6 files changed, 43 insertions, 13 deletions
diff --git a/src/bootstrap/defaults/bootstrap.dist.toml b/src/bootstrap/defaults/bootstrap.dist.toml
index 9daf9faac14..b111a20f8d8 100644
--- a/src/bootstrap/defaults/bootstrap.dist.toml
+++ b/src/bootstrap/defaults/bootstrap.dist.toml
@@ -14,6 +14,10 @@ compiletest-use-stage0-libtest = false
 [llvm]
 download-ci-llvm = false
 
+# Most users installing from source want to build all parts of the project from source.
+[gcc]
+download-ci-gcc = false
+
 [rust]
 # We have several defaults in bootstrap that depend on whether the channel is `dev` (e.g. `omit-git-hash` and `download-ci-llvm`).
 # Make sure they don't get set when installing from source.
diff --git a/src/bootstrap/src/core/build_steps/compile.rs b/src/bootstrap/src/core/build_steps/compile.rs
index 0b75e85772f..1458b0beefa 100644
--- a/src/bootstrap/src/core/build_steps/compile.rs
+++ b/src/bootstrap/src/core/build_steps/compile.rs
@@ -1383,14 +1383,17 @@ pub fn rustc_cargo_env(builder: &Builder<'_>, cargo: &mut Cargo, target: TargetS
         }
     }
 
-    // Build jemalloc on AArch64 with support for page sizes up to 64K
-    // See: https://github.com/rust-lang/rust/pull/135081
     // See also the "JEMALLOC_SYS_WITH_LG_PAGE" setting in the tool build step.
-    if builder.config.jemalloc(target)
-        && target.starts_with("aarch64")
-        && env::var_os("JEMALLOC_SYS_WITH_LG_PAGE").is_none()
-    {
-        cargo.env("JEMALLOC_SYS_WITH_LG_PAGE", "16");
+    if builder.config.jemalloc(target) && env::var_os("JEMALLOC_SYS_WITH_LG_PAGE").is_none() {
+        // Build jemalloc on AArch64 with support for page sizes up to 64K
+        // See: https://github.com/rust-lang/rust/pull/135081
+        if target.starts_with("aarch64") {
+            cargo.env("JEMALLOC_SYS_WITH_LG_PAGE", "16");
+        }
+        // Build jemalloc on LoongArch with support for page sizes up to 16K
+        else if target.starts_with("loongarch") {
+            cargo.env("JEMALLOC_SYS_WITH_LG_PAGE", "14");
+        }
     }
 }
 
diff --git a/src/bootstrap/src/core/build_steps/gcc.rs b/src/bootstrap/src/core/build_steps/gcc.rs
index 77c9622a9bf..717dea37e9e 100644
--- a/src/bootstrap/src/core/build_steps/gcc.rs
+++ b/src/bootstrap/src/core/build_steps/gcc.rs
@@ -32,6 +32,10 @@ pub struct GccOutput {
 impl GccOutput {
     /// Install the required libgccjit library file(s) to the specified `path`.
     pub fn install_to(&self, builder: &Builder<'_>, directory: &Path) {
+        if builder.config.dry_run() {
+            return;
+        }
+
         // At build time, cg_gcc has to link to libgccjit.so (the unversioned symbol).
         // However, at runtime, it will by default look for libgccjit.so.0.
         // So when we install the built libgccjit.so file to the target `directory`, we add it there
@@ -39,8 +43,16 @@ impl GccOutput {
         let mut target_filename = self.libgccjit.file_name().unwrap().to_str().unwrap().to_string();
         target_filename.push_str(".0");
 
+        // If we build libgccjit ourselves, then `self.libgccjit` can actually be a symlink.
+        // In that case, we have to resolve it first, otherwise we'd create a symlink to a symlink,
+        // which wouldn't work.
+        let actual_libgccjit_path = t!(
+            self.libgccjit.canonicalize(),
+            format!("Cannot find libgccjit at {}", self.libgccjit.display())
+        );
+
         let dst = directory.join(target_filename);
-        builder.copy_link(&self.libgccjit, &dst, FileType::NativeLibrary);
+        builder.copy_link(&actual_libgccjit_path, &dst, FileType::NativeLibrary);
     }
 }
 
diff --git a/src/bootstrap/src/core/build_steps/tool.rs b/src/bootstrap/src/core/build_steps/tool.rs
index 6870bf3eddc..dcc4898cae1 100644
--- a/src/bootstrap/src/core/build_steps/tool.rs
+++ b/src/bootstrap/src/core/build_steps/tool.rs
@@ -228,12 +228,18 @@ pub fn prepare_tool_cargo(
     // own copy
     cargo.env("LZMA_API_STATIC", "1");
 
-    // Build jemalloc on AArch64 with support for page sizes up to 64K
-    // See: https://github.com/rust-lang/rust/pull/135081
     // Note that `miri` always uses jemalloc. As such, there is no checking of the jemalloc build flag.
     // See also the "JEMALLOC_SYS_WITH_LG_PAGE" setting in the compile build step.
-    if target.starts_with("aarch64") && env::var_os("JEMALLOC_SYS_WITH_LG_PAGE").is_none() {
-        cargo.env("JEMALLOC_SYS_WITH_LG_PAGE", "16");
+    if env::var_os("JEMALLOC_SYS_WITH_LG_PAGE").is_none() {
+        // Build jemalloc on AArch64 with support for page sizes up to 64K
+        // See: https://github.com/rust-lang/rust/pull/135081
+        if target.starts_with("aarch64") {
+            cargo.env("JEMALLOC_SYS_WITH_LG_PAGE", "16");
+        }
+        // Build jemalloc on LoongArch with support for page sizes up to 16K
+        else if target.starts_with("loongarch") {
+            cargo.env("JEMALLOC_SYS_WITH_LG_PAGE", "14");
+        }
     }
 
     // CFG_RELEASE is needed by rustfmt (and possibly other tools) which
diff --git a/src/bootstrap/src/core/config/mod.rs b/src/bootstrap/src/core/config/mod.rs
index 5999348a7fe..05a5dfc0bc5 100644
--- a/src/bootstrap/src/core/config/mod.rs
+++ b/src/bootstrap/src/core/config/mod.rs
@@ -422,10 +422,10 @@ impl std::str::FromStr for RustcLto {
 #[derive(Default, Clone)]
 pub enum GccCiMode {
     /// Build GCC from the local `src/gcc` submodule.
-    #[default]
     BuildLocally,
     /// Try to download GCC from CI.
     /// If it is not available on CI, it will be built locally instead.
+    #[default]
     DownloadFromCi,
 }
 
diff --git a/src/bootstrap/src/utils/change_tracker.rs b/src/bootstrap/src/utils/change_tracker.rs
index 01309072927..03b39882e30 100644
--- a/src/bootstrap/src/utils/change_tracker.rs
+++ b/src/bootstrap/src/utils/change_tracker.rs
@@ -541,4 +541,9 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
         severity: ChangeSeverity::Info,
         summary: "Added a new option `rust.break-on-ice` to control if internal compiler errors cause a debug break on Windows.",
     },
+    ChangeInfo {
+        change_id: 146435,
+        severity: ChangeSeverity::Info,
+        summary: "The default value of the `gcc.download-ci-gcc` option has been changed to `true`.",
+    },
 ];