Re: [RFC] cleanup patches for strings

From: Denis Vlasenko
Date: Tue Jun 21 2005 - 07:29:25 EST

On Tuesday 21 June 2005 09:58, cutaway@xxxxxxxxxxxxx wrote:
> Examine each case individually...
> Any code that did a "sizeof(foo)" is [very] likely to give different
> results.
> Also, if there are several instances of "foo" being passed around as
> parameter, you may find the generated code gets somewhat worse if "foo" used
> to be a stack based autovar. On x86, the const[] implementation will always
> cause a 5 byte PUSH for a parameter, whereas the autovar pointer
> implementation often will be a shorter 3 byte EBP relative push. With many
> instances of 'foo' usage (or used in a loop), you may be better off paying
> the price of an autovar init during prolog to get the cheaper parm pushes
> later.

But that 3 byte push is fetching data from stack, while 5 byte const push
does not. I ike smaller code, but not _this_ much.

Also this smallish size advantage may be i386-specific only.

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