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Fix for PhantomNode packing in MSVC

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Changed bool to uint32_t in bit fields to have 4-byte packings for 32 bits:
"c++ compilers will allocate bit-fields in memory as follows:
several consecutive bit-field members of the same type will
be allocated sequentially. As soon as a new type needs to be allocated,
it will be aligned with the beginning of the next logical memory block."

References:
- https://msdn.microsoft.com/en-us/library/ewwyfdbe.aspx
- http://stackoverflow.com/questions/308364/c-bitfield-packing-with-bools/308383#308383
This commit is contained in:
Michael Krasnyk 2016-04-24 14:06:48 +02:00
parent dac2f93383
commit 4363fd64c4
3 changed files with 6 additions and 24 deletions
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11
include/engine/hint.hpp
View File

@ -63,18 +63,9 @@ struct Hint
friend std::ostream &operator<<(std::ostream &, const Hint &); friend std::ostream &operator<<(std::ostream &, const Hint &);
}; };
#ifndef _MSC_VER
static_assert(sizeof(Hint) == 60 + 4, "Hint is bigger than expected"); static_assert(sizeof(Hint) == 60 + 4, "Hint is bigger than expected");
constexpr std::size_t ENCODED_HINT_SIZE = 88; constexpr std::size_t ENCODED_HINT_SIZE = 88;
static_assert(ENCODED_HINT_SIZE / 4 * 3 >= sizeof(Hint), static_assert(ENCODED_HINT_SIZE / 4 * 3 >= sizeof(Hint), "ENCODED_HINT_SIZE does not match size of Hint");
"ENCODED_HINT_SIZE does not match size of Hint");
#else
// PhantomNode is bigger under windows because MSVC does not support bit packing
static_assert(sizeof(Hint) == 72 + 4, "Hint is bigger than expected");
constexpr std::size_t ENCODED_HINT_SIZE = 104;
static_assert(ENCODED_HINT_SIZE / 4 * 3 >= sizeof(Hint),
"ENCODED_HINT_SIZE does not match size of Hint");
#endif
} }
} }

12
include/engine/phantom_node.hpp
View File

@ -149,13 +149,11 @@ struct PhantomNode
unsigned reverse_packed_geometry_id; unsigned reverse_packed_geometry_id;
struct ComponentType struct ComponentType
{ {
uint32_t id : 31; std::uint32_t id : 31;
bool is_tiny : 1; std::uint32_t is_tiny : 1;
} component; } component;
// bit-fields are broken on Windows
#ifndef _MSC_VER
static_assert(sizeof(ComponentType) == 4, "ComponentType needs to be 4 bytes big"); static_assert(sizeof(ComponentType) == 4, "ComponentType needs to be 4 bytes big");
#endif
util::Coordinate location; util::Coordinate location;
util::Coordinate input_location; util::Coordinate input_location;
unsigned short fwd_segment_position; unsigned short fwd_segment_position;
@ -165,11 +163,7 @@ struct PhantomNode
extractor::TravelMode backward_travel_mode; extractor::TravelMode backward_travel_mode;
}; };
#ifndef _MSC_VER
static_assert(sizeof(PhantomNode) == 60, "PhantomNode has more padding then expected"); static_assert(sizeof(PhantomNode) == 60, "PhantomNode has more padding then expected");
#else
static_assert(sizeof(PhantomNode) == 72, "PhantomNode has more padding then expected");
#endif
using PhantomNodePair = std::pair<PhantomNode, PhantomNode>; using PhantomNodePair = std::pair<PhantomNode, PhantomNode>;

7
include/util/typedefs.hpp
View File

@ -71,13 +71,10 @@ struct SegmentID
BOOST_ASSERT(!enabled || id != SPECIAL_SEGMENTID); BOOST_ASSERT(!enabled || id != SPECIAL_SEGMENTID);
} }
NodeID id : 31; NodeID id : 31;
bool enabled : 1; std::uint32_t enabled : 1;
}; };
// bit-fields are broken on Windows
#ifndef _MSC_VER
static_assert(sizeof(SegmentID) == 4, "SegmentID needs to be 4 bytes big"); static_assert(sizeof(SegmentID) == 4, "SegmentID needs to be 4 bytes big");
#endif
#endif /* TYPEDEFS_H */ #endif /* TYPEDEFS_H */