2 files changed, 21 insertions, 1 deletions

diff --git a/src/lib_jit.c b/src/lib_jit.c
index 05a79d51..7d5e0aef 100644
--- a/src/lib_jit.c
+++ b/src/lib_jit.c
@@ -615,7 +615,21 @@ static uint32_t jit_cpudetect(lua_State *L)
 #elif LJ_TARGET_PPC || LJ_TARGET_PPCSPE
   /* Nothing to do. */
 #elif LJ_TARGET_MIPS
-  /* NYI */
+#if LJ_HASJIT
+  /* Compile-time MIPS CPU detection. */
+#if _MIPS_ARCH_MIPS32R2
+  flags |= JIT_F_MIPS32R2;
+#endif
+  /* Runtime MIPS CPU detection. */
+#if defined(__GNUC__)
+  if (!(flags & JIT_F_MIPS32R2)) {
+    int x;
+    /* On MIPS32R1 rotr is treated as srl. rotr r2,r2,1 -> srl r2,r2,1. */
+    __asm__("li $2, 1\n\t.long 0x00221042\n\tmove %0, $2" : "=r"(x) : : "$2");
+    if (x) flags |= JIT_F_MIPS32R2;  /* Either 0x80000000 (R2) or 0 (R1). */
+  }
+#endif
+#endif
 #else
 #error "Missing CPU detection for this architecture"
 #endif
diff --git a/src/lj_jit.h b/src/lj_jit.h
index 1033e792..dd0c08d8 100644
--- a/src/lj_jit.h
+++ b/src/lj_jit.h
@@ -34,6 +34,12 @@
 /* Names for the CPU-specific flags. Must match the order above. */
 #define JIT_F_CPU_FIRST         JIT_F_ARMV6
 #define JIT_F_CPUSTRING         "\5ARMv6\7ARMv6T2\5ARMv7"
+#elif LJ_TARGET_MIPS
+#define JIT_F_MIPS32R2          0x00000010
+
+/* Names for the CPU-specific flags. Must match the order above. */
+#define JIT_F_CPU_FIRST         JIT_F_MIPS32R2
+#define JIT_F_CPUSTRING         "\010MIPS32R2"
 #else
 #define JIT_F_CPU_FIRST         0
 #define JIT_F_CPUSTRING         ""