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#define FUNCDATA_ArgInfo 5
		21
		22// Pseudo-assembly statements.
		23
		24// GO_ARGS, GO_RESULTS_INITIALIZED, and NO_LOCAL_POINTERS are macros
		25// that communicate to the runtime information about the location and liveness
		26// of pointers in an assembly function's arguments, results, and stack frame.
		27// This communication is only required in assembly functions that make calls
		28// to other functions that might be preempted or grow the stack.
		29// NOSPLIT functions that make no calls do not need to use these macros.
		30
		31// GO_ARGS indicates that the Go prototype for this assembly function
		32// defines the pointer map for the function's arguments.
		33// GO_ARGS should be the first instruction in a function that uses it.
		34// It can be omitted if there are no arguments at all.
		35// GO_ARGS is inserted implicitly by the linker for any function whose
		36// name starts with a middle-dot and that also has a Go prototype; it
		37// is therefore usually not necessary to write explicitly.
		38#define GO_ARGS	FUNCDATA $FUNCDATA_ArgsPointerMaps, go_args_stackmap(SB)
		39
		40// GO_RESULTS_INITIALIZED indicates that the assembly function
		41// has initialized the stack space for its results and that those results
		42// should be considered live for the remainder of the function.
		43#define GO_RESULTS_INITIALIZED	PCDATA $PCDATA_StackMapIndex, $1
		44
		45// NO_LOCAL_POINTERS indicates that the assembly function stores
		46// no pointers to heap objects in its local stack variables.
		47#define NO_LOCAL_POINTERS	FUNCDATA $FUNCDATA_LocalsPointerMaps, runtime·no_pointers_stackmap(SB)
		48
		49// ArgsSizeUnknown is set in Func.argsize to mark all functions
		50// whose argument size is unknown (C vararg functions, and
		51// assembly code without an explicit specification).
		52// This value is generated by the compiler, assembler, or linker.
		53#define ArgsSizeUnknown 0x80000000
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