tcg: distribute profiling counters across TCGContext's

This is groundwork for supporting multiple TCG contexts.

To avoid scalability issues when profiling info is enabled, this patch
makes the profiling info counters distributed via the following changes:

1) Consolidate profile info into its own struct, TCGProfile, which
   TCGContext also includes. Note that tcg_table_op_count is brought
   into TCGProfile after dropping the tcg_ prefix.
2) Iterate over the TCG contexts in the system to obtain the total counts.

This change also requires updating the accessors to TCGProfile fields to
use atomic_read/set whenever there may be conflicting accesses (as defined
in C11) to them.

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

2 files changed, 113 insertions, 35 deletions

diff --git a/tcg/tcg.c b/tcg/tcg.c
index 24ef6df..f1bbfe3 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -1547,7 +1547,7 @@ void tcg_op_remove(TCGContext *s, TCGOp *op)
     memset(op, 0, sizeof(*op));
 
 #ifdef CONFIG_PROFILER
-    s->del_op_count++;
+    atomic_set(&s->prof.del_op_count, s->prof.del_op_count + 1);
 #endif
 }
 
@@ -2715,15 +2715,79 @@ static void tcg_reg_alloc_call(TCGContext *s, TCGOp *op)
 
 #ifdef CONFIG_PROFILER
 
-static int64_t tcg_table_op_count[NB_OPS];
+/* avoid copy/paste errors */
+#define PROF_ADD(to, from, field)                       \
+    do {                                                \
+        (to)->field += atomic_read(&((from)->field));   \
+    } while (0)
+
+#define PROF_MAX(to, from, field)                                       \
+    do {                                                                \
+        typeof((from)->field) val__ = atomic_read(&((from)->field));    \
+        if (val__ > (to)->field) {                                      \
+            (to)->field = val__;                                        \
+        }                                                               \
+    } while (0)
+
+/* Pass in a zero'ed @prof */
+static inline
+void tcg_profile_snapshot(TCGProfile *prof, bool counters, bool table)
+{
+    unsigned int i;
+
+    for (i = 0; i < n_tcg_ctxs; i++) {
+        const TCGProfile *orig = &tcg_ctxs[i]->prof;
+
+        if (counters) {
+            PROF_ADD(prof, orig, tb_count1);
+            PROF_ADD(prof, orig, tb_count);
+            PROF_ADD(prof, orig, op_count);
+            PROF_MAX(prof, orig, op_count_max);
+            PROF_ADD(prof, orig, temp_count);
+            PROF_MAX(prof, orig, temp_count_max);
+            PROF_ADD(prof, orig, del_op_count);
+            PROF_ADD(prof, orig, code_in_len);
+            PROF_ADD(prof, orig, code_out_len);
+            PROF_ADD(prof, orig, search_out_len);
+            PROF_ADD(prof, orig, interm_time);
+            PROF_ADD(prof, orig, code_time);
+            PROF_ADD(prof, orig, la_time);
+            PROF_ADD(prof, orig, opt_time);
+            PROF_ADD(prof, orig, restore_count);
+            PROF_ADD(prof, orig, restore_time);
+        }
+        if (table) {
+            int i;
+
+            for (i = 0; i < NB_OPS; i++) {
+                PROF_ADD(prof, orig, table_op_count[i]);
+            }
+        }
+    }
+}
+
+#undef PROF_ADD
+#undef PROF_MAX
+
+static void tcg_profile_snapshot_counters(TCGProfile *prof)
+{
+    tcg_profile_snapshot(prof, true, false);
+}
+
+static void tcg_profile_snapshot_table(TCGProfile *prof)
+{
+    tcg_profile_snapshot(prof, false, true);
+}
 
 void tcg_dump_op_count(FILE *f, fprintf_function cpu_fprintf)
 {
+    TCGProfile prof = {};
     int i;
 
+    tcg_profile_snapshot_table(&prof);
     for (i = 0; i < NB_OPS; i++) {
         cpu_fprintf(f, "%s %" PRId64 "\n", tcg_op_defs[i].name,
-                    tcg_table_op_count[i]);
+                    prof.table_op_count[i]);
     }
 }
 #else
@@ -2736,6 +2800,9 @@ void tcg_dump_op_count(FILE *f, fprintf_function cpu_fprintf)
 
 int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
 {
+#ifdef CONFIG_PROFILER
+    TCGProfile *prof = &s->prof;
+#endif
     int i, oi, oi_next, num_insns;
 
 #ifdef CONFIG_PROFILER
@@ -2743,15 +2810,15 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
         int n;
 
         n = s->gen_op_buf[0].prev + 1;
-        s->op_count += n;
-        if (n > s->op_count_max) {
-            s->op_count_max = n;
+        atomic_set(&prof->op_count, prof->op_count + n);
+        if (n > prof->op_count_max) {
+            atomic_set(&prof->op_count_max, n);
         }
 
         n = s->nb_temps;
-        s->temp_count += n;
-        if (n > s->temp_count_max) {
-            s->temp_count_max = n;
+        atomic_set(&prof->temp_count, prof->temp_count + n);
+        if (n > prof->temp_count_max) {
+            atomic_set(&prof->temp_count_max, n);
         }
     }
 #endif
@@ -2768,7 +2835,7 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
 #endif
 
 #ifdef CONFIG_PROFILER
-    s->opt_time -= profile_getclock();
+    atomic_set(&prof->opt_time, prof->opt_time - profile_getclock());
 #endif
 
 #ifdef USE_TCG_OPTIMIZATIONS
@@ -2776,8 +2843,8 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
 #endif
 
 #ifdef CONFIG_PROFILER
-    s->opt_time += profile_getclock();
-    s->la_time -= profile_getclock();
+    atomic_set(&prof->opt_time, prof->opt_time + profile_getclock());
+    atomic_set(&prof->la_time, prof->la_time - profile_getclock());
 #endif
 
     liveness_pass_1(s);
@@ -2801,7 +2868,7 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
     }
 
 #ifdef CONFIG_PROFILER
-    s->la_time += profile_getclock();
+    atomic_set(&prof->la_time, prof->la_time + profile_getclock());
 #endif
 
 #ifdef DEBUG_DISAS
@@ -2834,7 +2901,7 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
 
         oi_next = op->next;
 #ifdef CONFIG_PROFILER
-        tcg_table_op_count[opc]++;
+        atomic_set(&prof->table_op_count[opc], prof->table_op_count[opc] + 1);
 #endif
 
         switch (opc) {
@@ -2915,10 +2982,17 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
 #ifdef CONFIG_PROFILER
 void tcg_dump_info(FILE *f, fprintf_function cpu_fprintf)
 {
-    TCGContext *s = tcg_ctx;
-    int64_t tb_count = s->tb_count;
-    int64_t tb_div_count = tb_count ? tb_count : 1;
-    int64_t tot = s->interm_time + s->code_time;
+    TCGProfile prof = {};
+    const TCGProfile *s;
+    int64_t tb_count;
+    int64_t tb_div_count;
+    int64_t tot;
+
+    tcg_profile_snapshot_counters(&prof);
+    s = &prof;
+    tb_count = s->tb_count;
+    tb_div_count = tb_count ? tb_count : 1;
+    tot = s->interm_time + s->code_time;
 
     cpu_fprintf(f, "JIT cycles          %" PRId64 " (%0.3f s at 2.4 GHz)\n",
                 tot, tot / 2.4e9);
diff --git a/tcg/tcg.h b/tcg/tcg.h
index cca85b4..4b9958a 100644
--- a/tcg/tcg.h
+++ b/tcg/tcg.h
@@ -599,6 +599,26 @@ QEMU_BUILD_BUG_ON(sizeof(TCGOp) != 8 + sizeof(TCGArg) * MAX_OPC_PARAM);
 QEMU_BUILD_BUG_ON(NB_OPS > (1 << 8));
 QEMU_BUILD_BUG_ON(OPC_BUF_SIZE > (1 << 16));
 
+typedef struct TCGProfile {
+    int64_t tb_count1;
+    int64_t tb_count;
+    int64_t op_count; /* total insn count */
+    int op_count_max; /* max insn per TB */
+    int64_t temp_count;
+    int temp_count_max;
+    int64_t del_op_count;
+    int64_t code_in_len;
+    int64_t code_out_len;
+    int64_t search_out_len;
+    int64_t interm_time;
+    int64_t code_time;
+    int64_t la_time;
+    int64_t opt_time;
+    int64_t restore_count;
+    int64_t restore_time;
+    int64_t table_op_count[NB_OPS];
+} TCGProfile;
+
 struct TCGContext {
     uint8_t *pool_cur, *pool_end;
     TCGPool *pool_first, *pool_current, *pool_first_large;
@@ -623,23 +643,7 @@ struct TCGContext {
     tcg_insn_unit *code_ptr;
 
 #ifdef CONFIG_PROFILER
-    /* profiling info */
-    int64_t tb_count1;
-    int64_t tb_count;
-    int64_t op_count; /* total insn count */
-    int op_count_max; /* max insn per TB */
-    int64_t temp_count;
-    int temp_count_max;
-    int64_t del_op_count;
-    int64_t code_in_len;
-    int64_t code_out_len;
-    int64_t search_out_len;
-    int64_t interm_time;
-    int64_t code_time;
-    int64_t la_time;
-    int64_t opt_time;
-    int64_t restore_count;
-    int64_t restore_time;
+    TCGProfile prof;
 #endif
 
 #ifdef CONFIG_DEBUG_TCG