Enable tests and compiler-builtins for f16/f128

Author: beetrees

build_system/build_sysroot.rs

@@ -235,7 +235,7 @@ fn build_clif_sysroot_for_triple(
     compiler.rustflags.extend(rustflags);
     let mut build_cmd = STANDARD_LIBRARY.build(&compiler, dirs);
     build_cmd.arg("--release");
-    build_cmd.arg("--features").arg("backtrace panic-unwind compiler-builtins-no-f16-f128");
+    build_cmd.arg("--features").arg("backtrace panic-unwind");
     build_cmd.arg(format!("-Zroot-dir={}", STDLIB_SRC.to_path(dirs).display()));
     build_cmd.env("CARGO_PROFILE_RELEASE_DEBUG", "true");
     build_cmd.env("__CARGO_DEFAULT_LIB_METADATA", "cg_clif");

scripts/setup_rust_fork.sh

@@ -43,7 +43,7 @@ verbose-tests = false
 # disabled bootstrap will crash trying to copy llvm tools for the bootstrap
 # compiler.
 llvm-tools = false
-std-features = ["panic-unwind", "compiler-builtins-no-f16-f128"]
+std-features = ["panic-unwind"]
 
 EOF
 

scripts/test_rustc_tests.sh

@@ -72,14 +72,6 @@ rm tests/ui/consts/precise-drop-with-coverage.rs
 rm tests/ui/issues/issue-85461.rs
 rm -r tests/ui/instrument-coverage/
 
-# missing f16/f128 support
-rm tests/ui/half-open-range-patterns/half-open-range-pats-semantics.rs
-rm tests/ui/asm/aarch64/type-f16.rs
-rm tests/ui/float/conv-bits-runtime-const.rs
-rm tests/ui/consts/const-eval/float_methods.rs
-rm tests/ui/match/match-float.rs
-rm tests/ui/float/target-has-reliable-nightly-float.rs
-
 # optimization tests
 # ==================
 rm tests/ui/codegen/issue-28950.rs # depends on stack size optimizations

src/lib.rs

@@ -201,14 +201,36 @@ impl CodegenBackend for CraneliftCodegenBackend {
         // FIXME do `unstable_target_features` properly
         let unstable_target_features = target_features.clone();
 
+        // FIXME(f16_f128): LLVM 20 (currently used by `rustc`) passes `f128` in XMM registers on
+        // Windows, whereas LLVM 21+ and Cranelift pass it indirectly. This means that `f128` won't
+        // work when linking against a LLVM-built sysroot.
+        let has_reliable_f128 = !sess.target.is_like_windows;
+        let has_reliable_f16 = match &*sess.target.arch {
+            // FIXME(f16_f128): LLVM 20 does not support `f16` on s390x, meaning the required
+            // builtins are not available in `compiler-builtins`.
+            "s390x" => false,
+            // FIXME(f16_f128): `rustc_codegen_llvm` currently disables support on Windows GNU
+            // targets due to GCC using a different ABI than LLVM. Therefore `f16` won't be
+            // available when using a LLVM-built sysroot.
+            "x86_64"
+                if sess.target.os == "windows"
+                    && sess.target.env == "gnu"
+                    && sess.target.abi != "llvm" =>
+            {
+                false
+            }
+            _ => true,
+        };
+
         TargetConfig {
             target_features,
             unstable_target_features,
-            // Cranelift does not yet support f16 or f128
-            has_reliable_f16: false,
-            has_reliable_f16_math: false,
-            has_reliable_f128: false,
-            has_reliable_f128_math: false,
+            // `rustc_codegen_cranelift` polyfills functionality not yet
+            // available in Cranelift.
+            has_reliable_f16,
+            has_reliable_f16_math: has_reliable_f16,
+            has_reliable_f128,
+            has_reliable_f128_math: has_reliable_f128,
         }
     }