Apple devices in 2018
Both iPhone and Watch ship with a Secure Enclave processor. Both are also H11-class SoCs. As such, there are broad similarities between the different blocks. Embedded cores present on-die use firmware written with RTKit, which is Apple's own broadly-used RTOS on cores codenamed Chinook. The codename for the eSIM platform on both the iPhone and Watch is Vinyl. The NFC (+Apple Pay?) controller is named Stockholm, and the Apple Watch Series 4 + iPhone Xs and Xr ship with version 5.
TSMC is the foundry used exclusively for all the new SoCs this year, using their 7nm mobile process.
Apple Watch Series 4 (S4: T8006) uses two Tempest cores as the AP. The ILP32 ARMv8 ABI is used, making possible to use ARMv8 instructions with lower memory pressure. The GPU is Apple G11M. The arm64_32 ABI is used, to be able to recompile LLVM bitcode from older Watches to S4 without action from the developer. On cellular modem-equipped variants, Intel's IBIS modem is used, which isn't referenced anywhere publicly, except a post on thelayoff. It runs on an Arm core. The neural engine is codenamed Mercury.
Apple M9 is the WiFi and Bluetooth controller, codenamed Marconi. The WiFi PHY has the Tesla codename. The firmware is ran on ARM Cortex-R5 cores with software floating-point.
Apple A12 (T8020) uses two Vortex and four Tempest cores as the AP. The arm64e ABI is used, which adds support for pointer authentication. The video engine has the Panda codename. The GPU is Apple G11P.
Intel's ICE baseband is used (XMM7560, flashless configuration), which has a pair of Intel Atom cores at 1.2GHz (?).
The neural engine is codenamed Quin and the ISP is named Petra. A Lattice FPGA driving a small block called Maggie is present.
iPad Pro 2018 uses the Apple A12X (T8027), which has 4 big cores and 4 little cores. The neural engine is named Pontus. Maggie is not present. The GPU is Apple G11G.
https://www.thelayoff.com/t/LUMrIcz An employee rant, but unfortunately the only place where the IBIS modem is referenced anywhere on the public Internet.
https://twitter.com/esizkur/status/1040899693524516864 on VMX being present but unused apart from a switch to VMX non-root at bootup.