test_port in run-pass/binops.rs causes valgrind warnings from shape_glue

[msullivan]

On my system, it produces:

==25913== Thread 3:
==25913== Conditional jump or move depends on uninitialised value(s)
==25913==    at 0x5876323: shape::cmp::walk_res2(shape::rust_fn const*, unsigned char const*) (rust_shape.cpp:220)
==25913==    by 0x587A181: shape::ctxt<shape::data<shape::cmp, shape::ptr_pair> >::walk() (rust_shape.h:954)
==25913==    by 0x587A674: shape::data<shape::cmp, shape::ptr_pair>::walk_box_contents1() (rust_shape.cpp:188)
==25913==    by 0x587A6E4: shape::ctxt<shape::data<shape::cmp, shape::ptr_pair> >::walk_box0() (rust_shape.cpp:282)
==25913==    by 0x587A1EC: shape::ctxt<shape::data<shape::cmp, shape::ptr_pair> >::walk() (rust_shape.h:306)
==25913==    by 0x5876F30: shape::cmp::walk_variant2(shape::tag_info&, unsigned long, std::pair<unsigned char const*, unsigned char const*>) (rust_shape.cpp:371)
==25913==    by 0x5876FB7: shape::cmp::walk_tag2(shape::tag_info&, shape::data_pair<unsigned long> const&) (rust_shape.h:1010)
==25913==    by 0x5879B88: shape::data<shape::cmp, shape::ptr_pair>::walk_tag1(shape::tag_info&) (rust_shape.h:1124)
==25913==    by 0x5879CA9: shape::ctxt<shape::data<shape::cmp, shape::ptr_pair> >::walk_tag0() (rust_shape.h:415)
==25913==    by 0x587A034: shape::ctxt<shape::data<shape::cmp, shape::ptr_pair> >::walk() (rust_shape.h:305)
==25913==    by 0x5876DC8: shape_cmp_type (rust_shape.cpp:494)
==25913==    by 0x588056C: ??? (in /home/sully/src/rust/build/x86_64-unknown-linux-gnu/stage1/lib/rustc/x86_64-unknown-linux-gnu/lib/librustrt.so)
==25913== 
==25913== Conditional jump or move depends on uninitialised value(s)
==25913==    at 0x5876330: shape::cmp::walk_res2(shape::rust_fn const*, unsigned char const*) (rust_shape.cpp:209)
==25913==    by 0x587A181: shape::ctxt<shape::data<shape::cmp, shape::ptr_pair> >::walk() (rust_shape.h:954)
==25913==    by 0x587A674: shape::data<shape::cmp, shape::ptr_pair>::walk_box_contents1() (rust_shape.cpp:188)
==25913==    by 0x587A6E4: shape::ctxt<shape::data<shape::cmp, shape::ptr_pair> >::walk_box0() (rust_shape.cpp:282)
==25913==    by 0x587A1EC: shape::ctxt<shape::data<shape::cmp, shape::ptr_pair> >::walk() (rust_shape.h:306)
==25913==    by 0x5876F30: shape::cmp::walk_variant2(shape::tag_info&, unsigned long, std::pair<unsigned char const*, unsigned char const*>) (rust_shape.cpp:371)
==25913==    by 0x5876FB7: shape::cmp::walk_tag2(shape::tag_info&, shape::data_pair<unsigned long> const&) (rust_shape.h:1010)
==25913==    by 0x5879B88: shape::data<shape::cmp, shape::ptr_pair>::walk_tag1(shape::tag_info&) (rust_shape.h:1124)
==25913==    by 0x5879CA9: shape::ctxt<shape::data<shape::cmp, shape::ptr_pair> >::walk_tag0() (rust_shape.h:415)
==25913==    by 0x587A034: shape::ctxt<shape::data<shape::cmp, shape::ptr_pair> >::walk() (rust_shape.h:305)
==25913==    by 0x5876DC8: shape_cmp_type (rust_shape.cpp:494)
==25913==    by 0x588056C: ??? (in /home/sully/src/rust/build/x86_64-unknown-linux-gnu/stage1/lib/rustc/x86_64-unknown-linux-gnu/lib/librustrt.so)
==25913== 

I am commenting out the call to the test_class function and putting in a FIXME that points to this bug.

[msullivan]

Oops. It was actually the test_port function causing the problems.

[catamorphism]

I think I've narrowed down the problem to the code in trans that handles class constructors, which created an 8-bit field within a 64-bit struct field and left three uninitialized bytes (plus, my dodgy shape code for resources wasn't properly skipping over that field (the "drop field"), and was comparing it instead of the actual pointer to the object). Working on a fix.

For future reference, the --track-origins=yes flag to valgrind will actually pinpoint where the uninitialized value was created. Wish I'd known that before I wasted hours barking up the wrong tree :-D

[catamorphism]

I've been working on this, but right now the cycle collector is crashing and I'm not sure I'm getting accurate information from gdb about where. Going to put it aside for a bit, but if someone who knows the RTS better wants to help...

[catamorphism]

Since both shape glue and classes as we know them are supposedly going away, I'm calling this "postponed".

[catamorphism]

I guess this is no longer relevant since comparison ops are now trait-based. binops.rs no longer has a test_port function. Closing.