target/mips: Support the R5900 LQ multimedia instruction [#4]

Signed-off-by: Fredrik Noring <noring@nocrew.org>

target/mips/translate.c

@@ -2626,6 +2626,17 @@ static inline void gen_store_gpr (TCGv t, int reg)
         tcg_gen_mov_tl(cpu_gpr[reg], t);
 }
 
+#if defined(TARGET_MIPS64)
+/* 128-bit multimedia register moves. */
+static inline void gen_store_mmr(TCGv_i64 hi, TCGv_i64 lo, int reg)
+{
+    if (reg != 0) {
+        tcg_gen_mov_i64(cpu_mmr[reg], hi);
+        tcg_gen_mov_i64(cpu_gpr[reg], lo);
+    }
+}
+#endif /* defined(TARGET_MIPS64) */
+
 /* Moves to/from shadow registers. */
 static inline void gen_load_srsgpr (int from, int to)
 {
@@ -27465,7 +27476,40 @@ static void decode_mmi(CPUMIPSState *env, DisasContext *ctx)
 
 static void gen_mmi_lq(CPUMIPSState *env, DisasContext *ctx)
 {
-    generate_exception_end(ctx, EXCP_RI);    /* TODO: MMI_OPC_LQ */
+#if !defined(TARGET_MIPS64)
+    generate_exception_end(ctx, EXCP_RI);
+#else
+    int base = extract32(ctx->opcode, 21, 5);
+    int rt = extract32(ctx->opcode, 16, 5);
+    int offset = sextract32(ctx->opcode, 0, 16);
+
+    TCGv_i64 addr = tcg_temp_new_i64();
+    TCGv_i64 val0 = tcg_temp_new_i64();
+    TCGv_i64 val1 = tcg_temp_new_i64();
+
+    gen_base_offset_addr(ctx, addr, base, offset);
+
+    /*
+     * The least significant four bits of the effective address are
+     * masked to zero, effectively creating an aligned address. No
+     * address exceptions due to alignment are possible.
+     */
+    tcg_gen_andi_i64(addr, addr, ~0xFULL);
+
+    tcg_gen_qemu_ld_i64(val0, addr, ctx->mem_idx, MO_UNALN | MO_64);
+    tcg_gen_addi_i64(addr, addr, 8);
+    tcg_gen_qemu_ld_i64(val1, addr, ctx->mem_idx, MO_UNALN | MO_64);
+
+#if defined(TARGET_WORDS_BIGENDIAN)
+    gen_store_mmr(val0, val1, rt);
+#else
+    gen_store_mmr(val1, val0, rt);
+#endif
+
+    tcg_temp_free_i64(val1);
+    tcg_temp_free_i64(val0);
+    tcg_temp_free_i64(addr);
+#endif /* defined(TARGET_MIPS64) */
 }
 
 static void gen_mmi_sq(DisasContext *ctx, int base, int rt, int offset)