Adds/changes some types in the ByVal cc test so that they aren't all
structs of arrays of bytes, and adds testing for passing multiple
ByVal arguments.
The zero sized structs force creation of a stack object of size 1, align
8 in the locals area, but otherwise have no effect on the calling convention
code. i.e. They consume no registers or stack space in the paramater save area.
The 32-bit codegen has 8 bytes of padding to fit the new stack object so
stack size stays the same. 64-bit codegen has no padding in the stack
frames allocated so 8 bytes is added, and becuase of 16-byte aligned
stack, the stack size increases from 112 bytes to 128.
This is the first of a series of patches that adds caller support for
by-value arguments. This patch add support for arguments that are passed in a
single GPR.
There are 3 limitation cases:
-The by-value argument is larger than a single register.
-There are no remaining GPRs even though the by-value argument would
otherwise fit in a single GPR.
-The by-value argument requires alignment greater than register width.
Future patches will be required to add support for these cases as well
as for the callee handling (in LowerFormalArguments_AIX) that
corresponds to this work.
Differential Revision: https://reviews.llvm.org/D75863
Sean Fertile