tcg: correctly mark dead inputs for mov with a constant

When tcg_reg_alloc_mov propagate a constant, we failed to correctly mark
a temp as dead if the liveness analysis hints so. This fixes the
following assert when configure with --enable-debug-tcg:

  qemu-x86_64: tcg/tcg.c:1827: tcg_reg_alloc_bb_end: Assertion `ts->val_type == TEMP_VAL_DEAD' failed.

Cc: Richard Henderson <rth@twiddle.net>
Reported-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Message-Id: <1437994568-7825-2-git-send-email-aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>

tcg/tcg.c

@@ -1920,6 +1920,9 @@ static void tcg_reg_alloc_mov(TCGContext *s, const TCGOpDef *def,
         }
         ots->val_type = TEMP_VAL_CONST;
         ots->val = ts->val;
+        if (IS_DEAD_ARG(1)) {
+            temp_dead(s, args[1]);
+        }
     } else {
         /* The code in the first if block should have moved the
            temp to a register. */