asm_unix_amd64.s

     1  // Copyright 2026 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  //go:build goexperiment.cgobindings && (darwin || (linux && !android)) && amd64
     6  
     7  #include "go_asm.h"
     8  #include "textflag.h"
     9  #include "abi_amd64.h"
    10  
    11  // callC calls a C function with up to 6 integer/pointer arguments
    12  // in the System V AMD64 ABI and returns its integer/pointer result.
    13  // The function may be variadic: AX is cleared to tell it that no
    14  // arguments are passed in vector registers.
    15  TEXT ·callC<ABIInternal>(SB),NOSPLIT,$0
    16  	// Convert from Go ABIInternal (AX, BX, CX, DI, SI, R8, R9)
    17  	// to System V AMD64 ABI (fn in R11; args in DI, SI, DX, CX, R8, R9).
    18  	MOVQ	AX, R11
    19  	MOVQ	DI, DX
    20  	MOVQ	BX, DI
    21  	MOVQ	CX, AX
    22  	MOVQ	SI, CX
    23  	MOVQ	AX, SI
    24  	// a4 and a5 are already in R8 and R9.
    25  	MOVQ	SP, BX
    26  	ANDQ	$~15, SP
    27  	XORL	AX, AX	// vararg: say "no float args"
    28  	CALL	R11
    29  	MOVQ	BX, SP
    30  	// Restore X15 (the ABIInternal zero register), which is caller-saved
    31  	// in the System V AMD64 ABI. The return value is already in AX.
    32  #ifndef GOAMD64_v3
    33  #ifndef GOAMD64_v4
    34  	XORPS	X15, X15
    35  	CMPB	internal∕cpu·X86+const_offsetX86HasAVX(SB), $1
    36  	JNE	noavx
    37  #endif
    38  #endif
    39  	VXORPS	X15, X15, X15
    40  noavx:
    41  	RET
    42
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