Doesn't detect change to x64 ABI calling convention due to C++ struct definition change #128
Description
Here's a fun issue that I found recently.
In the x64 System V ABI, the calling convention used to pass structs via registers as opposed to via pointers to memory depends on if the struct is considered trivial according to the Itanium C++ ABI.
This means that if you define this struct
struct v {
float a, b;
};
it can be passed in a single SSE register. However, if you add an empty destructor
struct v {
float a, b;
~v() { }
};
then the class becomes non-trivial and it has to be passed via a pointer instead.
This didn't affect ARM32 compilation (the struct was too large for a register) or MIPS32 compilation (only uses pointers), but broke when build for a desktop simulator.