Re: [patch, tree-ssa] PR54295 Incorrect value extension in widening multiply-accumulate

[Andrew Stubbs <ams at codesourcery dot com>]

On 17/08/12 18:05, Richard Earnshaw wrote:
> Take two.
>
> This version should address your concerns about handling
>
> 	(u32)u16 * (u32)u16 -> u64
>
> We now look at each operand directly, but when doing so we check whether
> the operand is the same size as the result or not.  When it is, we can
> strip any conversion; when it isn't the conversion must preserve
> signedness of the inner operand and mustn't be a narrowing conversion.

So, if I understand correctly, this simply prevents it from stripping 
any conversions from the multiply's right-hand-side if they are not 
widening conversions?

That seems fine to me. Not that I have authority to approve it, of course.

Andrew