[constrained-value] zero-overhead
One more wish/requirement for cv. Maybe this is already met? I haven't checked. I want to be able to select a policy that does nothing, and on (reasonably modern compilers) achieve performance comparable to the underlying (int) type. That is, I want to use this like logging - where I can switch it off at compile time and make the overhead negligible.
Neal, I just tested this out last night and it already achieves this (on reasonably modern compilers ;-) but you may have to switch from "Debug" mode to "Release" mode, i.e. switch on optimizations. That was with VC++2005. Cheers -- Martin
-----Original Message----- From: boost-bounces@lists.boost.org [mailto:boost-bounces@lists.boost.org] On Behalf Of Neal Becker Sent: 30 August 2007 12:08 To: boost@lists.boost.org Subject: [boost] [constrained-value] zero-overhead
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One more wish/requirement for cv.
Maybe this is already met? I haven't checked.
I want to be able to select a policy that does nothing, and on (reasonably modern compilers) achieve performance comparable to the underlying (int) type. That is, I want to use this like logging - where I can switch it off at compile time and make the overhead negligible.
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Dowie, Martin (SELEX) (UK) wrote:
Neal,
I just tested this out last night and it already achieves this (on reasonably modern compilers ;-)
There should still be some differences, because of the ABI. C++ compilers usually use a mangled C ABI, which behaves differently for struct or class types, even if those have the same size and alignment requirements as some other built-in types.
From: Neal Becker I want to use this like logging - where I can switch it off at compile time and make the overhead negligible.
I wrote a simple test function: int test() { bounded_int<int, -3, 7>::type b(5); b++; b -= 1; return b; } I compiled it with gcc 4.01, optimisations turned on. I had to add explicit 'inline' to several functions, and then the assembler output was as follows: __Z4testv: LFB1019: pushl %ebp LCFI17: movl $5, %eax movl %esp, %ebp LCFI18: popl %ebp ret I dare to say it couldn't be optimised more now... ;-) Best regards, Robert
participants (4)
-
Dowie, Martin (SELEX) (UK) -
Mathias Gaunard -
Neal Becker -
Robert Kawulak