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[Bug target/44532] x86-64 unnecessary parameter extension
- From: "hjl dot tools at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 15 Jun 2010 00:57:43 -0000
- Subject: [Bug target/44532] x86-64 unnecessary parameter extension
- References: <bug-44532-10175@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #3 from hjl dot tools at gmail dot com 2010-06-15 00:57 -------
We should consider:
1. The x86-64 psABI doesn't say how char/short should be extended
as function parameters.
2. Gcc may not touch upper bits, PR 42324.
3. Gcc never depends on the upper bits which are properly extended
in function parameters.
4. Icc may not touch the upper bits in function parameters on stack.
5. For a function without proper prototype, caller may not properly
extend function parameters.
I think the current way is safer.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44532