Re: [PATCH 26/33] target/mips: Convert MSA ELM instruction format to decodetree

[Richard Henderson]

On 10/23/21 2:47 PM, Philippe Mathieu-Daudé wrote:
+static bool trans_msa_elm_df(DisasContext *ctx, arg_msa_elm *a,
+                             void (*gen_msa_elm_df)(TCGv_ptr, TCGv_i32,
+                                                    TCGv_i32, TCGv_i32,
+                                                    TCGv_i32))
+{
+    TCGv_i32 twd;
+    TCGv_i32 tws;
+    TCGv_i32 tdf;
+    TCGv_i32 tn;
+    uint32_t df, n;
+
+    if (!df_extract(df_elm, a->df, &df, &n)) {
+        gen_reserved_instruction(ctx);
+        return true;
+    }

Again, I think this should happen before the access check.

You could even return false from these extractions, because they represent an invalid 
encoding for this instruction.  In a different context, there could be another grouped 
insn that matches.


+    twd = tcg_const_i32(a->wd);
+    tws = tcg_const_i32(a->ws);

tcg_constant_i32.

r~