source: src/ResolvExpr/Cost.h@ bdc8591

Last change on this file since bdc8591 was 2908f08, checked in by Andrew Beach <ajbeach@…>, 22 months ago

Most of ResolvExpr was written before the new style standard. Some files updated, focus on headers.
  • Property mode set to 100644
File size: 5.9 KB
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1//
2// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
3//
4// The contents of this file are covered under the licence agreement in the
5// file "LICENCE" distributed with Cforall.
6//
7// Cost.h --
8//
9// Author : Peter Buhr and Aaron Moss
10// Created On : Sun May 17 09:39:50 2015
11// Last Modified By : Peter A. Buhr
12// Last Modified On : Fri Jun 21 11:39:13 2019
13// Update Count : 63
14//
15
16#pragma once
17
18#include <iostream>
19#include <cassert>
20#include <climits>
21
22namespace ResolvExpr {
23
24// To maximize performance and space, the 7 resolution costs are packed into a single 64-bit word. However, the
25// specialization cost is a negative value so a correction is needed is a few places.
26
27class Cost {
28 union {
29 struct {
30 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
31 // Little-endian => first value is low priority and last is high priority.
32 unsigned char padding; ///< unused
33 unsigned char referenceCost; ///< reference conversions
34 unsigned char specCost; ///< Polymorphic type specializations (type assertions), negative cost
35 unsigned char varCost; ///< Count of polymorphic type variables
36 unsigned char signCost; ///< Count of safe sign conversions
37 unsigned char safeCost; ///< Safe (widening) conversions
38 unsigned char polyCost; ///< Count of parameters and return values bound to some poly type
39 unsigned char unsafeCost; ///< Unsafe (narrowing) conversions
40 #else
41 #error Cost BIG_ENDIAN unsupported
42 #endif
43 } v;
44 uint64_t all;
45 };
46 static const unsigned char correctb = 0xff; // byte correction for negative spec cost
47 static const uint64_t correctw = 0x00'00'00'00'00'ff'00'00; //' word correction for negative spec cost
48 public:
49 // Compiler adjusts constants for correct endian.
50 enum : uint64_t {
51 zero = 0x00'00'00'00'00'ff'00'00,
52 infinity = 0xff'ff'ff'ff'ff'00'ff'ff,
53 unsafe = 0x01'00'00'00'00'ff'00'00,
54 poly = 0x00'01'00'00'00'ff'00'00,
55 safe = 0x00'00'01'00'00'ff'00'00,
56 sign = 0x00'00'00'01'00'ff'00'00,
57 var = 0x00'00'00'00'01'ff'00'00,
58 spec = 0x00'00'00'00'00'fe'00'00,
59 reference = 0x00'00'00'00'00'ff'01'00,
60 }; //'
61
62 Cost( uint64_t all ) { Cost::all = all; }
63 Cost( int unsafeCost, int polyCost, int safeCost, int signCost, int varCost, int specCost, int referenceCost ) {
64 // Assume little-endian => first value is low priority and last is high priority.
65 v = {
66 #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
67 (unsigned char)0, // padding
68 (unsigned char)referenceCost, // low priority
69 (unsigned char)(specCost + correctb), // correct for signedness
70 (unsigned char)varCost,
71 (unsigned char)signCost,
72 (unsigned char)safeCost,
73 (unsigned char)polyCost,
74 (unsigned char)unsafeCost, // high priority
75 #else
76 #error Cost BIG_ENDIAN unsupported
77 #endif
78 };
79 }
80
81 int get_unsafeCost() const { return v.unsafeCost; }
82 int get_polyCost() const { return v.polyCost; }
83 int get_safeCost() const { return v.safeCost; }
84 int get_signCost() const { return v.signCost; }
85 int get_varCost() const { return v.varCost; }
86 int get_specCost() const { return -(correctb - v.specCost); }
87 int get_referenceCost() const { return v.referenceCost; }
88
89 friend bool operator==( const Cost, const Cost );
90 friend bool operator!=( const Cost lhs, const Cost rhs );
91 // returns negative for *this < rhs, 0 for *this == rhs, positive for *this > rhs
92 int compare( const Cost rhs ) const {
93 if ( all == infinity ) return 1;
94 if ( rhs.all == infinity ) return -1;
95 return all > rhs.all ? 1 : all == rhs.all ? 0 : -1;
96 }
97 friend bool operator<( const Cost lhs, const Cost rhs );
98
99 friend Cost operator+( const Cost lhs, const Cost rhs );
100
101 Cost operator+=( const Cost rhs ) {
102 if ( all == infinity ) return *this;
103 if ( rhs.all == infinity ) {
104 all = infinity;
105 return *this;
106 }
107 all += rhs.all - correctw; // correct for negative spec cost
108 return *this;
109 }
110
111 Cost incUnsafe( int inc = 1 ) {
112 if ( all != infinity ) { assert( v.unsafeCost + inc <= UCHAR_MAX ); v.unsafeCost += inc; }
113 return *this;
114 }
115
116 Cost incPoly( int inc = 1 ) {
117 if ( all != infinity ) { assert( v.polyCost + inc <= UCHAR_MAX ); v.polyCost += inc; }
118 return *this;
119 }
120
121 Cost incSafe( int inc = 1 ) {
122 if ( all != infinity ) { assert( v.safeCost + inc <= UCHAR_MAX ); v.safeCost += inc; }
123 return *this;
124 }
125
126 Cost incSign( int inc = 1 ) {
127 if ( all != infinity ) { assert( v.signCost + inc <= UCHAR_MAX ); v.signCost += inc; }
128 return *this;
129 }
130
131 Cost incVar( int inc = 1 ) {
132 if ( all != infinity ) { assert( v.varCost + inc <= UCHAR_MAX ); v.varCost += inc; }
133 return *this;
134 }
135
136 Cost decSpec( int dec = 1 ) {
137 if ( all != infinity ) { assert( v.specCost - dec >= 0 ); v.specCost -= dec; }
138 return *this;
139 }
140
141 Cost incReference( int inc = 1 ) {
142 if ( all != infinity ) { assert( v.referenceCost + inc <= UCHAR_MAX ); v.referenceCost += inc; }
143 return *this;
144 }
145
146 friend std::ostream & operator<<( std::ostream & os, const Cost cost );
147};
148
149inline bool operator==( const Cost lhs, const Cost rhs ) {
150 return lhs.all == rhs.all;
151}
152
153inline bool operator!=( const Cost lhs, const Cost rhs ) {
154 return !( lhs.all == rhs.all );
155}
156
157inline bool operator<( const Cost lhs, const Cost rhs ) {
158 if ( lhs.all == Cost::infinity ) return false;
159 if ( rhs.all == Cost::infinity ) return true;
160 return lhs.all < rhs.all;
161}
162
163inline Cost operator+( const Cost lhs, const Cost rhs ) {
164 if ( lhs.all == Cost::infinity || rhs.all == Cost::infinity ) return Cost{ Cost::infinity };
165 return Cost{ lhs.all + rhs.all - Cost::correctw }; // correct for negative spec cost
166}
167
168inline std::ostream & operator<<( std::ostream & os, const Cost cost ) {
169 return os << "( " << cost.get_unsafeCost() << ", " << cost.get_polyCost() << ", " << cost.get_safeCost()
170 << ", " << cost.get_signCost() << ", " << cost.get_varCost() << ", " << cost.get_specCost()
171 << ", " << cost.get_referenceCost() << " )";
172}
173
174} // namespace ResolvExpr
175
176// Local Variables: //
177// tab-width: 4 //
178// mode: c++ //
179// compile-command: "make install" //
180// End: //
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