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Source file test/fixedbugs/issue21655.go

Documentation: test/fixedbugs

  // compile
  
  // Copyright 2017 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  // Make sure assembly offsets don't get too large.
  
  // To trigger issue21655, the index offset needs to be small
  // enough to fit into an int32 (to get rewritten to an ADDQconst)
  // but large enough to overflow an int32 after multiplying by the stride.
  
  package main
  
  func f1(a []int64, i int64) int64 {
  	return a[i+1<<30]
  }
  func f2(a []int32, i int64) int32 {
  	return a[i+1<<30]
  }
  func f3(a []int16, i int64) int16 {
  	return a[i+1<<30]
  }
  func f4(a []int8, i int64) int8 {
  	return a[i+1<<31]
  }
  func f5(a []float64, i int64) float64 {
  	return a[i+1<<30]
  }
  func f6(a []float32, i int64) float32 {
  	return a[i+1<<30]
  }
  
  // Note: Before the fix for issue 21655, f{1,2,5,6} made
  // the compiler crash. f3 silently generated the wrong
  // code, using an offset of -1<<31 instead of 1<<31.
  // (This is due to the assembler accepting offsets
  // like 0x80000000 and silently using them as
  // signed 32 bit offsets.)
  // f4 was ok, but testing it can't hurt.
  

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