All Questions
Tagged with compiler-construction gcc
193 questions
-3
votes
2
answers
78
views
does new compilers turn the source code into a binary or do they just transpile and hand it over to another compiler [closed]
does new compilers (e.g. the rust compiler or zig compiler) turn the source code into another language (e.g. C) and let that languages compiler (e.g. gcc) spit out the exe or do they do everything all ...
0
votes
3
answers
144
views
When inlining a C function, can an optimizing compiler dereference a pointer more times than explicitly written in the source code?
Consider the following code:
int y = 1;
int* p = &y;
inline int f(int x) {
return x + x;
}
int g(void) {
return f(*p);
}
In this code, there is one explicit dereference.
Is a C compiler ...
0
votes
0
answers
21
views
why in calling a function by GCC convention , the passed parameters are stored in a reversed order in the stack
Can you help me answer this question. I have tried to figure this out by myself but didn't succeed. Is it because we don't know the amount of memory the function will use ?
- 25
1
vote
1
answer
134
views
What is the reasoning behind this boilerplate start-up code?
Here's a snippet from disassembled output of a simple program with gcc on Linux:
400478: ff 15 6a 0b 20 00 callq *0x200b6a(%rip) # 600fe8 <__libc_start_main@GLIBC_2.2.5>
...
- 1,269
0
votes
0
answers
267
views
How to compile to RISC-V?
I'm writing the final stage for my compiler to riscv; however, I have run into a minor issue of figuring out what the start point of the program is. Are we guaranteed that the PC starts execution with ...
- 1,269
1
vote
0
answers
58
views
Unknown type name ‘Node’ in the parser file. (Yacc program)
I've been working on a Yacc program (parser.y) to develop a small compiler that handles arithmetic operations. I'm using Yacc (Bison) and Lex tools to generate the parser and lexical analyzer, ...
- 41
0
votes
1
answer
33
views
Where can I find the body of the function pointed to by the function pointer of cfg_hooks in gcc source code？
In gcc cfghooks.cc
void
predict_edge (edge e, enum br_predictor predictor, int probability)
{
if (!cfg_hooks->predict_edge)
internal_error ("%s does not support predict_edge", ...
- 9
2
votes
0
answers
137
views
Write a gcc plugin that inserts macros at the beginning of each function
I understand that I can use __cyg_profile_func_enter and -finstrument-functions to insert code, but is it possible to insert macros by writing a gcc plugin?
Is there any documentation or possibly an ...
- 39
3
votes
0
answers
90
views
With gcc -O3 optimization, why does the loop index's type affect gcc's internal GIMPLE vector constants (but not the final asm)?
I created a struct array, and here is my source code.
#include <stdio.h>
#include <stdlib.h>
#define N 256
typedef struct arc {
int num;
} arc_t;
typedef double cost_t;
typedef ...
- 31
6
votes
3
answers
525
views
Why don't compilers inline everything, analyze it and then generate their own optimized functions?
Problem summary
I'm trying to do an in-memory database with transactions. I'm reaching bottlenecks on compiler level, specifically inlining limit. I don't have much knowledge about compilers and I ...
- 584
0
votes
0
answers
37
views
Which gcc O2 option do this constant folding？
I am not familiar with gcc,this code:
int a=145;int b=267+a;
printf("%d/n",b);
if comiple with no optimize option,will use the "addl" command,but if open O2 option,it will show me ...
- 1,747
0
votes
1
answer
271
views
DWARF output differs between compiler versions
I compile an ELF file including debug info and then read the debug-info back and parse it to get a list of all variables (global variables and class variables) in the RAM. This already works with the ...
- 31
1
vote
1
answer
105
views
Why doesn't the generated GCC code for array allocation and access follow the `movl (%rdx, %rcx, 4), %eax` formula?
I am thinking about how to compile arrays in x86-64 assembly.
I am reading "Computer Systems - A Programmer's Perspective" and the authors give the following formula:
E[i] -> `movl (%rdx,...
- 157
2
votes
3
answers
498
views
Why do compilers perform aliasing if it slows runtime performance?
I've been learning C and computer science topics out of pure interest and it's led me to becoming interested in compilers. Everything I've read tells me that aliasing results in slower assembly output ...
- 141
1
vote
0
answers
118
views
Why does the compiler need the intermediate representations for link time optimization?
My professor mentioned that gcc can be run with -flto. I am wondering why the intermediary (GIMPLE in GCC case) are needed.
Why is the assembly not sufficient?
He mentioned that this allows the ...
