Skip to content

Instantly share code, notes, and snippets.

@SchrodingerZhu

SchrodingerZhu/Gimple.c

Last active November 15, 2024 16:10
Show Gist options

  • Select an option

    Learn more about clone URLs
  • Save SchrodingerZhu/84a334f8666b567800624446d354b568 to your computer and use it in GitHub Desktop.

Select an option

Learn more about clone URLs
Save SchrodingerZhu/84a334f8666b567800624446d354b568 to your computer and use it in GitHub Desktop.
Download ZIP
GCCJIT Bug?
Raw
Gimple.c
struct Lancern;
struct QuaticCat;
struct Float;
union Union;
struct Lancern
{
float professional;
unsigned long genius;
};
struct QuaticCat
{
float excellent;
long magnificent;
};
struct Float
{
__uint32_t mant:23;
__uint32_t exp:8;
__uint32_t sign:1;
};
union Union
{
struct Lancern professional;
struct QuaticCat genius;
struct Float _float;
};
static union Union union_data = (union Union) {.genius=(struct QuaticCat) {.excellent=(float)0.156250, .magnificent=(long)-1}};
extern int
main ()
{
unsigned long %3;
unsigned long %4;
bool %5;
struct Float %7;
__uint32_t %8;
__uint32_t %9;
__uint32_t %10;
__uint32_t %11;
__uint32_t %12;
__uint32_t %13;
bool %14;
bool %15;
bool %16;
bool %17;
bool %18;
int %20;
bb0:
%3 = union_data.professional.genius;
%4 = (unsigned long)-1;
%5 = %3 == %4;
if (%5) goto bb1; else goto bb2;
bb1:
%7 = union_data._float;
%8 = %7.sign:1;
%9 = %7.exp:8;
%10 = %7.mant:23;
%11 = (__uint32_t)0;
%12 = (__uint32_t)124;
%13 = (__uint32_t)2097152;
%14 = %8 == %11;
%15 = %9 == %12;
%16 = %10 == %13;
%17 = %14 && %15;
%18 = %17 && %16;
if (%18) goto bb3; else goto bb2;
bb2:
(void)__builtin_trap ();
goto bb2;
bb3:
%20 = (int)0;
return %20;
}
@SchrodingerZhu
Copy link
Author

SchrodingerZhu commented Nov 15, 2024 •
edited
Loading

Even after I making Float the same size as others by padding long to its tail and utilizing bitcast to to convert union to target struct, the problem still exists.

@SchrodingerZhu
Copy link
Author

SchrodingerZhu commented Nov 15, 2024

Even a simple program like:

struct Int;

struct Int
{
  int A:17;
  int B:5;
  int C:10;
};

static void
from_int_to_bitfield (int %arg0, int %arg1)
{
  int %0;
  int %1;
  struct Int %2;
  int %3;
  bool %4;

bb0:
  %0 = %arg0;
  %1 = %arg1;
  %2 = bitcast(%0, struct Int);
  %3 = %2.A:17;
  %4 = %3 == %1;
  if (%4) goto bb1; else goto bb2;

bb1:
  return;

bb2:
  (void)__builtin_trap ();
  goto bb2;
}

extern int
main ()
{
  int %0;
  int %1;
  int %2;

bb0:
  %0 = (int)-559038737;
  %1 = (int)-16657;
  (void)from_int_to_bitfield (%0, %1);
  %2 = (int)0;
  return %2;
}

will be folded into ud2, which exits normally when the function is not internal

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment