phi_test.go

     1  // Copyright 2016 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package main
     6  
     7  // Test to make sure spills of cast-shortened values
     8  // don't end up spilling the pre-shortened size instead
     9  // of the post-shortened size.
    10  
    11  import (
    12  	"runtime"
    13  	"testing"
    14  )
    15  
    16  var data1 [26]int32
    17  var data2 [26]int64
    18  
    19  func init() {
    20  	for i := 0; i < 26; i++ {
    21  		// If we spill all 8 bytes of this datum, the 1 in the high-order 4 bytes
    22  		// will overwrite some other variable in the stack frame.
    23  		data2[i] = 0x100000000
    24  	}
    25  }
    26  
    27  func foo() int32 {
    28  	var a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z int32
    29  	if always {
    30  		a = data1[0]
    31  		b = data1[1]
    32  		c = data1[2]
    33  		d = data1[3]
    34  		e = data1[4]
    35  		f = data1[5]
    36  		g = data1[6]
    37  		h = data1[7]
    38  		i = data1[8]
    39  		j = data1[9]
    40  		k = data1[10]
    41  		l = data1[11]
    42  		m = data1[12]
    43  		n = data1[13]
    44  		o = data1[14]
    45  		p = data1[15]
    46  		q = data1[16]
    47  		r = data1[17]
    48  		s = data1[18]
    49  		t = data1[19]
    50  		u = data1[20]
    51  		v = data1[21]
    52  		w = data1[22]
    53  		x = data1[23]
    54  		y = data1[24]
    55  		z = data1[25]
    56  	} else {
    57  		a = int32(data2[0])
    58  		b = int32(data2[1])
    59  		c = int32(data2[2])
    60  		d = int32(data2[3])
    61  		e = int32(data2[4])
    62  		f = int32(data2[5])
    63  		g = int32(data2[6])
    64  		h = int32(data2[7])
    65  		i = int32(data2[8])
    66  		j = int32(data2[9])
    67  		k = int32(data2[10])
    68  		l = int32(data2[11])
    69  		m = int32(data2[12])
    70  		n = int32(data2[13])
    71  		o = int32(data2[14])
    72  		p = int32(data2[15])
    73  		q = int32(data2[16])
    74  		r = int32(data2[17])
    75  		s = int32(data2[18])
    76  		t = int32(data2[19])
    77  		u = int32(data2[20])
    78  		v = int32(data2[21])
    79  		w = int32(data2[22])
    80  		x = int32(data2[23])
    81  		y = int32(data2[24])
    82  		z = int32(data2[25])
    83  	}
    84  	// Lots of phis of the form phi(int32,int64) of type int32 happen here.
    85  	// Some will be stack phis. For those stack phis, make sure the spill
    86  	// of the second argument uses the phi's width (4 bytes), not its width
    87  	// (8 bytes).  Otherwise, a random stack slot gets clobbered.
    88  
    89  	runtime.Gosched()
    90  	return a + b + c + d + e + f + g + h + i + j + k + l + m + n + o + p + q + r + s + t + u + v + w + x + y + z
    91  }
    92  
    93  func TestPhi(t *testing.T) {
    94  	want := int32(0)
    95  	got := foo()
    96  	if got != want {
    97  		t.Fatalf("want %d, got %d\n", want, got)
    98  	}
    99  }
   100
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