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Source file test/opt_branchlikely.go

Documentation: test

  // +build amd64
  // errorcheck -0 -d=ssa/likelyadjust/debug=1,ssa/insert_resched_checks/off
  // rescheduling check insertion is turend off because the inserted conditional branches perturb the errorcheck
  
  // Copyright 2016 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.
  
  // Test that branches have some prediction properties.
  package foo
  
  func f(x, y, z int) int {
  	a := 0
  	for i := 0; i < x; i++ { // ERROR "Branch prediction rule stay in loop"
  		for j := 0; j < y; j++ { // ERROR "Branch prediction rule stay in loop"
  			a += j
  		}
  		for k := 0; k < z; k++ { // ERROR "Branch prediction rule stay in loop"
  			a -= x + y + z
  		}
  	}
  	return a
  }
  
  func g(x, y, z int) int {
  	a := 0
  	if y == 0 { // ERROR "Branch prediction rule default < call"
  		y = g(y, z, x)
  	} else {
  		y++
  	}
  	if y == x { // ERROR "Branch prediction rule default < call"
  		y = g(y, z, x)
  	} else {
  	}
  	if y == 2 { // ERROR "Branch prediction rule default < call"
  		z++
  	} else {
  		y = g(z, x, y)
  	}
  	if y+z == 3 { // ERROR "Branch prediction rule call < exit"
  		println("ha ha")
  	} else {
  		panic("help help help")
  	}
  	if x != 0 { // ERROR "Branch prediction rule default < ret"
  		for i := 0; i < x; i++ { // ERROR "Branch prediction rule stay in loop"
  			if x == 4 { // ERROR "Branch prediction rule stay in loop"
  				return a
  			}
  			for j := 0; j < y; j++ { // ERROR "Branch prediction rule stay in loop"
  				for k := 0; k < z; k++ { // ERROR "Branch prediction rule stay in loop"
  					a -= j * i
  				}
  				a += j
  			}
  		}
  	}
  	return a
  }
  
  func h(x, y, z int) int {
  	a := 0
  	for i := 0; i < x; i++ { // ERROR "Branch prediction rule stay in loop"
  		for j := 0; j < y; j++ { // ERROR "Branch prediction rule stay in loop"
  			a += j
  			if i == j { // ERROR "Branch prediction rule stay in loop"
  				break
  			}
  			a *= j
  		}
  		for k := 0; k < z; k++ { // ERROR "Branch prediction rule stay in loop"
  			a -= k
  			if i == k {
  				continue
  			}
  			a *= k
  		}
  	}
  	if a > 0 { // ERROR "Branch prediction rule default < call"
  		a = g(x, y, z)
  	} else {
  		a = -a
  	}
  	return a
  }
  

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