part_live_2.go

     1  // run
     2  
     3  // Copyright 2021 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  // A test for partial liveness / partial spilling / compiler-induced GC failure
     8  
     9  package main
    10  
    11  import "runtime"
    12  import "unsafe"
    13  
    14  //go:registerparams
    15  func F(s []int) {
    16  	for i, x := range s {
    17  		G(i, x)
    18  	}
    19  	GC()
    20  	H(&s[0]) // It's possible that this will make the spill redundant, but there's a bug in spill slot allocation.
    21  	G(len(s), cap(s))
    22  	GC()
    23  }
    24  
    25  //go:noinline
    26  //go:registerparams
    27  func G(int, int) {}
    28  
    29  //go:noinline
    30  //go:registerparams
    31  func H(*int) {}
    32  
    33  //go:registerparams
    34  func GC() { runtime.GC(); runtime.GC() }
    35  
    36  func main() {
    37  	s := make([]int, 3)
    38  	escape(s)
    39  	p := int(uintptr(unsafe.Pointer(&s[2])) + 42) // likely point to unallocated memory
    40  	poison([3]int{p, p, p})
    41  	F(s)
    42  }
    43  
    44  //go:noinline
    45  //go:registerparams
    46  func poison([3]int) {}
    47  
    48  //go:noinline
    49  //go:registerparams
    50  func escape(s []int) {
    51  	g = s
    52  }
    53  var g []int
    54
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