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POTurning on g++ optimization causes segfault - I don't get it
 

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  1. POTurning on g++ optimization causes segfault - I don't get it
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    <p>I've been working on my program, and I decided to turn on some optimizations using <code>g++ -O3</code>. Suddenly, my program started segfaulting. I've hunted the problematic code down, and minimized my program to something that still segfaults (only when using level 3 optimizations). I was hoping someone could take a quick peek at the code (I tried minimizing it as much as possible):</p> <pre><code>// src/main.cpp #include "rt/lights/point.hpp" int main(int argc, char **argv) { rt::Light *light = new rt::light::Point(alg::vector(.0f, 5.0f, 5.0f), rt::Color(1.0f), .5f); return 0; } // include/rt/lights/point.hpp #ifndef RT_LIGHT_POINT_HPP_ #define RT_LIGHT_POINT_HPP_ #include "rt/accelerator.hpp" #include "rt/color.hpp" #include "rt/intersection.hpp" #include "rt/light.hpp" // abstract namespace rt { namespace light { class Point : public Light { public: Point(alg::vector pos, Color color, float intensity) : Light(intensity * color), pos(pos) {} Color get_contrib(const Intersection&amp;, const Accelerator&amp;, const alg::vector&amp; toViewer) const; private: alg::vector pos; }; } // namespace light } // namespace rt #endif // include/rt/light.hpp #ifndef RT_LIGHT_HPP_ #define RT_LIGHT_HPP_ #include "algebra/vector.hpp" #include "rt/color.hpp" namespace rt { class Intersection; class Accelerator; class Light { public: Light(Color intensity) : intensity(intensity) {} virtual Color get_contrib(const Intersection&amp;, const Accelerator&amp;, const alg::vector&amp; toViewer) const = 0; Color get_intensity() const {return intensity;} protected: Color intensity; }; } // namespace rt #endif </code></pre> <p>I would love some insight on why this code only segfaults when using optimizations, and how to stop it from doing so. Thanks!</p> <pre><code>$ find src/ -name "*.cpp" | xargs g++ -I include/ -O3 $ ./a.out Segmentation fault </code></pre> <p>Edit: By request, the constructors for alg::vector</p> <pre> struct vector { float x, y, z; vector() : x(.0f), y(.0f), z(.0f) {} explicit vector(float f) : x(f), y(f), z(f) {} vector(float x, float y, float z) : x(x), y(y), z(z) {} // ... </pre> <p>Edit2: Adding gdb output when compiling with <code>-g</code></p> <pre> (gdb) file a.out Reading symbols from /home/rob/devel/gbug/a.out...done. (gdb) run Starting program: /home/rob/devel/gbug/a.out Program received signal SIGSEGV, Segmentation fault. rt::light::Point::Point (this=0x804b008, pos=..., color=..., intensity=0.5) at src/rt/lights/point.cpp:13 13 Point::Point(alg::vector pos, Color color, float intensity) : Light(intensity * color), pos(pos) (gdb) bt #0 rt::light::Point::Point (this=0x804b008, pos=..., color=..., intensity=0.5) at src/rt/lights/point.cpp:13 #1 0x08048898 in main (argc=1, argv=0xbffff3e4) at src/main.cpp:5 </pre> <p>Edit3: Sources for rt::Color.</p> <pre> // include/rt/color.hpp #ifndef RT_COLOR_HPP_ #define RT_COLOR_HPP_ #include "algebra/vector.hpp" namespace rt { /******************************************************************************* * CLASS DEFINITION */ struct Color { float r, g, b; Color() : r(.0f), g(.0f), b(.0f) {} explicit Color(float f) : r(f), g(f), b(f) {} Color(float r, float g, float b) : r(r), g(g), b(b) {} Color& operator+= (const Color&); Color& operator*= (const Color&); Color& operator*= (float); }; /******************************************************************************* * MEMBER OPERATORS */ inline Color& Color::operator+= (const Color& other) { r += other.r; g += other.g; b += other.b; return *this; } inline Color& Color::operator*= (const Color& other) { r *= other.r; g *= other.g; b *= other.b; return *this; } inline Color& Color::operator*= (float f) { r *= f; g *= f; b *= f; } /******************************************************************************* * ADDITIONAL OPERATORS */ inline Color operator+ (Color lhs, const Color& rhs) { return lhs += rhs; } inline Color operator* (Color lhs, const Color& rhs) { return lhs *= rhs; } inline Color operator* (Color c, float f) { return c *= f; } inline Color operator* (float f, Color c) { return c *= f; } } // namespace rt #endif </pre>
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    1. COHave you tried compiling with -g as well to see if the backtrace is at all usable?
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      1. POTurning on g++ optimization causes segfault - I don't get it
      1. USMark Loeser
    2. COI'm curious why you don't compile with `g++ src/*.cpp -Iinclude -O3`. With the `xargs` approach, the compiler would build each file into `a.out`, so I'm assuming they all have `main()`.
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      1. POTurning on g++ optimization causes segfault - I don't get it
      1. USchrisaycock
    3. COcan you post the copy constructor of `alg::vector`?
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      1. POTurning on g++ optimization causes segfault - I don't get it
      1. USNaveen
 

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