Use more accurate ELF flags on MIPS

compiler/rustc_target/src/spec/mod.rs

@@ -3567,7 +3567,14 @@ impl Target {
             "x86" => (Architecture::I386, None),
             "s390x" => (Architecture::S390x, None),
             "mips" | "mips32r6" => (Architecture::Mips, None),
-            "mips64" | "mips64r6" => (Architecture::Mips64, None),
+            "mips64" | "mips64r6" => (
+                if self.options.llvm_abiname.as_ref() == "n32" {
+                    Architecture::Mips64_N32
+                } else {
+                    Architecture::Mips64
+                },
+                None,
+            ),
             "x86_64" => (
                 if self.pointer_width == 32 {
                     Architecture::X86_64_X32

compiler/rustc_target/src/spec/targets/mips64_openwrt_linux_musl.rs

@@ -27,6 +27,7 @@ pub(crate) fn target() -> Target {
             abi: "abi64".into(),
             endian: Endian::Big,
             mcount: "_mcount".into(),
+            llvm_abiname: "n64".into(),
             ..base
         },
     }

compiler/rustc_target/src/spec/targets/mips64_unknown_linux_gnuabi64.rs

@@ -22,6 +22,7 @@ pub(crate) fn target() -> Target {
             features: "+mips64r2,+xgot".into(),
             max_atomic_width: Some(64),
             mcount: "_mcount".into(),
+            llvm_abiname: "n64".into(),
 
             ..base::linux_gnu::opts()
         },

compiler/rustc_target/src/spec/targets/mips64_unknown_linux_muslabi64.rs

@@ -25,6 +25,7 @@ pub(crate) fn target() -> Target {
             mcount: "_mcount".into(),
             // FIXME(compiler-team#422): musl targets should be dynamically linked by default.
             crt_static_default: true,
+            llvm_abiname: "n64".into(),
             ..base
         },
     }

compiler/rustc_target/src/spec/targets/mips64el_unknown_linux_gnuabi64.rs

@@ -19,6 +19,7 @@ pub(crate) fn target() -> Target {
             features: "+mips64r2,+xgot".into(),
             max_atomic_width: Some(64),
             mcount: "_mcount".into(),
+            llvm_abiname: "n64".into(),
 
             ..base::linux_gnu::opts()
         },

compiler/rustc_target/src/spec/targets/mips64el_unknown_linux_muslabi64.rs

@@ -19,6 +19,11 @@ pub(crate) fn target() -> Target {
         pointer_width: 64,
         data_layout: "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128".into(),
         arch: "mips64".into(),
-        options: TargetOptions { abi: "abi64".into(), mcount: "_mcount".into(), ..base },
+        options: TargetOptions {
+            abi: "abi64".into(),
+            mcount: "_mcount".into(),
+            llvm_abiname: "n64".into(),
+            ..base
+        },
     }
 }

compiler/rustc_target/src/spec/targets/mipsisa64r6_unknown_linux_gnuabi64.rs

@@ -22,6 +22,7 @@ pub(crate) fn target() -> Target {
             features: "+mips64r6".into(),
             max_atomic_width: Some(64),
             mcount: "_mcount".into(),
+            llvm_abiname: "n64".into(),
 
             ..base::linux_gnu::opts()
         },

compiler/rustc_target/src/spec/targets/mipsisa64r6el_unknown_linux_gnuabi64.rs

@@ -19,6 +19,7 @@ pub(crate) fn target() -> Target {
             features: "+mips64r6".into(),
             max_atomic_width: Some(64),
             mcount: "_mcount".into(),
+            llvm_abiname: "n64".into(),
 
             ..base::linux_gnu::opts()
         },