[PATCH 4/9] target/mips: Simplify MSA TCG logic

[Philippe Mathieu-Daudé <f4bug@xxxxxxxxx>]

Only decode MSA opcodes if MSA is present (implemented).

Now than check_msa_access() will only be called if MSA is
present, the only way to have MIPS_HFLAG_MSA unset is if
MSA is disabled (bit CP0C5_MSAEn cleared, see previous
commit). Therefore we can remove the 'reserved instruction'
exception.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@xxxxxxxxx>
---
 target/mips/translate.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/target/mips/translate.c b/target/mips/translate.c
index 803ffefba2c..a05c25e50b8 100644
--- a/target/mips/translate.c
+++ b/target/mips/translate.c
@@ -28697,13 +28697,8 @@ static inline int check_msa_access(DisasContext *ctx)
     }
 
     if (unlikely(!(ctx->hflags & MIPS_HFLAG_MSA))) {
-        if (ctx->insn_flags & ASE_MSA) {
-            generate_exception_end(ctx, EXCP_MSADIS);
-            return 0;
-        } else {
-            generate_exception_end(ctx, EXCP_RI);
-            return 0;
-        }
+        generate_exception_end(ctx, EXCP_MSADIS);
+        return 0;
     }
     return 1;
 }
@@ -30547,7 +30542,7 @@ static void gen_msa_vec(CPUMIPSState *env, DisasContext *ctx)
 static void gen_msa(CPUMIPSState *env, DisasContext *ctx)
 {
     uint32_t opcode = ctx->opcode;
-    check_insn(ctx, ASE_MSA);
+
     check_msa_access(ctx);
 
     switch (MASK_MSA_MINOR(opcode)) {
@@ -31194,9 +31189,10 @@ static void decode_opc(CPUMIPSState *env, DisasContext *ctx)
         case OPC_BNZ_H:
         case OPC_BNZ_W:
         case OPC_BNZ_D:
-            check_insn(ctx, ASE_MSA);
-            gen_msa_branch(env, ctx, op1);
-            break;
+            if (ase_msa_available(env)) {
+                gen_msa_branch(env, ctx, op1);
+                break;
+            }
         default:
             MIPS_INVAL("cp1");
             generate_exception_end(ctx, EXCP_RI);
@@ -31385,7 +31381,9 @@ static void decode_opc(CPUMIPSState *env, DisasContext *ctx)
 #endif
         } else {
             /* MDMX: Not implemented. */
-            gen_msa(env, ctx);
+            if (ase_msa_available(env)) {
+                gen_msa(env, ctx);
+            }
         }
         break;
     case OPC_PCREL:
-- 
2.26.2