`-mcpu` is a deprecated "alias" (unsupported) on x86 targets for
`-mtune`. Unlike `-mcpu`, `-mtune` simply tunes the code for the CPU but
does not prevent execution on other targets. In order to match the
behaviour of `-mcpu` on ARM, we must use both `-march=` and `-mtune=`.
Adjust this behaviour to allow tuning of code for non-Darwin targets.
- Add frontend and standard library build support for tvOS.
- Add frontend support for watchOS.
watchOS standard library builds are still disabled during SDK bring-up.
To build for TVOS, specify --tvos to build-script.
To build for watchOS, specify --watchos to build-script (not yet supported).
This patch does not include turning on full tests for TVOS or watchOS, and
will be included in a follow-up patch.
Swift SVN r26278
Previously we hardcoded a few important default CPUs, ABIs, and features into
Swift's driver, duplicating work in Clang. Now that we're using Clang's
driver to create the Clang "sub-compiler", we can delegate this work to Clang.
As part of this, I've dropped the options for -target-abi (which was a
frontend-only option anyway) and -target-feature (which was a hidden driver
option and is a frontend-only option in /Clang/). We can revisit this later
if it becomes interesting. I left in -target-cpu, which is now mapped
directly to Clang's -mcpu=.
Swift SVN r22449
