diff mbox series

[v2,02/28] target/alpha: Remove use_exit_tb

Message ID 20210630183226.3290849-3-richard.henderson@linaro.org
State Superseded
Headers show
Series accel/tcg: Introduce translator_use_goto_tb | expand

Commit Message

Richard Henderson June 30, 2021, 6:32 p.m. UTC 
We have not needed to end a TB for I/O since ba3e7926691
("icount: clean up cpu_can_io at the entry to the block").
We do not need to use exit_tb for singlestep, which only
means generate one insn per TB.

Which leaves only singlestep_enabled, which means raise a
debug trap after every TB, which does not use exit_tb,
which would leave the function mis-named.

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

---
 target/alpha/translate.c | 15 ++-------------
 1 file changed, 2 insertions(+), 13 deletions(-)

-- 
2.25.1

Comments

Peter Maydell July 8, 2021, 12:34 p.m. UTC | #1 
On Wed, 30 Jun 2021 at 19:39, Richard Henderson
<richard.henderson@linaro.org> wrote:
>

> We have not needed to end a TB for I/O since ba3e7926691

> ("icount: clean up cpu_can_io at the entry to the block").

> We do not need to use exit_tb for singlestep, which only

> means generate one insn per TB.

>

> Which leaves only singlestep_enabled, which means raise a

> debug trap after every TB, which does not use exit_tb,

> which would leave the function mis-named.

>

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


Reviewed-by: Peter Maydell <peter.maydell@linaro.org>


I wonder if we should rename the 'singlestep' global to
'tcg_one_insn_per_tb' or something (and perhaps also provide a
new command line flag, with the old one deprecated). It's very
misleadingly named...

thanks
-- PMM
diff mbox series

Patch

diff --git a/target/alpha/translate.c b/target/alpha/translate.c
index f2922f5f8c..aaedf78116 100644
--- a/target/alpha/translate.c
+++ b/target/alpha/translate.c
@@ -450,19 +450,8 @@  static bool in_superpage(DisasContext *ctx, int64_t addr)
 #endif
 }
 
-static bool use_exit_tb(DisasContext *ctx)
-{
-    return ((tb_cflags(ctx->base.tb) & CF_LAST_IO)
-            || ctx->base.singlestep_enabled
-            || singlestep);
-}
-
 static bool use_goto_tb(DisasContext *ctx, uint64_t dest)
 {
-    /* Suppress goto_tb in the case of single-steping and IO.  */
-    if (unlikely(use_exit_tb(ctx))) {
-        return false;
-    }
 #ifndef CONFIG_USER_ONLY
     /* If the destination is in the superpage, the page perms can't change.  */
     if (in_superpage(ctx, dest)) {
@@ -1271,7 +1260,7 @@  static DisasJumpType gen_call_pal(DisasContext *ctx, int palcode)
            need the page permissions check.  We'll see the existence of
            the page when we create the TB, and we'll flush all TBs if
            we change the PAL base register.  */
-        if (!use_exit_tb(ctx)) {
+        if (!ctx->base.singlestep_enabled) {
             tcg_gen_goto_tb(0);
             tcg_gen_movi_i64(cpu_pc, entry);
             tcg_gen_exit_tb(ctx->base.tb, 0);
@@ -3095,7 +3084,7 @@  static void alpha_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
         tcg_gen_movi_i64(cpu_pc, ctx->base.pc_next);
         /* FALLTHRU */
     case DISAS_PC_UPDATED:
-        if (!use_exit_tb(ctx)) {
+        if (!ctx->base.singlestep_enabled) {
             tcg_gen_lookup_and_goto_ptr();
             break;
         }