github.com/filosottile/go@v0.0.0-20170906193555-dbed9972d994/test/mergemul.go (about)

     1  // runoutput
     2  
     3  // Copyright 2017 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  package main
     8  
     9  import "fmt"
    10  
    11  // Check that expressions like (c*n + d*(n+k)) get correctly merged by
    12  // the compiler into (c+d)*n + d*k (with c+d and d*k computed at
    13  // compile time).
    14  //
    15  // The merging is performed by a combination of the multiplication
    16  // merge rules
    17  //  (c*n + d*n) -> (c+d)*n
    18  // and the distributive multiplication rules
    19  //  c * (d+x)  ->  c*d + c*x
    20  
    21  // Generate a MergeTest that looks like this:
    22  //
    23  //   a8, b8 = m1*n8 + m2*(n8+k), (m1+m2)*n8 + m2*k
    24  //   if a8 != b8 {
    25  // 	   // print error msg and panic
    26  //   }
    27  func makeMergeTest(m1, m2, k int, size string) string {
    28  
    29  	model := "    a" + size + ", b" + size
    30  	model += fmt.Sprintf(" = %%d*n%s + %%d*(n%s+%%d), (%%d+%%d)*n%s + (%%d*%%d)", size, size, size)
    31  
    32  	test := fmt.Sprintf(model, m1, m2, k, m1, m2, m2, k)
    33  	test += fmt.Sprintf(`
    34      if a%s != b%s {
    35          fmt.Printf("MergeTest(%d, %d, %d, %s) failed\n")
    36          fmt.Printf("%%d != %%d\n", a%s, b%s)
    37          panic("FAIL")
    38      }
    39  `, size, size, m1, m2, k, size, size, size)
    40  	return test + "\n"
    41  }
    42  
    43  func makeAllSizes(m1, m2, k int) string {
    44  	var tests string
    45  	tests += makeMergeTest(m1, m2, k, "8")
    46  	tests += makeMergeTest(m1, m2, k, "16")
    47  	tests += makeMergeTest(m1, m2, k, "32")
    48  	tests += makeMergeTest(m1, m2, k, "64")
    49  	tests += "\n"
    50  	return tests
    51  }
    52  
    53  func main() {
    54  	fmt.Println(`package main
    55  
    56  import "fmt"
    57  
    58  var n8 int8 = 42
    59  var n16 int16 = 42
    60  var n32 int32 = 42
    61  var n64 int64 = 42
    62  
    63  func main() {
    64      var a8, b8 int8
    65      var a16, b16 int16
    66      var a32, b32 int32
    67      var a64, b64 int64
    68  `)
    69  
    70  	fmt.Println(makeAllSizes(03, 05, 0)) // 3*n + 5*n
    71  	fmt.Println(makeAllSizes(17, 33, 0))
    72  	fmt.Println(makeAllSizes(80, 45, 0))
    73  	fmt.Println(makeAllSizes(32, 64, 0))
    74  
    75  	fmt.Println(makeAllSizes(7, 11, +1)) // 7*n + 11*(n+1)
    76  	fmt.Println(makeAllSizes(9, 13, +2))
    77  	fmt.Println(makeAllSizes(11, 16, -1))
    78  	fmt.Println(makeAllSizes(17, 9, -2))
    79  
    80  	fmt.Println("}")
    81  }