[Bug target/64243] New: Passing and returning structures with single member of floating type via SSE registers is wrong on Windows x86-64 ABI

[krzysztof.surdacki at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64243

            Bug ID: 64243
           Summary: Passing and returning structures with single member of
                    floating type via SSE registers is wrong on Windows
                    x86-64 ABI
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: krzysztof.surdacki at gmail dot com

Two types of structures:

struct TestFloat { float x; };
struct TestDouble { double x; };

are passed and returned via SSE registers which is wrong in Windows x86-64 ABI.
According to Microsoft documentation:
http://msdn.microsoft.com/en-us/library/zthk2dkh.aspx
http://msdn.microsoft.com/en-us/library/7572ztz4.aspx
and code generated by MSVS2013 analysis, this kind of structures should be
passed via integer registers (RCX, RDX, R8, and R9) and returned in RAX
register.