Shade cloth, old plywood, anything to keep them cool. Yes, you need sun protection for your run. We have old cedar siding on two sides of their night pen and in their new day pen we will have a plywood tent for them to retreat to, with enough room at all times of the day for every hen. Make sure there is water, lots of it, in several locations and especially in the shady spots where the water will stay cool. I've never figured out how to put ice in their waterers without buying a bag of ice, but instead, I change their water in the afternoon and replace it with cooler water.
You can create shade without planting shrubs and trees. Keep giant pots of bamboo and large, leafy shrubs in the run. Keep the black pots shaded with straw or hay and keep them well watered. Put a couple of cherry tomato plants in there too. They love love love tomatoes! Nice and juicy, too. You can feed them cantaloupe and tomatoes, too, to keep them hydrated. Wet down their feed (chickens loooove wet feed. Makes it nice and smelly!) Soak the cracked corn or other grains you give as treats (always a good idea anyhow.) My chickens love soaked split peas I grind up in the food processor. Really protein heavy, though, so use in moderation. Lots of leafy weeds.
It cannot be understated how important water is to chickens during the heat. You will be amazed at how much they go through. Water is far more important than shade, though shade is still very important.
If it gets really hot, do not be surprised if you see a drop in egg laying.