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[Bug target/46942] x86_64 parameter passing unnecessary sign/zero extends
- From: "hjl.tools at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Sun, 2 Jan 2011 17:58:42 +0000
- Subject: [Bug target/46942] x86_64 parameter passing unnecessary sign/zero extends
- Auto-submitted: auto-generated
- References: <bug-46942-4@http.gcc.gnu.org/bugzilla/>
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.
---