[Bug target/46942] x86_64 parameter passing unnecessary sign/zero extends

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46942

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Depends on|                            |42324

--- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> 2011-01-02 17:58:18 UTC ---
I proposed to update x86-64 psABI with

---
When a value of type _Bool is returned in a register, bit 0 contains the truth
value and bits 1 to 7 shall be zero. When an argument of type _Bool is passed
in a register or on the stack, bit 0 contains the truth value and bits
1 to 31 shall be
zero.

When a value of type signed/unsigned char or short is returned in a register,
bits 0 to 7 for char and bits 0 to 15 for short contain the value and other
bits are left unspecified. When an argument of signed/unsigned type char or
short is passed in a register or on the stack, it shall be sign/zero extended
to
signed/unsigned int.
---