[Qemu-devel] [PATCH 2/2] tcg: add TB sanity checking

[Max Filippov <jcmvbkbc@gmail.com>]

Do a sanity checking pass on the intermediate code.
Check that goto_tb indices are either 0 or 1 and used at most once per
TB.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
 tcg/tcg.c |   69 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 69 insertions(+), 0 deletions(-)

diff --git a/tcg/tcg.c b/tcg/tcg.c
index b8a1bec..cdd1975 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -1454,6 +1454,71 @@ static void check_regs(TCGContext *s)
 }
 #endif
 
+#ifdef CONFIG_DEBUG_TCG
+static void tcg_sanity_check(TCGContext *s)
+{
+    const uint16_t *opc_ptr;
+    const TCGArg *args;
+    TCGArg arg;
+    TCGOpcode c;
+    int nb_oargs, nb_iargs, nb_cargs, error_count = 0;
+    const TCGOpDef *def;
+    unsigned goto_tb_slots[2] = {0};
+
+    opc_ptr = gen_opc_buf;
+    args = gen_opparam_buf;
+    while (opc_ptr < gen_opc_ptr) {
+        c = *opc_ptr++;
+        def = &tcg_op_defs[c];
+        if (c == INDEX_op_call) {
+            TCGArg arg;
+
+            /* variable number of arguments */
+            arg = *args++;
+            nb_oargs = arg >> 16;
+            nb_iargs = arg & 0xffff;
+            nb_cargs = def->nb_cargs;
+        } else {
+            if (c == INDEX_op_nopn) {
+                /* variable number of arguments */
+                nb_cargs = *args;
+                nb_oargs = 0;
+                nb_iargs = 0;
+            } else {
+                nb_oargs = def->nb_oargs;
+                nb_iargs = def->nb_iargs;
+                nb_cargs = def->nb_cargs;
+            }
+        }
+
+        switch (c) {
+        case INDEX_op_goto_tb:
+            arg = args[0];
+            if (arg != 0 && arg != 1) {
+                qemu_log("TB ERROR: wrong goto_tb slot index: %"TCG_PRIlx"\n",
+                        arg);
+                ++error_count;
+            } else {
+                ++goto_tb_slots[arg];
+                if (goto_tb_slots[arg] > 1) {
+                    qemu_log("TB ERROR: multiple goto_tb(%"TCG_PRIlx")\n", arg);
+                    ++error_count;
+                }
+            }
+            break;
+
+        default:
+            break;
+        }
+
+        args += nb_iargs + nb_oargs + nb_cargs;
+    }
+    if (error_count) {
+        qemu_log("\n");
+    }
+}
+#endif
+
 static void temp_allocate_frame(TCGContext *s, int temp)
 {
     TCGTemp *ts;
@@ -2082,6 +2147,10 @@ static inline int tcg_gen_code_common(TCGContext *s, uint8_t *gen_code_buf,
     }
 #endif
 
+#ifdef CONFIG_DEBUG_TCG
+    tcg_sanity_check(s);
+#endif
+
     tcg_reg_alloc_start(s);
 
     s->code_buf = gen_code_buf;
-- 
1.7.7.6