Rollup merge of #60981 - alexcrichton:update-compiler-builtins, r=cuviper

Bump compiler-builtins to 0.1.15

This commit bumps the `compiler-builtins` dependency to 0.1.15 which
expects to have the source for `compiler-rt` provided externally if the
`c` feature is enabled. This then plumbs through the necessary support
in the build system to ensure that if the `llvm-project` directory is
checked out and present that we enable the `c` feature of
`compiler-builtins` and compile in all the C intrinsics.

5 files changed, 35 insertions, 10 deletions

diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs
index e1cdd226fd6..2da5e1c5902 100644
--- a/src/bootstrap/compile.rs
+++ b/src/bootstrap/compile.rs
@@ -161,7 +161,33 @@ pub fn std_cargo(builder: &Builder<'_>,
         cargo.env("MACOSX_DEPLOYMENT_TARGET", target);
     }
 
+    // Determine if we're going to compile in optimized C intrinsics to
+    // the `compiler-builtins` crate. These intrinsics live in LLVM's
+    // `compiler-rt` repository, but our `src/llvm-project` submodule isn't
+    // always checked out, so we need to conditionally look for this. (e.g. if
+    // an external LLVM is used we skip the LLVM submodule checkout).
+    //
+    // Note that this shouldn't affect the correctness of `compiler-builtins`,
+    // but only its speed. Some intrinsics in C haven't been translated to Rust
+    // yet but that's pretty rare. Other intrinsics have optimized
+    // implementations in C which have only had slower versions ported to Rust,
+    // so we favor the C version where we can, but it's not critical.
+    //
+    // If `compiler-rt` is available ensure that the `c` feature of the
+    // `compiler-builtins` crate is enabled and it's configured to learn where
+    // `compiler-rt` is located.
+    let compiler_builtins_root = builder.src.join("src/llvm-project/compiler-rt");
+    let compiler_builtins_c_feature = if compiler_builtins_root.exists() {
+        cargo.env("RUST_COMPILER_RT_ROOT", &compiler_builtins_root);
+        " compiler-builtins-c".to_string()
+    } else {
+        String::new()
+    };
+
     if builder.no_std(target) == Some(true) {
+        let mut features = "compiler-builtins-mem".to_string();
+        features.push_str(&compiler_builtins_c_feature);
+
         // for no-std targets we only compile a few no_std crates
         cargo
             .args(&["-p", "alloc"])
@@ -170,7 +196,8 @@ pub fn std_cargo(builder: &Builder<'_>,
             .arg("--features")
             .arg("compiler-builtins-mem compiler-builtins-c");
     } else {
-        let features = builder.std_features();
+        let mut features = builder.std_features();
+        features.push_str(&compiler_builtins_c_feature);
 
         if compiler.stage != 0 && builder.config.sanitizers {
             // This variable is used by the sanitizer runtime crates, e.g.
diff --git a/src/build_helper/lib.rs b/src/build_helper/lib.rs
index 60911d91789..8b00c1d81b0 100644
--- a/src/build_helper/lib.rs
+++ b/src/build_helper/lib.rs
@@ -288,9 +288,9 @@ pub fn sanitizer_lib_boilerplate(sanitizer_name: &str)
     } else {
         format!("static={}", link_name)
     };
-    // The source for `compiler-rt` comes from the `compiler-builtins` crate, so
-    // load our env var set by cargo to find the source code.
-    let dir = env::var_os("DEP_COMPILER_RT_COMPILER_RT").unwrap();
+    // This env var is provided by rustbuild to tell us where `compiler-rt`
+    // lives.
+    let dir = env::var_os("RUST_COMPILER_RT_ROOT").unwrap();
     let lib = native_lib_boilerplate(
         dir.as_ref(),
         sanitizer_name,
diff --git a/src/libprofiler_builtins/build.rs b/src/libprofiler_builtins/build.rs
index 331edb73d6d..491986480de 100644
--- a/src/libprofiler_builtins/build.rs
+++ b/src/libprofiler_builtins/build.rs
@@ -57,9 +57,7 @@ fn main() {
         cfg.define("COMPILER_RT_HAS_ATOMICS", Some("1"));
     }
 
-    // The source for `compiler-rt` comes from the `compiler-builtins` crate, so
-    // load our env var set by cargo to find the source code.
-    let root = env::var_os("DEP_COMPILER_RT_COMPILER_RT").unwrap();
+    let root = env::var_os("RUST_COMPILER_RT_ROOT").unwrap();
     let root = Path::new(&root);
 
     for src in profile_sources {
diff --git a/src/libstd/Cargo.toml b/src/libstd/Cargo.toml
index 55e8b39974e..c4c1170e539 100644
--- a/src/libstd/Cargo.toml
+++ b/src/libstd/Cargo.toml
@@ -19,7 +19,7 @@ panic_unwind = { path = "../libpanic_unwind", optional = true }
 panic_abort = { path = "../libpanic_abort" }
 core = { path = "../libcore" }
 libc = { version = "0.2.51", default-features = false, features = ['rustc-dep-of-std'] }
-compiler_builtins = { version = "0.1.14" }
+compiler_builtins = { version = "0.1.15" }
 profiler_builtins = { path = "../libprofiler_builtins", optional = true }
 unwind = { path = "../libunwind" }
 hashbrown = { version = "0.3.0", features = ['rustc-dep-of-std'] }
@@ -49,12 +49,12 @@ fortanix-sgx-abi = { version = "0.3.2", features = ['rustc-dep-of-std'] }
 cc = "1.0"
 
 [features]
-default = ["compiler_builtins_c", "std_detect_file_io", "std_detect_dlsym_getauxval"]
+default = ["std_detect_file_io", "std_detect_dlsym_getauxval"]
 
 backtrace = ["backtrace-sys"]
 panic-unwind = ["panic_unwind"]
 profiler = ["profiler_builtins"]
-compiler_builtins_c = ["alloc/compiler-builtins-c"]
+compiler-builtins-c = ["alloc/compiler-builtins-c"]
 llvm-libunwind = ["unwind/llvm-libunwind"]
 
 # Make panics and failed asserts immediately abort without formatting any message
diff --git a/src/llvm-project b/src/llvm-project
-Subproject 2c5656ae593851d0b2336a727cc14b77a06b8ac
+Subproject 4efebe31651d5520bcba968878dbb8a4971d204