add_ssaaaa and C++

Gabriel Dos Reis gdr at
Mon May 23 00:44:15 CEST 2005

Emmanuel Thomé <Emmanuel.Thome at> writes:

| On Sun, May 22, 2005 at 01:14:54PM +0200, Torbjorn Granlund wrote:
| >   
| > I think this was made with the idea to make sure we'd get the
| > right instruction variants even it the macro is fed with smaller
| > types.
| > 
| > But that reasoning really doesn't make sense.  And we don't seem
| > to be casting lvalues in other places in longlong.h.
| > Furthermore, modern gcc pukes on code trying a non-noop lvalue
| > cast:
| > 
| > /home/tege/addas.c: In function `foo':
| > /home/tege/addas.c:9: error: invalid lvalue in asm statement
| > /home/tege/addas.c:9: error: invalid lvalue in asm statement
| right. the nasty thing is that with g++, casting int& to long& in an asm
| output, even though these types have the same width on i386, gives no
| warning but produces rubbish code. Marvelous.

You can rant as you like but, the compiler is just doing its job of
following instructions.  The cast is understood as
reinterpret_cas<long&>(lvalue_oftype_int) -- which in C speak would be
(long *) (expression with type int*). 
Now, do you want the compiler warn that too?

-- Gaby

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