Bug 1756570 - [loong64] Add basic build support for LoongArch64 port. r=glandium

Differential Revision: https://phabricator.services.mozilla.com/D139567

build/moz.configure/init.configure

@@ -526,6 +526,9 @@ def split_triplet(triplet, allow_msvc=False, allow_wasi=False):
     elif cpu in ("riscv64", "riscv64gc"):
         canonical_cpu = "riscv64"
         endianness = "little"
+    elif cpu.startswith("loongarch64"):
+        canonical_cpu = "loongarch64"
+        endianness = "little"
     elif cpu == "sh4":
         canonical_cpu = "sh4"
         endianness = "little"

memory/build/mozjemalloc.cpp

@@ -202,8 +202,9 @@ using namespace mozilla;
 // depending on kernel configuration, so they are opted out by default.
 // Debug builds are opted out too, for test coverage.
 #ifndef MOZ_DEBUG
-#  if !defined(__ia64__) && !defined(__sparc__) && !defined(__mips__) && \
-      !defined(__aarch64__) && !defined(__powerpc__) && !defined(XP_MACOSX)
+#  if !defined(__ia64__) && !defined(__sparc__) && !defined(__mips__) &&       \
+      !defined(__aarch64__) && !defined(__powerpc__) && !defined(XP_MACOSX) && \
+      !defined(__loongarch__)
 #    define MALLOC_STATIC_PAGESIZE 1
 #  endif
 #endif
@@ -471,6 +472,8 @@ static const size_t kChunkSizeMask = kChunkSize - 1;
 // Platform specific page size conditions copied from js/public/HeapAPI.h
 #  if defined(__powerpc64__)
 static const size_t gPageSize = 64_KiB;
+#  elif defined(__loongarch64)
+static const size_t gPageSize = 16_KiB;
 #  else
 static const size_t gPageSize = 4_KiB;
 #  endif

mfbt/tests/TestPoisonArea.cpp

@@ -165,6 +165,9 @@
 #elif defined __aarch64__ || defined _M_ARM64
 #  define RETURN_INSTR 0xd65f03c0 /* ret */
 
+#elif defined __loongarch64
+#  define RETURN_INSTR 0x4c000020 /* jirl zero, ra, 0 */
+
 #elif defined __ia64
 struct ia64_instr {
   uint32_t mI[4];

python/mozbuild/mozbuild/configure/constants.py

@@ -47,6 +47,7 @@ CPU_bitness = {
     "arm": 32,
     "hppa": 32,
     "ia64": 64,
+    "loongarch64": 64,
     "m68k": 32,
     "mips32": 32,
     "mips64": 64,
@@ -95,6 +96,7 @@ CPU_preprocessor_checks = OrderedDict(
         ("mips64", "__mips64"),
         ("mips32", "__mips__"),
         ("riscv64", "__riscv && __riscv_xlen == 64"),
+        ("loongarch64", "__loongarch64"),
         ("sh4", "__sh__"),
         ("wasm32", "__wasm32__"),
     )