Re: [Xen-devel] [patch] pagetable cleanups

[Hollis Blanchard <hollisb@xxxxxxxxxx>]

On Thu, 2005-04-14 at 14:07 -0500, Anthony Liguori wrote:
> On Thu, 2005-04-14 at 13:27, Hollis Blanchard wrote:
> > So no memcpys at all; the caller fills in the values directly into the
> > callee's struct.
> 
> Unless you're dealing with struct assignments.  You basically get a
> memcpy() when you assign structs.

I have attached my testcase. Compile with -c and disassemble the object
file.

It is certainly possible that the callee could create a temporary struct
on its stack and memcpy into the address provided by the ABI. However,
even at -O0 the address of the struct is popped off the stack and used
directly when assigning to structure fields. I'm using gcc 3.3.5.

-- 
Hollis Blanchard
IBM Linux Technology Center

Attachment: ctest.c
Description: Text Data

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