[Patch, i386] Add minus to list of promotable operators

Currently gcc will promote from QI/HI mode to SI mode various operators but not minus. It will however promote a neg followed by an add (add is in the current list of promotable operators and neg is promoted around config/i386/i386.md:16904). This omission can cause RAT stalls in tight loops.

Re: [Patch, i386] Add minus to list of promotable operators

Hello! Currently gcc will promote from QI/HI mode to SI mode various operators but not minus. It will however promote a neg followed by an add (add is in the current list of promotable operators and neg is promoted around config/i386/i386.md:16904). This omission can cause RAT stalls in