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      1 /* Windows i386 support code for fibers and multithreading.
      2    Copyright (C) 2019-2022 Free Software Foundation, Inc.
      3 
      4 This file is part of GCC.
      5 
      6 GCC is free software; you can redistribute it and/or modify it under
      7 the terms of the GNU General Public License as published by the Free
      8 Software Foundation; either version 3, or (at your option) any later
      9 version.
     10 
     11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
     12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
     13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
     14 for more details.
     15 
     16 Under Section 7 of GPL version 3, you are granted additional
     17 permissions described in the GCC Runtime Library Exception, version
     18 3.1, as published by the Free Software Foundation.
     19 
     20 You should have received a copy of the GNU General Public License and
     21 a copy of the GCC Runtime Library Exception along with this program;
     22 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
     23 <http://www.gnu.org/licenses/>.  */
     24 
     25 #include "../common/threadasm.S"
     26 
     27 #if defined(__x86_64__)
     28 
     29     .text
     30     .globl CSYM(fiber_switchContext)
     31     .def CSYM(fiber_switchContext)
     32     .scl 2
     33     .type 32
     34     .endef
     35     .align 16
     36 CSYM(fiber_switchContext):
     37     .cfi_startproc
     38     pushq %RBP;
     39     movq %RSP, %RBP;
     40     pushq %RBX;
     41     pushq %R12;
     42     pushq %R13;
     43     pushq %R14;
     44     pushq %R15;
     45     pushq %GS:0;
     46     pushq %GS:8;
     47     pushq %GS:16;
     48 
     49     // store oldp
     50     movq %RSP, (%RCX);
     51     // load newp to begin context switch
     52     movq %RDX, %RSP;
     53 
     54     // load saved state from new stack
     55     popq %GS:16;
     56     popq %GS:8;
     57     popq %GS:0;
     58     popq %R15;
     59     popq %R14;
     60     popq %R13;
     61     popq %R12;
     62     popq %RBX;
     63     popq %RBP;
     64 
     65     // 'return' to complete switch
     66     popq %RCX;
     67     jmp *%RCX;
     68     .cfi_endproc
     69 
     70 #elif defined(_X86_)
     71 
     72     .text
     73     .globl CSYM(fiber_switchContext)
     74     .def CSYM(fiber_switchContext)
     75     .scl 2
     76     .type 32
     77     .endef
     78     .align 16
     79 CSYM(fiber_switchContext):
     80     .cfi_startproc
     81     // Save current stack state.save current stack state
     82     // Standard CDECL prologue.
     83     push %EBP;
     84     mov  %ESP, %EBP;
     85     push %EDI;
     86     push %ESI;
     87     push %EBX;
     88     push %FS:0;
     89     push %FS:4;
     90     push %FS:8;
     91     push %EAX;
     92 
     93     // store oldp again with more accurate address
     94     mov 8(%EBP), %EAX;
     95     mov %ESP, (%EAX);
     96     // load newp to begin context switch
     97     mov 12(%EBP), %ESP;
     98 
     99     // load saved state from new stack
    100     pop %EAX;
    101     pop %FS:8;
    102     pop %FS:4;
    103     pop %FS:0;
    104     pop %EBX;
    105     pop %ESI;
    106     pop %EDI;
    107     pop %EBP;
    108 
    109     // 'return' to complete switch
    110     ret;
    111     .cfi_endproc
    112 
    113 #endif
    114