From 26ab4d6560546274638560855bd16b29319818a4 Mon Sep 17 00:00:00 2001
From: Richard Henderson <richard.henderson@linaro.org>
Date: Sat, 5 Jan 2019 06:39:04 -0500
Subject: [PATCH] tcg: Reference count labels

Increment when adding branches, and decrement when removing them.

Backports commit d88a117eaa39b1d0eb1a79fe84c81840a39eb233 from qemu
---
 qemu/tcg/tcg-op.c |  2 ++
 qemu/tcg/tcg-op.h |  1 +
 qemu/tcg/tcg.c    | 20 ++++++++++++++++++++
 qemu/tcg/tcg.h    |  3 ++-
 4 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/qemu/tcg/tcg-op.c b/qemu/tcg/tcg-op.c
index 46b408b5..472bc843 100644
--- a/qemu/tcg/tcg-op.c
+++ b/qemu/tcg/tcg-op.c
@@ -240,6 +240,7 @@ void tcg_gen_brcond_i32(TCGContext *s, TCGCond cond, TCGv_i32 arg1, TCGv_i32 arg
     if (cond == TCG_COND_ALWAYS) {
         tcg_gen_br(s, l);
     } else if (cond != TCG_COND_NEVER) {
+        l->refs++;
         tcg_gen_op4ii_i32(s, INDEX_op_brcond_i32, arg1, arg2, cond, label_arg(s, l));
     }
 }
@@ -1412,6 +1413,7 @@ void tcg_gen_brcond_i64(TCGContext *s, TCGCond cond, TCGv_i64 arg1, TCGv_i64 arg
     if (cond == TCG_COND_ALWAYS) {
         tcg_gen_br(s, l);
     } else if (cond != TCG_COND_NEVER) {
+        l->refs++;
         if (TCG_TARGET_REG_BITS == 32) {
             tcg_gen_op6ii_i32(s, INDEX_op_brcond2_i32, TCGV_LOW(s, arg1),
                               TCGV_HIGH(s, arg1), TCGV_LOW(s, arg2),
diff --git a/qemu/tcg/tcg-op.h b/qemu/tcg/tcg-op.h
index 0aefa047..92fdd1f2 100644
--- a/qemu/tcg/tcg-op.h
+++ b/qemu/tcg/tcg-op.h
@@ -273,6 +273,7 @@ static inline void gen_set_label(TCGContext *s, TCGLabel *l)
 
 static inline void tcg_gen_br(TCGContext *s, TCGLabel *l)
 {
+    l->refs++;
     tcg_gen_op1(s, INDEX_op_br, label_arg(s, l));
 }
 
diff --git a/qemu/tcg/tcg.c b/qemu/tcg/tcg.c
index d841491e..3ef03b57 100644
--- a/qemu/tcg/tcg.c
+++ b/qemu/tcg/tcg.c
@@ -1678,6 +1678,26 @@ static void process_op_defs(TCGContext *s)
 
 void tcg_op_remove(TCGContext *s, TCGOp *op)
 {
+    TCGLabel *label;
+
+    switch (op->opc) {
+    case INDEX_op_br:
+        label = arg_label(s, op->args[0]);
+        label->refs--;
+        break;
+    case INDEX_op_brcond_i32:
+    case INDEX_op_brcond_i64:
+        label = arg_label(s, op->args[3]);
+        label->refs--;
+        break;
+    case INDEX_op_brcond2_i32:
+        label = arg_label(s, op->args[5]);
+        label->refs--;
+        break;
+    default:
+        break;
+    }
+
     QTAILQ_REMOVE(&s->ops, op, link);
     QTAILQ_INSERT_TAIL(&s->free_ops, op, link);
     s->nb_ops--;
diff --git a/qemu/tcg/tcg.h b/qemu/tcg/tcg.h
index fab7857e..b4097b56 100644
--- a/qemu/tcg/tcg.h
+++ b/qemu/tcg/tcg.h
@@ -250,7 +250,8 @@ typedef struct TCGRelocation {
 
 typedef struct TCGLabel {
     unsigned has_value : 1;
-    unsigned id : 31;
+    unsigned id : 15;
+    unsigned refs : 16;
     union {
         uintptr_t value;
         tcg_insn_unit *value_ptr;