compileError("unable to translate C expr: unexpected token .Equal"); // ddef.c:5:9

Previously only one FOO was emitted. This happens to me on MacOS 11.2 when I #include <stdlib.h> due to duplicate definitions of __API_AVAILABLE_PLATFORM_macCatalyst.

[andrewrk]

One thing that will be interesting to test out on this branch, once we get it compiling again, is this benchmark. Here it is on master branch, on my machine:

test.c

#include <windows.h>

(wipe global & local zig caches)

$ perf stat -e cache-misses -e instructions -e cycles ./zig translate-c test.c -target x86_64-windows-gnu -lc >windows_h.zig

 Performance counter stats for './zig translate-c test.c -target x86_64-windows-gnu -lc':

         6,632,603      cache-misses:u                                              
    40,151,754,610      instructions:u            #    1.39  insn per cycle         
    28,980,858,981      cycles:u                                                    

       6.669550308 seconds time elapsed

       6.539106000 seconds user
       0.132778000 seconds sys