Re: patch: promoting complex modes (plus splitting complex args)

[kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)]

    The culprit is in the code expanding PARM_DECLs which falls through to
    the RESULT_DECL case, particularly because we only handle promotions
    of REG:

My first question would be when did we start promoting FP modes and what
sense does that make?

The reason I added promoted modes to GCC was for a case where a machine did
not have instructions in a smaller integer mode, such as a byte.  That
would mean, for example, that every compare instruction would require
a sign- or zero-extension.  Since you assign less than you reference
a variable, it's more efficient to store the variable in the wider more and
make sure the extension is done on every store.

Please explain how this concept is useful for floating-point.