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Text file src/runtime/funcdata.h

Documentation: runtime

     1  // Copyright 2013 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  // This file defines the IDs for PCDATA and FUNCDATA instructions
     6  // in Go binaries. It is included by assembly sources, so it must
     7  // be written using #defines.
     8  //
     9  // These must agree with symtab.go and ../cmd/internal/objabi/funcdata.go.
    10  
    11  #define PCDATA_UnsafePoint 0
    12  #define PCDATA_StackMapIndex 1
    13  #define PCDATA_InlTreeIndex 2
    14  
    15  #define FUNCDATA_ArgsPointerMaps 0 /* garbage collector blocks */
    16  #define FUNCDATA_LocalsPointerMaps 1
    17  #define FUNCDATA_StackObjects 2
    18  #define FUNCDATA_InlTree 3
    19  #define FUNCDATA_OpenCodedDeferInfo 4 /* info for func with open-coded defers */
    20  
    21  // Pseudo-assembly statements.
    22  
    23  // GO_ARGS, GO_RESULTS_INITIALIZED, and NO_LOCAL_POINTERS are macros
    24  // that communicate to the runtime information about the location and liveness
    25  // of pointers in an assembly function's arguments, results, and stack frame.
    26  // This communication is only required in assembly functions that make calls
    27  // to other functions that might be preempted or grow the stack.
    28  // NOSPLIT functions that make no calls do not need to use these macros.
    29  
    30  // GO_ARGS indicates that the Go prototype for this assembly function
    31  // defines the pointer map for the function's arguments.
    32  // GO_ARGS should be the first instruction in a function that uses it.
    33  // It can be omitted if there are no arguments at all.
    34  // GO_ARGS is inserted implicitly by the linker for any function whose
    35  // name starts with a middle-dot and that also has a Go prototype; it
    36  // is therefore usually not necessary to write explicitly.
    37  #define GO_ARGS	FUNCDATA $FUNCDATA_ArgsPointerMaps, go_args_stackmap(SB)
    38  
    39  // GO_RESULTS_INITIALIZED indicates that the assembly function
    40  // has initialized the stack space for its results and that those results
    41  // should be considered live for the remainder of the function.
    42  #define GO_RESULTS_INITIALIZED	PCDATA $PCDATA_StackMapIndex, $1
    43  
    44  // NO_LOCAL_POINTERS indicates that the assembly function stores
    45  // no pointers to heap objects in its local stack variables.
    46  #define NO_LOCAL_POINTERS	FUNCDATA $FUNCDATA_LocalsPointerMaps, runtime┬Ěno_pointers_stackmap(SB)
    47  
    48  // ArgsSizeUnknown is set in Func.argsize to mark all functions
    49  // whose argument size is unknown (C vararg functions, and
    50  // assembly code without an explicit specification).
    51  // This value is generated by the compiler, assembler, or linker.
    52  #define ArgsSizeUnknown 0x80000000
    53  

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