llvmPackages_{12,13,14,15,16,17,18}.compiler-rt: fix build with clang 18

[reckenrode]

Description of changes

Clang 18 rejects assembly code that used to be accepted because it can cause runtime crashes. This change prevents older versions of compiler-rt from building on Darwin with a clang 18 stdenv.

The fix is to apply or backport llvm/llvm-project@7939ce3.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[paparodeo]

since the llvm versions were unified this PR needs a little update. The diff below should work (tested with llvm13) and dropped llvm_12 given it is currently broken on darwin but the patch can be added back. I can open a new PR if necessary.

updated compiler-rt diff

diff --git a/pkgs/development/compilers/llvm/common/default.nix b/pkgs/development/compilers/llvm/common/default.nix
index c3a98c1f063f..26b3a7977893 100644
--- a/pkgs/development/compilers/llvm/common/default.nix
+++ b/pkgs/development/compilers/llvm/common/default.nix
@@ -990,6 +990,14 @@ let
         ++ lib.optional (
           lib.versionAtLeast metadata.release_version "14" && lib.versionOlder metadata.release_version "18"
         ) (metadata.getVersionFile "compiler-rt/gnu-install-dirs.patch")
+        ++ lib.optional (
+          lib.versionAtLeast metadata.release_version "13" && lib.versionOlder metadata.release_version "18"
+          ) (fetchpatch {
+              name = "cfi_startproc-after-label.patch";
+              url = "https://github.com/llvm/llvm-project/commit/7939ce39dac0078fef7183d6198598b99c652c88.patch";
+              stripLen = 1;
+              hash = "sha256-tGqXsYvUllFrPa/r/dsKVlwx5IrcJGccuR1WAtUg7/o=";
+        })
         ++ [
           # ld-wrapper dislikes `-rpath-link //nix/store`, so we normalize away the
           # extra `/`.

[emilazy]

Fixed on the LLVM 19 branch in #354569. Could be backported if anyone cares.