Auto merge of #112374 - chenx97:better-mips64r6, r=jackh726

add mips64r6 and mips32r6 as target_arch values

This PR introduces `"mips32r6"` and `"mips64r6"` as valid `target_arch` values, and would be the arch value used by Tier-3 targets `mipsisa32r6-unknown-linux-gnu`, `mipsisa32r6el-unknown-linux-gnu`, `mipsisa64r6-unknown-linux-gnuabi64` and `mipsisa64r6el-unknown-linux-gnuabi64`.

This PR was inspired by `rustix` attempting to link traditional mips64el objects with mips64r6el objects when building for mips64r6, even though `rustix` recently removed outline assembly support. This is because currently this target's `target_arch` is `"mips64"` and rustix has its respective assembly implementation as well as a pre-compiled little-endian static library prepared for mips64el, a tier-2 target with the same `target_arch`. After some [discussions on zulip](https://rust-lang.zulipchat.com/#narrow/stream/233931-t-compiler.2Fmajor-changes/topic/Add.20New.20Values.20To.20MIPS_ALLOWED_FEATURES.20compiler-team.23595), I decided to treat mips64r6 as an independent architecture from Rust's POV, since these two architectures are incompatible anyway.

This PR is now waiting for `libc` to release a new version with [support](https://github.com/rust-lang/libc/pull/3268) for these `target_arch` values. It is not expected to introduce changes to any other target, especially Tier-1 and Tier-2 targets.

This PR has its corresponding [MCP](https://github.com/rust-lang/compiler-team/issues/632) approved.

3 files changed, 11 insertions, 3 deletions

diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index de43a401926..059eb9ffc7b 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -133,7 +133,12 @@ const EXTRA_CHECK_CFGS: &[(Option<Mode>, &'static str, Option<&[&'static str]>)]
     /* Extra values not defined in the built-in targets yet, but used in std */
     (Some(Mode::Std), "target_env", Some(&["libnx"])),
     // (Some(Mode::Std), "target_os", Some(&[])),
-    (Some(Mode::Std), "target_arch", Some(&["asmjs", "spirv", "nvptx", "xtensa"])),
+    // #[cfg(bootstrap)] mips32r6, mips64r6
+    (
+        Some(Mode::Std),
+        "target_arch",
+        Some(&["asmjs", "spirv", "nvptx", "xtensa", "mips32r6", "mips64r6"]),
+    ),
     /* Extra names used by dependencies */
     // FIXME: Used by serde_json, but we should not be triggering on external dependencies.
     (Some(Mode::Rustc), "no_btreemap_remove_entry", None),
diff --git a/src/librustdoc/clean/cfg.rs b/src/librustdoc/clean/cfg.rs
index 5177cffe6ba..83886dd42aa 100644
--- a/src/librustdoc/clean/cfg.rs
+++ b/src/librustdoc/clean/cfg.rs
@@ -520,7 +520,9 @@ impl<'a> fmt::Display for Display<'a> {
                         "loongarch64" => "LoongArch LA64",
                         "m68k" => "M68k",
                         "mips" => "MIPS",
+                        "mips32r6" => "MIPS Release 6",
                         "mips64" => "MIPS-64",
+                        "mips64r6" => "MIPS-64 Release 6",
                         "msp430" => "MSP430",
                         "powerpc" => "PowerPC",
                         "powerpc64" => "PowerPC-64",
diff --git a/src/tools/miri/src/shims/foreign_items.rs b/src/tools/miri/src/shims/foreign_items.rs
index 6915c396d61..72a4adba8d4 100644
--- a/src/tools/miri/src/shims/foreign_items.rs
+++ b/src/tools/miri/src/shims/foreign_items.rs
@@ -45,8 +45,9 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
         // List taken from `library/std/src/sys/common/alloc.rs`.
         // This list should be kept in sync with the one from libstd.
         let min_align = match this.tcx.sess.target.arch.as_ref() {
-            "x86" | "arm" | "mips" | "powerpc" | "powerpc64" | "asmjs" | "wasm32" => 8,
-            "x86_64" | "aarch64" | "mips64" | "s390x" | "sparc64" | "loongarch64" => 16,
+            "x86" | "arm" | "mips" | "mips32r6" | "powerpc" | "powerpc64" | "asmjs" | "wasm32" => 8,
+            "x86_64" | "aarch64" | "mips64" | "mips64r6" | "s390x" | "sparc64" | "loongarch64" =>
+                16,
             arch => bug!("unsupported target architecture for malloc: `{}`", arch),
         };
         // Windows always aligns, even small allocations.