1 /*

     2  * Copyright 1997-2005 Sun Microsystems, Inc.  All Rights Reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    24 

    25 inline void MacroAssembler::pd_patch_instruction(address branch, address target) {

    26   unsigned char op = branch[0];

    27   assert(op == 0xE8 /* call */ ||

    28          op == 0xE9 /* jmp */ ||

    29          op == 0xEB /* short jmp */ ||

    30          (op & 0xF0) == 0x70 /* short jcc */ ||

    31          op == 0x0F && (branch[1] & 0xF0) == 0x80 /* jcc */,

    32          "Invalid opcode at patch point");

    33 

    34   if (op == 0xEB || (op & 0xF0) == 0x70) {

    35     // short offset operators (jmp and jcc)

    36     char* disp = (char*) &branch[1];

    37     int imm8 = target - (address) &disp[1];

    38     guarantee(this->is8bit(imm8), "Short forward jump exceeds 8-bit offset");

    39     *disp = imm8;

    40   } else {

    41     int* disp = (int*) &branch[(op == 0x0F)? 2: 1];

    42     int imm32 = target - (address) &disp[1];

    43     *disp = imm32;

    44   }

    45 }

    46 

    47 #ifndef PRODUCT

    48 inline void MacroAssembler::pd_print_patched_instruction(address branch) {

    49   const char* s;

    50   unsigned char op = branch[0];

    51   if (op == 0xE8) {

    52     s = "call";

    53   } else if (op == 0xE9 || op == 0xEB) {

    54     s = "jmp";

    55   } else if ((op & 0xF0) == 0x70) {

    56     s = "jcc";

    57   } else if (op == 0x0F) {

    58     s = "jcc";

    59   } else {

    60     s = "????";

    61   }

    62   tty->print("%s (unresolved)", s);

    63 }

    64 #endif // ndef PRODUCT