loongarch: various architecture specific fixes (#20912)

lib/std/mem.zig

@@ -17,6 +17,14 @@ pub const page_size = switch (builtin.cpu.arch) {
         else => 4 * 1024,
     },
     .sparc64 => 8 * 1024,
+    .loongarch32, .loongarch64 => switch (builtin.os.tag) {
+        // Linux default KConfig value is 16KiB
+        .linux => 16 * 1024,
+        // FIXME:
+        // There is no other OS supported yet. Use the same value
+        // as Linux for now.
+        else => 16 * 1024,
+    },
     else => 4 * 1024,
 };
 

lib/std/os/linux.zig

@@ -132,6 +132,7 @@ pub const SYS = switch (@import("builtin").cpu.arch) {
     .riscv64 => syscalls.RiscV64,
     .sparc => syscalls.Sparc,
     .sparc64 => syscalls.Sparc64,
+    .loongarch64 => syscalls.LoongArch64,
     .m68k => syscalls.M68k,
     .mips, .mipsel => syscalls.MipsO32,
     .mips64, .mips64el => if (builtin.abi == .gnuabin32)

src/glibc.zig

@@ -1182,6 +1182,7 @@ fn buildSharedLib(
 pub fn needsCrtiCrtn(target: std.Target) bool {
     return switch (target.cpu.arch) {
         .riscv32, .riscv64 => false,
+        .loongarch64 => false,
         else => true,
     };
 }

src/musl.zig

@@ -293,7 +293,8 @@ pub fn needsCrtiCrtn(target: std.Target) bool {
     return switch (target.cpu.arch) {
         .riscv32,
         .riscv64,
-        .wasm32, .wasm64 => return false,
+        .wasm32, .wasm64 => false,
+        .loongarch64 => false,
         else => true,
     };
     // zig fmt: on