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0b2036cad0
Before this commit, cc-wrapper/default.nix was using `isGccArchSupported` to validate `-mtune=` values. This has two problems: - On x86, `-mtune=` can take the same values as `-march`, plus two additional values `generic` and `intel` which are not valid for `-march`. - On ARM, `-mtune=` does not take the same values as `-march=`; instead it takes the same values as `-mcpu`. This commit fixes these two problems by adding a new `isGccTuneSupported` function. For `isx86` this returns `true` for the two special values and otherwise defers to `isGccArchSupported`. This commit also adds support for `-mtune=` on Aarch64. Unfortunately on Aarch64, Clang does not accept as wide a variety of `-mtune=` values as Gcc does. In particular, Clang does not tune for big.LITTLE mixed-model chips like the very popular RK3399, which is targeted using `-march=cortex-a72.cortex-a53` in gcc. To address this problem, this commit also adds a function `findBestTuneApproximation` which can be used to map clang-unsupported tunings like `cortex-a72.cortex-a53` to less-precise tunings like `cortex-a53`. The work which led to this commit arose because we now have packages, like `crosvm`, which use *both* `clang` *and* `gcc`. Previously I had been using `overrideAttrs` to set `NIX_CFLAGS_COMPILE` on a package-by-package basis based on which compiler that package used. Since we now have packages which use *both* compilers, this strategy no longer works. I briefly considered splitting `NIX_CFLAGS_COMPILE` into `NIX_CFLAGS_COMPILE_GCC` and `NIX_CFLAGS_COMPILE_CLANG`, but since `NIX_CFLAGS_COMPILE` is sort of a hack to begin with I figured that adding the logic to `cc-wrapper` would be preferable. |
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| .. | ||
| add-clang-cc-cflags-before.sh | ||
| add-flags.sh | ||
| add-gnat-extra-flags.sh | ||
| add-hardening.sh | ||
| cc-wrapper.sh | ||
| default.nix | ||
| fortran-hook.sh | ||
| gnat-wrapper.sh | ||
| go-wrapper.sh | ||
| setup-hook.sh | ||