Question

I have one huge C file. Within the file, there is a giant struct (~>1million lines). Is there a way to parallel compile this file using additional cores?

Edit: Sorry, after reviewing my code and my question, the actual giant thing is not “struct”, rather, it’s the struct array…

Answer 1

If it is the struct definition that is over 1 million lines, then you’re probably out of luck.

But if you’re declaring a struct variable that is an array of that struct type that is many lines (or not an array but just a very big struct) then I would suggest placing the variable declaration in a separate .c file by itself and using the extern keyword in any other c file that needs to access it. That way it will only need to be re-compiled when it changes.

For example if you had the following:

//Filename: onefile.c

struct _bigStruct{
  int type;
  char *name;
}bigStruct[] = {
  {  1, "One" },
  {  2, "Two" },
  {  3, "Three" },
  {  4, "Four" },
  ...
};

int someFunction(int j, int x)
{
  if (j == bigStruct[x])
     //do something
}

Then I would change it to the following:

//Filename: bigstruct.h
struct _bigStruct{
  int type;
  char *name;
};

and

//Filename: bigstruct.c
struct _bigStruct bigStruct[] = {
{  1, "One" },
{  2, "Two" },
{  3, "Three" },
{  4, "Four" },
...
};

and

//Filename: main.c
#include "bigstruct.h"

extern struct _bigStruct bigStruct[];

int someFunction(int j, int x)
{
  if (j == bigStruct[x].type)
     //do something
}