The following is causing hog (reduced from imagick SPEC benchmark):

$ cat 1.i
void ConvertImageCommand();
void MagickCommandGenesis();
void MogrifyImages();
void TracePath();

typedef struct {
  double x, y;
} PointInfo;

typedef struct {
  PointInfo point;
} PrimitiveInfo;

int TraceBezier_alpha, TraceBezier_i;
double TraceBezier_weight;
PointInfo *TraceBezier_points;
PrimitiveInfo *TraceBezier_primitive_info;
void DrawImage() { TracePath(); }

void TracePath() {
  double *coefficients;
  PointInfo point;
  long j;
  for (; TraceBezier_i; TraceBezier_i++) {
    point.x = point.y = TraceBezier_alpha = 1.0;
    j = 0;
    for (; j < 4; j++) {
      point.x += TraceBezier_alpha * coefficients[j] *
                 TraceBezier_primitive_info->point.x;
      point.y += TraceBezier_alpha * TraceBezier_primitive_info->point.y;
      TraceBezier_alpha *= TraceBezier_weight;
      TraceBezier_primitive_info++;
    }
    TraceBezier_points[TraceBezier_i] = point;
    TraceBezier_weight += 1.0;
  }
}

void ConvertMain() { MagickCommandGenesis(ConvertImageCommand); }
void ConvertImageCommand() { MogrifyImages(); }
void MogrifyImages() { DrawImage(); }

int main() { return ConvertMain; }

$ gcc 1.i -flto=auto -Ofast  -shared -fPIC
...

likely never finishes :)