Test that the compiler/library builds with -Zmir-opt-level=3 -Zvalidate-mir

config.toml.example

@@ -666,6 +666,9 @@ changelog-seen = 2
 # LTO entirely.
 #lto = "thin-local"
 
+# Build compiler with the optimization enabled and -Zvalidate-mir, currently only for `std`
+#validate-mir-opts = 3
+
 # =============================================================================
 # Options for specific targets
 #

src/bootstrap/builder.rs

@@ -1915,6 +1915,13 @@ impl<'a> Builder<'a> {
             }
         }
 
+        if matches!(mode, Mode::Std) {
+            if let Some(mir_opt_level) = self.config.rust_validate_mir_opts {
+                rustflags.arg("-Zvalidate-mir");
+                rustflags.arg(&format!("-Zmir-opt-level={}", mir_opt_level));
+            }
+        }
+
         Cargo { command: cargo, rustflags, rustdocflags, allow_features }
     }
 

src/bootstrap/config.rs

@@ -173,6 +173,7 @@ pub struct Config {
     pub rust_profile_use: Option<String>,
     pub rust_profile_generate: Option<String>,
     pub rust_lto: RustcLto,
+    pub rust_validate_mir_opts: Option<u32>,
     pub llvm_profile_use: Option<String>,
     pub llvm_profile_generate: bool,
     pub llvm_libunwind_default: Option<LlvmLibunwind>,
@@ -770,6 +771,7 @@ define_config! {
         // ignored; this is set from an env var set by bootstrap.py
         download_rustc: Option<StringOrBool> = "download-rustc",
         lto: Option<String> = "lto",
+        validate_mir_opts: Option<u32> = "validate-mir-opts",
     }
 }
 
@@ -1149,6 +1151,7 @@ impl Config {
                 .as_deref()
                 .map(|value| RustcLto::from_str(value).unwrap())
                 .unwrap_or_default();
+            config.rust_validate_mir_opts = rust.validate_mir_opts;
         } else {
             config.rust_profile_use = flags.rust_profile_use;
             config.rust_profile_generate = flags.rust_profile_generate;

src/ci/run.sh

@@ -58,6 +58,7 @@ RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --disable-manage-submodules"
 RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --enable-locked-deps"
 RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --enable-cargo-native-static"
 RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set rust.codegen-units-std=1"
+RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set rust.validate-mir-opts=3"
 
 # Only produce xz tarballs on CI. gz tarballs will be generated by the release
 # process by recompressing the existing xz ones. This decreases the storage