asm_ppc64x.h

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // FIXED_FRAME defines the size of the fixed part of a stack frame. A stack
     6  // frame looks like this:
     7  //
     8  // +---------------------+
     9  // | local variable area |
    10  // +---------------------+
    11  // | argument area       |
    12  // +---------------------+ <- R1+FIXED_FRAME
    13  // | fixed area          |
    14  // +---------------------+ <- R1
    15  //
    16  // So a function that sets up a stack frame at all uses as least FIXED_FRAME
    17  // bytes of stack. This mostly affects assembly that calls other functions
    18  // with arguments (the arguments should be stored at FIXED_FRAME+0(R1),
    19  // FIXED_FRAME+8(R1) etc) and some other low-level places.
    20  //
    21  // The reason for using a constant is to make supporting PIC easier (although
    22  // we only support PIC on ppc64le which has a minimum 32 bytes of stack frame,
    23  // and currently always use that much, PIC on ppc64 would need to use 48).
    24  
    25  #define FIXED_FRAME 32
    26
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