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From: Thiago Adams <thiago.adams@gmail.com>
Newsgroups: comp.lang.c
Subject: Re: question about linker
Date: Wed, 27 Nov 2024 09:57:45 -0300
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On 27/11/2024 09:38, Thiago Adams wrote:
> On 27/11/2024 09:10, Bart wrote:
>> On 27/11/2024 11:57, Bart wrote:
>>> On 27/11/2024 01:52, Thiago Adams wrote:
>>
>>> I also use ILs for my compilers, but I write my own backends. I've 
>>> worked on two diifferent kinds. One looks like a HLL, and only exists 
>>> for my language. So this original source:
>>


I was wondering if is possible to write C programs without struct/union?

I did this experiment.

struct X {
     int a, b;
};

void F1() {
     struct X x;
     x.a = 1;
     x.b = 2;
     printf("%d, %d", x.a, x.b);
}

The equivalent C89 program in a subset without structs count be

#define M(T, obj, OFF) *((T*)(((char*)&(obj)) + (OFF)))

void F2() {
     char x[8];
     M(int, x, 0 /*offset of a*/) = 1;
     M(int, x, 4 /*offset of b*/) = 2;
     printf("\n");
     printf("%d, %d", M(int, x, 0), M(int, x, 4));
}

The char array represents the struct X memory, then we  have to find the 
offset of the members and cast to their types.


Does your IL have structs?

The QBE IL has aggregates types. I think this removes the front end 
calculate the the offsets.

https://c9x.me/compile/doc/il.html#Aggregate-Types