github.com/slayercat/go@v0.0.0-20170428012452-c51559813f61/src/runtime/cgo/asm_arm.s (about)

     1  // Copyright 2012 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  #include "textflag.h"
     6  
     7  // Called by C code generated by cmd/cgo.
     8  // func crosscall2(fn func(a unsafe.Pointer, n int32, ctxt uintptr), a unsafe.Pointer, n int32, ctxt uintptr)
     9  // Saves C callee-saved registers and calls fn with three arguments.
    10  TEXT crosscall2(SB),NOSPLIT,$-4
    11  	/* 
    12  	 * We still need to save all callee save register as before, and then
    13  	 *  push 3 args for fn (R1, R2, R3).
    14  	 * Also note that at procedure entry in gc world, 4(R13) will be the
    15  	 *  first arg, so we must push another dummy reg (R0) for 0(R13).
    16  	 *  Additionally, runtime·load_g will clobber R0, so we need to save R0
    17  	 *  nevertheless.
    18  	 */
    19  	SUB	$(8*9), R13 // Reserve space for the floating point registers.
    20  	MOVM.WP	[R0, R1, R2, R3, R4, R5, R6, R7, R8, R9, g, R11, R12, R14], (R13)
    21  
    22  	// Skip floating point registers on GOARM < 6.
    23  	MOVB    runtime·goarm(SB), R11
    24  	CMP $6, R11
    25  	BLT skipfpsave
    26  	MOVD	F8, (14*4+8*1)(R13)
    27  	MOVD	F9, (14*4+8*2)(R13)
    28  	MOVD	F10, (14*4+8*3)(R13)
    29  	MOVD	F11, (14*4+8*4)(R13)
    30  	MOVD	F12, (14*4+8*5)(R13)
    31  	MOVD	F13, (14*4+8*6)(R13)
    32  	MOVD	F14, (14*4+8*7)(R13)
    33  	MOVD	F15, (14*4+8*8)(R13)
    34  
    35  skipfpsave:
    36  	BL	runtime·load_g(SB)
    37  	MOVW	R15, R14 // R15 is PC.
    38  	MOVW	0(R13), R15
    39  
    40  	MOVB    runtime·goarm(SB), R11
    41  	CMP $6, R11
    42  	BLT skipfprest
    43  	MOVD	(14*4+8*1)(R13), F8
    44  	MOVD	(14*4+8*2)(R13), F9
    45  	MOVD	(14*4+8*3)(R13), F10
    46  	MOVD	(14*4+8*4)(R13), F11
    47  	MOVD	(14*4+8*5)(R13), F12
    48  	MOVD	(14*4+8*6)(R13), F13
    49  	MOVD	(14*4+8*7)(R13), F14
    50  	MOVD	(14*4+8*8)(R13), F15
    51  
    52  skipfprest:
    53  	MOVM.IAW	(R13), [R0, R1, R2, R3, R4, R5, R6, R7, R8, R9, g, R11, R12, R14]
    54  	ADD	$(8*9), R13
    55  	MOVW	R14, R15