notinheap3.go

     1  // errorcheck -+ -0 -l -d=wb
     2  
     3  // Copyright 2016 The Go Authors. All rights reserved.
     4  // Use of this source code is governed by a BSD-style
     5  // license that can be found in the LICENSE file.
     6  
     7  // Test write barrier elimination for notinheap.
     8  
     9  //go:build cgo
    10  
    11  package p
    12  
    13  import "runtime/cgo"
    14  
    15  type t1 struct {
    16  	x *nih
    17  	s []nih
    18  	y [1024]byte // Prevent write decomposition
    19  }
    20  
    21  type t2 struct {
    22  	x *ih
    23  	s []ih
    24  	y [1024]byte
    25  }
    26  
    27  type nih struct {
    28  	_ cgo.Incomplete
    29  	x uintptr
    30  }
    31  
    32  type ih struct { // In-heap type
    33  	x uintptr
    34  }
    35  
    36  var (
    37  	v1 t1
    38  	v2 t2
    39  
    40  	v1s []t1
    41  	v2s []t2
    42  )
    43  
    44  func f() {
    45  	// Test direct writes
    46  	v1.x = nil        // no barrier
    47  	v2.x = nil        // ERROR "write barrier"
    48  	v1.s = []nih(nil) // no barrier
    49  	v2.s = []ih(nil)  // ERROR "write barrier"
    50  }
    51  
    52  func g() {
    53  	// Test aggregate writes
    54  	v1 = t1{x: nil} // no barrier
    55  	v2 = t2{x: nil} // ERROR "write barrier"
    56  }
    57  
    58  func h() {
    59  	// Test copies and appends.
    60  	copy(v1s, v1s[1:])      // no barrier
    61  	copy(v2s, v2s[1:])      // ERROR "write barrier"
    62  	_ = append(v1s, v1s...) // no barrier
    63  	_ = append(v2s, v2s...) // ERROR "write barrier"
    64  }
    65  
    66  // Slice clearing
    67  
    68  var (
    69  	sliceIH  []*ih
    70  	sliceNIH []*nih
    71  )
    72  
    73  func sliceClear() {
    74  	for i := range sliceIH {
    75  		sliceIH[i] = nil // ERROR "write barrier"
    76  	}
    77  	for i := range sliceNIH {
    78  		sliceNIH[i] = nil // no barrier
    79  	}
    80  }
    81
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