diff mbox series

[v2,3/6] target/mips: Have gen_[d]lsa() callers add 1 to shift amount argument

Message ID 20241112172022.88348-4-philmd@linaro.org
State Superseded
Headers show
Series target/mips: Convert nanoMIPS LSA opcode to decodetree | expand

Commit Message

Philippe Mathieu-Daudé Nov. 12, 2024, 5:20 p.m. UTC 
Having the callee add 1 to shift amount is misleading (see the
NM_LSA case in decode_nanomips_32_48_opc() where we have to
manually substract 1). Rather have the callers pass a modified
$sa.

Suggested-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
---
 target/mips/tcg/msa_translate.c           | 4 ++--
 target/mips/tcg/rel6_translate.c          | 4 ++--
 target/mips/tcg/translate_addr_const.c    | 4 ++--
 target/mips/tcg/micromips_translate.c.inc | 2 +-
 target/mips/tcg/nanomips_translate.c.inc  | 7 +------
 5 files changed, 8 insertions(+), 13 deletions(-)

Comments

Richard Henderson Nov. 12, 2024, 6:16 p.m. UTC | #1 
On 11/12/24 09:20, Philippe Mathieu-Daudé wrote:
> Having the callee add 1 to shift amount is misleading (see the
> NM_LSA case in decode_nanomips_32_48_opc() where we have to
> manually substract 1). Rather have the callers pass a modified
> $sa.
> 
> Suggested-by: Richard Henderson<richard.henderson@linaro.org>
> Signed-off-by: Philippe Mathieu-Daudé<philmd@linaro.org>
> ---
>   target/mips/tcg/msa_translate.c           | 4 ++--
>   target/mips/tcg/rel6_translate.c          | 4 ++--
>   target/mips/tcg/translate_addr_const.c    | 4 ++--
>   target/mips/tcg/micromips_translate.c.inc | 2 +-
>   target/mips/tcg/nanomips_translate.c.inc  | 7 +------
>   5 files changed, 8 insertions(+), 13 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~
diff mbox series

Patch

diff --git a/target/mips/tcg/msa_translate.c b/target/mips/tcg/msa_translate.c
index 75cf80a20e..82b149922f 100644
--- a/target/mips/tcg/msa_translate.c
+++ b/target/mips/tcg/msa_translate.c
@@ -780,7 +780,7 @@  TRANS_DF_iv(ST, trans_msa_ldst, gen_helper_msa_st);
 
 static bool trans_LSA(DisasContext *ctx, arg_r *a)
 {
-    return gen_lsa(ctx, a->rd, a->rt, a->rs, a->sa);
+    return gen_lsa(ctx, a->rd, a->rt, a->rs, a->sa + 1);
 }
 
 static bool trans_DLSA(DisasContext *ctx, arg_r *a)
@@ -788,5 +788,5 @@  static bool trans_DLSA(DisasContext *ctx, arg_r *a)
     if (TARGET_LONG_BITS != 64) {
         return false;
     }
-    return gen_dlsa(ctx, a->rd, a->rt, a->rs, a->sa);
+    return gen_dlsa(ctx, a->rd, a->rt, a->rs, a->sa + 1);
 }
diff --git a/target/mips/tcg/rel6_translate.c b/target/mips/tcg/rel6_translate.c
index 59f237ba3b..363bc86491 100644
--- a/target/mips/tcg/rel6_translate.c
+++ b/target/mips/tcg/rel6_translate.c
@@ -23,7 +23,7 @@  bool trans_REMOVED(DisasContext *ctx, arg_REMOVED *a)
 
 static bool trans_LSA(DisasContext *ctx, arg_r *a)
 {
-    return gen_lsa(ctx, a->rd, a->rt, a->rs, a->sa);
+    return gen_lsa(ctx, a->rd, a->rt, a->rs, a->sa + 1);
 }
 
 static bool trans_DLSA(DisasContext *ctx, arg_r *a)
@@ -31,5 +31,5 @@  static bool trans_DLSA(DisasContext *ctx, arg_r *a)
     if (TARGET_LONG_BITS != 64) {
         return false;
     }
-    return gen_dlsa(ctx, a->rd, a->rt, a->rs, a->sa);
+    return gen_dlsa(ctx, a->rd, a->rt, a->rs, a->sa + 1);
 }
diff --git a/target/mips/tcg/translate_addr_const.c b/target/mips/tcg/translate_addr_const.c
index 6f4b39f715..1d140e918d 100644
--- a/target/mips/tcg/translate_addr_const.c
+++ b/target/mips/tcg/translate_addr_const.c
@@ -26,7 +26,7 @@  bool gen_lsa(DisasContext *ctx, int rd, int rt, int rs, int sa)
     t1 = tcg_temp_new();
     gen_load_gpr(t0, rs);
     gen_load_gpr(t1, rt);
-    tcg_gen_shli_tl(t0, t0, sa + 1);
+    tcg_gen_shli_tl(t0, t0, sa);
     tcg_gen_add_tl(cpu_gpr[rd], t0, t1);
     tcg_gen_ext32s_tl(cpu_gpr[rd], cpu_gpr[rd]);
     return true;
@@ -47,7 +47,7 @@  bool gen_dlsa(DisasContext *ctx, int rd, int rt, int rs, int sa)
     t1 = tcg_temp_new();
     gen_load_gpr(t0, rs);
     gen_load_gpr(t1, rt);
-    tcg_gen_shli_tl(t0, t0, sa + 1);
+    tcg_gen_shli_tl(t0, t0, sa);
     tcg_gen_add_tl(cpu_gpr[rd], t0, t1);
     return true;
 }
diff --git a/target/mips/tcg/micromips_translate.c.inc b/target/mips/tcg/micromips_translate.c.inc
index f504e15fa7..e8ec5a0ff2 100644
--- a/target/mips/tcg/micromips_translate.c.inc
+++ b/target/mips/tcg/micromips_translate.c.inc
@@ -1795,7 +1795,7 @@  static void decode_micromips32_opc(CPUMIPSState *env, DisasContext *ctx)
             return;
         case LSA:
             check_insn(ctx, ISA_MIPS_R6);
-            gen_lsa(ctx, rd, rt, rs, extract32(ctx->opcode, 9, 2));
+            gen_lsa(ctx, rd, rt, rs, extract32(ctx->opcode, 9, 2) + 1);
             break;
         case ALIGN:
             check_insn(ctx, ISA_MIPS_R6);
diff --git a/target/mips/tcg/nanomips_translate.c.inc b/target/mips/tcg/nanomips_translate.c.inc
index e401b92bfd..e118013edc 100644
--- a/target/mips/tcg/nanomips_translate.c.inc
+++ b/target/mips/tcg/nanomips_translate.c.inc
@@ -3626,12 +3626,7 @@  static int decode_nanomips_32_48_opc(CPUMIPSState *env, DisasContext *ctx)
                 gen_p_lsx(ctx, rd, rs, rt);
                 break;
             case NM_LSA:
-                /*
-                 * In nanoMIPS, the shift field directly encodes the shift
-                 * amount, meaning that the supported shift values are in
-                 * the range 0 to 3 (instead of 1 to 4 in MIPSR6).
-                 */
-                gen_lsa(ctx, rd, rt, rs, extract32(ctx->opcode, 9, 2) - 1);
+                gen_lsa(ctx, rd, rt, rs, extract32(ctx->opcode, 9, 2));
                 break;
             case NM_EXTW:
                 gen_ext(ctx, 32, rd, rs, rt, extract32(ctx->opcode, 6, 5));