[Qemu-devel] [5845] Don't rely on ARM tcg_out_goto() generating just a single insn.

[Andrzej Zaborowski]

Revision: 5845
          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=5845
Author:   balrog
Date:     2008-12-01 02:17:12 +0000 (Mon, 01 Dec 2008)

Log Message:
-----------
Don't rely on ARM tcg_out_goto() generating just a single insn.

Otherwise when tb_exit generates a jump beyond the pc-relative range,
tcg_out_goto() spans two/three instructions and we load the tb return
value from a wrong address.  This is #ifdefed out currently because
we take care for the jumps to be local.
Problem spotted by Steffen Liebergeld.

Modified Paths:
--------------
    trunk/tcg/arm/tcg-target.c

Modified: trunk/tcg/arm/tcg-target.c
===================================================================
--- trunk/tcg/arm/tcg-target.c  2008-12-01 02:10:17 UTC (rev 5844)
+++ trunk/tcg/arm/tcg-target.c  2008-12-01 02:17:12 UTC (rev 5845)
@@ -1232,19 +1232,24 @@
         if (args[0] >> 8)
             tcg_out32(s, args[0]);
 #else
-        if (args[0] >> 8)
-            tcg_out_ld32_12(s, COND_AL, 0, 15, 0);
-        else
-            tcg_out_dat_imm(s, COND_AL, ARITH_MOV, 0, 0, args[0]);
-        tcg_out_goto(s, COND_AL, (tcg_target_ulong) tb_ret_addr);
-        if (args[0] >> 8)
-            tcg_out32(s, args[0]);
+        {
+            uint8_t *ld_ptr = s->code_ptr;
+            if (args[0] >> 8)
+                tcg_out_ld32_12(s, COND_AL, 0, 15, 0);
+            else
+                tcg_out_dat_imm(s, COND_AL, ARITH_MOV, 0, 0, args[0]);
+            tcg_out_goto(s, COND_AL, (tcg_target_ulong) tb_ret_addr);
+            if (args[0] >> 8) {
+                *ld_ptr = (uint8_t) (s->code_ptr - ld_ptr) - 8;
+                tcg_out32(s, args[0]);
+            }
+        }
 #endif
         break;
     case INDEX_op_goto_tb:
         if (s->tb_jmp_offset) {
             /* Direct jump method */
-#if 1
+#if defined(USE_DIRECT_JUMP)
             s->tb_jmp_offset[args[0]] = s->code_ptr - s->code_buf;
             tcg_out_b(s, COND_AL, 8);
 #else