Re: [PATCH] Fix expand_binop (PR middle-end/88032)

[Jeff Law <law at redhat dot com>]

On 11/16/18 1:49 AM, Jakub Jelinek wrote:
> Hi!
> 
> On Wed, Nov 14, 2018 at 09:35:30AM -0700, Jeff Law wrote:
>> +	* optabs.c (expand_binop): Pass INT_MODE to operand_subword_force
>> +	iff the operand is a constant.
> 
> This broke gcc.target/i386/pr80173.c testcase.  The problem is
> that while operand_subword handles VOIDmode last argument just fine
> by using GET_MODE (op), so it is only important to use non-VOIDmode if
> op has VOIDmode.  But, operand_subword_force actually has a different
> behavior, if mode is VOIDmode (or BLKmode), it acts just as operand_subword
> followed by assertion that it succeeded, rather than by trying to deal with
> failed operand_subword by forcing it into a pseudo.
> 
> In the testcase, op is a hard register, on which operand_subword fails, but
> if it is forced into pseudo, it succeeds.
> 
> The following patch arranges it by never passing VOIDmode to
> operand_subword_force, pass int_mode as previously if opN has VOIDmode, but
> instead of passing VOIDmode otherwise pass the actual mode of the opN
> operand.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> 
> 2018-11-16  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR middle-end/88032
> 	* optabs.c (expand_binop): For op0_mode use GET_MODE (op0), unless it
> 	is VOIDmode, in which case use int_mode.  Similarly for op1_mode.
Yea, that's fine too -- I had this variant in my tree until the last
cycle of testing where I changed it to VOIDmode :-)  Sorry for the breakage.

jeff