[PATCH v2 03/10] accel/tcg: Add CF_NO_GOTO_TB and CF_NO_GOTO_PTR

[Richard Henderson]

Move the -d nochain check to bits on tb->cflags.
These will be used for more than -d nochain shortly.

Set bits during curr_cflags, test them in translator_use_goto_tb,
assert we're not doing anything odd in tcg_gen_goto_tb.  The test
in tcg_gen_exit_tb is redundant with the assert for goto_tb_issue_mask.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 include/exec/exec-all.h | 16 +++++++++-------
 accel/tcg/cpu-exec.c    |  8 +++++++-
 accel/tcg/translator.c  |  5 +++++
 tcg/tcg-op.c            | 28 ++++++++++++----------------
 4 files changed, 33 insertions(+), 24 deletions(-)

diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index ae7603ca75..6873cce8df 100644
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -494,13 +494,15 @@ struct TranslationBlock {
     uint32_t cflags;    /* compile flags */
 
 /* Note that TCG_MAX_INSNS is 512; we validate this match elsewhere. */
-#define CF_COUNT_MASK  0x000001ff
-#define CF_LAST_IO     0x00008000 /* Last insn may be an IO access.  */
-#define CF_MEMI_ONLY   0x00010000 /* Only instrument memory ops */
-#define CF_USE_ICOUNT  0x00020000
-#define CF_INVALID     0x00040000 /* TB is stale. Set with @jmp_lock held */
-#define CF_PARALLEL    0x00080000 /* Generate code for a parallel context */
-#define CF_CLUSTER_MASK 0xff000000 /* Top 8 bits are cluster ID */
+#define CF_COUNT_MASK    0x000001ff
+#define CF_NO_GOTO_TB    0x00000200 /* Do not chain with goto_tb */
+#define CF_NO_GOTO_PTR   0x00000400 /* Do not chain with goto_ptr */
+#define CF_LAST_IO       0x00008000 /* Last insn may be an IO access.  */
+#define CF_MEMI_ONLY     0x00010000 /* Only instrument memory ops */
+#define CF_USE_ICOUNT    0x00020000
+#define CF_INVALID       0x00040000 /* TB is stale. Set with @jmp_lock held */
+#define CF_PARALLEL      0x00080000 /* Generate code for a parallel context */
+#define CF_CLUSTER_MASK  0xff000000 /* Top 8 bits are cluster ID */
 #define CF_CLUSTER_SHIFT 24
 
     /* Per-vCPU dynamic tracing state used to generate this TB */
diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index ef4214d893..d3232d5764 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -147,7 +147,13 @@ static void init_delay_params(SyncClocks *sc, const 
CPUState *cpu)
 
 uint32_t curr_cflags(CPUState *cpu)
 {
-    return cpu->tcg_cflags;
+    uint32_t cflags = cpu->tcg_cflags;
+
+    if (qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) {
+        cflags |= CF_NO_GOTO_TB | CF_NO_GOTO_PTR;
+    }
+
+    return cflags;
 }
 
 /* Might cause an exception, so have a longjmp destination ready */
diff --git a/accel/tcg/translator.c b/accel/tcg/translator.c
index 59804af37b..2ea5a74f30 100644
--- a/accel/tcg/translator.c
+++ b/accel/tcg/translator.c
@@ -33,6 +33,11 @@ void translator_loop_temp_check(DisasContextBase *db)
 
 bool translator_use_goto_tb(DisasContextBase *db, target_ulong dest)
 {
+    /* Suppress goto_tb if requested. */
+    if (tb_cflags(db->tb) & CF_NO_GOTO_TB) {
+        return false;
+    }
+
     /* Suppress goto_tb in the case of single-steping.  */
     if (db->singlestep_enabled || singlestep) {
         return false;
diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c
index 0c561fb253..e0d54d537f 100644
--- a/tcg/tcg-op.c
+++ b/tcg/tcg-op.c
@@ -2723,10 +2723,6 @@ void tcg_gen_exit_tb(const TranslationBlock *tb, 
unsigned idx)
            seen this numbered exit before, via tcg_gen_goto_tb.  */
         tcg_debug_assert(tcg_ctx->goto_tb_issue_mask & (1 << idx));
 #endif
-        /* When not chaining, exit without indicating a link.  */
-        if (qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) {
-            val = 0;
-        }
     } else {
         /* This is an exit via the exitreq label.  */
         tcg_debug_assert(idx == TB_EXIT_REQUESTED);
@@ -2738,6 +2734,8 @@ void tcg_gen_exit_tb(const TranslationBlock *tb, unsigned 
idx)
 
 void tcg_gen_goto_tb(unsigned idx)
 {
+    /* We tested CF_NO_GOTO_TB in translator_use_goto_tb. */
+    tcg_debug_assert(!(tcg_ctx->tb_cflags & CF_NO_GOTO_TB));
     /* We only support two chained exits.  */
     tcg_debug_assert(idx <= TB_EXIT_IDXMAX);
 #ifdef CONFIG_DEBUG_TCG
@@ -2746,25 +2744,23 @@ void tcg_gen_goto_tb(unsigned idx)
     tcg_ctx->goto_tb_issue_mask |= 1 << idx;
 #endif
     plugin_gen_disable_mem_helpers();
-    /* When not chaining, we simply fall through to the "fallback" exit.  */
-    if (!qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) {
-        tcg_gen_op1i(INDEX_op_goto_tb, idx);
-    }
+    tcg_gen_op1i(INDEX_op_goto_tb, idx);
 }
 
 void tcg_gen_lookup_and_goto_ptr(void)
 {
-    if (!qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) {
-        TCGv_ptr ptr;
+    TCGv_ptr ptr;
 
-        plugin_gen_disable_mem_helpers();
-        ptr = tcg_temp_new_ptr();
-        gen_helper_lookup_tb_ptr(ptr, cpu_env);
-        tcg_gen_op1i(INDEX_op_goto_ptr, tcgv_ptr_arg(ptr));
-        tcg_temp_free_ptr(ptr);
-    } else {
+    if (tcg_ctx->tb_cflags & CF_NO_GOTO_PTR) {
         tcg_gen_exit_tb(NULL, 0);
+        return;
     }
+
+    plugin_gen_disable_mem_helpers();
+    ptr = tcg_temp_new_ptr();
+    gen_helper_lookup_tb_ptr(ptr, cpu_env);
+    tcg_gen_op1i(INDEX_op_goto_ptr, tcgv_ptr_arg(ptr));
+    tcg_temp_free_ptr(ptr);
 }
 
 static inline MemOp tcg_canonicalize_memop(MemOp op, bool is64, bool st)
-- 
2.25.1