Auto merge of #93577 - nikic:llvm-14, r=nagisa

Upgrade to LLVM 14

LLVM patch state:
 * [x] https://github.com/llvm/llvm-project/commit/a55727f334b39600bfc71144b11b42aae6b94e0b Backported.
 * [x] https://github.com/rust-lang/llvm-project/commit/c3c82dc12402dd41441180c0c6cf7aed7e330c53 Backported as https://github.com/llvm/llvm-project/commit/917c47b3bf0dfc45a2a5ba12c1397d647ecf4017.
 * [x] https://github.com/rust-lang/llvm-project/commit/6e8f9ab632d12271355d10d34c9835a7ba14e4b9 No plan to upstream.
 * [x] https://github.com/llvm/llvm-project/commit/319f4b2d52e31b000db75a0a2484b5f2ab90534a Backported.
 * [x] https://github.com/rust-lang/llvm-project/commit/8b2c25d321f877161f85218479e2d1317d770e18 No plan to upstream.
 * [x] https://github.com/rust-lang/llvm-project/commit/75fef2efd427362c8f16b2d09e6ebf44069e3919 No plan to upstream.
 * [ ] https://github.com/rust-lang/llvm-project/commit/adef757547de5a570d9f6a00d3e6ac16c666ab79 Upstreamed as https://github.com/llvm/llvm-project/commit/2d2ef384b2f6e723edb793d08f52e7f4dc94ba3a. Needs backport.
 * [x] https://github.com/rust-lang/llvm-project/commit/4b7c1b4910e9fa9e04f23f06be078e168ef4c0ee No plan to upstream.
 * [x] https://github.com/rust-lang/llvm-project/commit/3f5ab0c061adb723f25b94243828b6b5407720c8 No plan to upstream.
 * [x] https://github.com/rust-lang/llvm-project/commit/514d05500e0e15e358f05f5c4cec78a805858f8e No plan to upstream.
 * [ ] https://github.com/rust-lang/llvm-project/commit/54c586958564582b3341d1838a5de86541e5fecf Under review at https://reviews.llvm.org/D119695 and https://reviews.llvm.org/D119856.

Release timeline:
 * LLVM 14.0.0 final planned for Mar 15.
 * Rust 1.60.0 planned for Apr 7.

Compile-time:
  * https://perf.rust-lang.org/compare.html?start=250384edc5d78533e993f38c60d64e42b21684b2&end=b87df8d2c7c5d9ac448c585de10927ab2ee1b864
  * A slight improvement on average, though no big changes either way.
  * There are some larger max-rss improvements.

r? `@ghost`

1 files changed, 24 insertions, 16 deletions

diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index 727d079d83d..b1c14c7e44b 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -217,24 +217,32 @@ pub fn check_tied_features(
 
 pub fn target_features(sess: &Session) -> Vec<Symbol> {
     let target_machine = create_informational_target_machine(sess);
-    supported_target_features(sess)
-        .iter()
-        .filter_map(
-            |&(feature, gate)| {
+    let mut features: Vec<Symbol> =
+        supported_target_features(sess)
+            .iter()
+            .filter_map(|&(feature, gate)| {
                 if sess.is_nightly_build() || gate.is_none() { Some(feature) } else { None }
-            },
-        )
-        .filter(|feature| {
-            for llvm_feature in to_llvm_feature(sess, feature) {
-                let cstr = CString::new(llvm_feature).unwrap();
-                if unsafe { llvm::LLVMRustHasFeature(target_machine, cstr.as_ptr()) } {
-                    return true;
+            })
+            .filter(|feature| {
+                for llvm_feature in to_llvm_feature(sess, feature) {
+                    let cstr = CString::new(llvm_feature).unwrap();
+                    if unsafe { llvm::LLVMRustHasFeature(target_machine, cstr.as_ptr()) } {
+                        return true;
+                    }
                 }
-            }
-            false
-        })
-        .map(|feature| Symbol::intern(feature))
-        .collect()
+                false
+            })
+            .map(|feature| Symbol::intern(feature))
+            .collect();
+
+    // LLVM 14 changed the ABI for i128 arguments to __float/__fix builtins on Win64
+    // (see https://reviews.llvm.org/D110413). This unstable target feature is intended for use
+    // by compiler-builtins, to export the builtins with the expected, LLVM-version-dependent ABI.
+    // The target feature can be dropped once we no longer support older LLVM versions.
+    if sess.is_nightly_build() && get_version() >= (14, 0, 0) {
+        features.push(Symbol::intern("llvm14-builtins-abi"));
+    }
+    features
 }
 
 pub fn print_version() {