1 /*
2 * Copyright (c) 2006, 2007, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
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23 */
24
25 //------------------------------OptoReg----------------------------------------
26 // We eventually need Registers for the Real World. Registers are essentially
27 // non-SSA names. A Register is represented as a number. Non-regular values
28 // (e.g., Control, Memory, I/O) use the Special register. The actual machine
29 // registers (as described in the ADL file for a machine) start at zero.
30 // Stack-slots (spill locations) start at the nest Chunk past the last machine
31 // register.
32 //
33 // Note that stack spill-slots are treated as a very large register set.
34 // They have all the correct properties for a Register: not aliased (unique
35 // named). There is some simple mapping from a stack-slot register number
36 // to the actual location on the stack; this mapping depends on the calling
37 // conventions and is described in the ADL.
38 //
39 // Note that Name is not enum. C++ standard defines that the range of enum
40 // is the range of smallest bit-field that can represent all enumerators
41 // declared in the enum. The result of assigning a value to enum is undefined
42 // if the value is outside the enumeration's valid range. OptoReg::Name is
43 // typedef'ed as int, because it needs to be able to represent spill-slots.
44 //
45 class OptoReg VALUE_OBJ_CLASS_SPEC {
46
47 friend class C2Compiler;
48 public:
49 typedef int Name;
50 enum {
51 // Chunk 0
52 Physical = AdlcVMDeps::Physical, // Start of physical regs
53 // A few oddballs at the edge of the world
54 Special = -2, // All special (not allocated) values
55 Bad = -1 // Not a register
56 };
57
58 private:
59
60 static const VMReg opto2vm[REG_COUNT];
61 static Name vm2opto[ConcreteRegisterImpl::number_of_registers];
62
63 public:
64
65 // Stack pointer register
66 static OptoReg::Name c_frame_pointer;
67
68
69
70 // Increment a register number. As in:
71 // "for ( OptoReg::Name i; i=Control; i = add(i,1) ) ..."
72 static Name add( Name x, int y ) { return Name(x+y); }
73
74 // (We would like to have an operator+ for RegName, but it is not
75 // a class, so this would be illegal in C++.)
76
77 static void dump( int );
78
79 // Get the stack slot number of an OptoReg::Name
80 static unsigned int reg2stack( OptoReg::Name r) {
81 assert( r >= stack0(), " must be");
82 return r - stack0();
83 }
84
85 // convert a stack slot number into an OptoReg::Name
86 static OptoReg::Name stack2reg( int idx) {
87 return Name(stack0() + idx);
88 }
89
90 static bool is_stack(Name n) {
91 return n >= stack0();
92 }
93
94 static bool is_valid(Name n) {
95 return (n != Bad);
96 }
97
98 static bool is_reg(Name n) {
99 return is_valid(n) && !is_stack(n);
100 }
101
102 static VMReg as_VMReg(OptoReg::Name n) {
103 if (is_reg(n)) {
104 // Must use table, it'd be nice if Bad was indexable...
105 return opto2vm[n];
106 } else {
107 assert(!is_stack(n), "must un warp");
108 return VMRegImpl::Bad();
109 }
110 }
111
112 // Can un-warp a stack slot or convert a register or Bad
113 static VMReg as_VMReg(OptoReg::Name n, int frame_size, int arg_count) {
114 if (is_reg(n)) {
115 // Must use table, it'd be nice if Bad was indexable...
116 return opto2vm[n];
117 } else if (is_stack(n)) {
118 int stack_slot = reg2stack(n);
119 if (stack_slot < arg_count) {
120 return VMRegImpl::stack2reg(stack_slot + frame_size);
121 }
122 return VMRegImpl::stack2reg(stack_slot - arg_count);
123 // return return VMRegImpl::stack2reg(reg2stack(OptoReg::add(n, -arg_count)));
124 } else {
125 return VMRegImpl::Bad();
126 }
127 }
128
129 static OptoReg::Name as_OptoReg(VMReg r) {
130 if (r->is_stack()) {
131 assert(false, "must warp");
132 return stack2reg(r->reg2stack());
133 } else if (r->is_valid()) {
134 // Must use table, it'd be nice if Bad was indexable...
135 return vm2opto[r->value()];
136 } else {
137 return Bad;
138 }
139 }
140
141 static OptoReg::Name stack0() {
142 return VMRegImpl::stack0->value();
143 }
144
145 static const char* regname(OptoReg::Name n) {
146 return as_VMReg(n)->name();
147 }
148
149 };
150
151 //---------------------------OptoRegPair-------------------------------------------
152 // Pairs of 32-bit registers for the allocator.
153 // This is a very similar class to VMRegPair. C2 only interfaces with VMRegPair
154 // via the calling convention code which is shared between the compilers.
155 // Since C2 uses OptoRegs for register allocation it is more efficient to use
156 // VMRegPair internally for nodes that can contain a pair of OptoRegs rather
157 // than use VMRegPair and continually be converting back and forth. So normally
158 // C2 will take in a VMRegPair from the calling convention code and immediately
159 // convert them to an OptoRegPair and stay in the OptoReg world. The only over
160 // conversion between OptoRegs and VMRegs is for debug info and oopMaps. This
161 // is not a high bandwidth spot and so it is not an issue.
162 // Note that onde other consequence of staying in the OptoReg world with OptoRegPairs
163 // is that there are "physical" OptoRegs that are not representable in the VMReg
164 // world, notably flags. [ But by design there is "space" in the VMReg world
165 // for such registers they just may not be concrete ]. So if we were to use VMRegPair
166 // then the VMReg world would have to have a representation for these registers
167 // so that a OptoReg->VMReg->OptoReg would reproduce ther original OptoReg. As it
168 // stands if you convert a flag (condition code) to a VMReg you will get VMRegImpl::Bad
169 // and converting that will return OptoReg::Bad losing the identity of the OptoReg.
170
171 class OptoRegPair {
172 private:
173 short _second;
174 short _first;
175 public:
176 void set_bad ( ) { _second = OptoReg::Bad; _first = OptoReg::Bad; }
177 void set1 ( OptoReg::Name n ) { _second = OptoReg::Bad; _first = n; }
178 void set2 ( OptoReg::Name n ) { _second = n + 1; _first = n; }
179 void set_pair( OptoReg::Name second, OptoReg::Name first ) { _second= second; _first= first; }
180 void set_ptr ( OptoReg::Name ptr ) {
181 #ifdef _LP64
182 _second = ptr+1;
183 #else
184 _second = OptoReg::Bad;
185 #endif
186 _first = ptr;
187 }
188
189 OptoReg::Name second() const { return _second; }
190 OptoReg::Name first() const { return _first; }
191 OptoRegPair(OptoReg::Name second, OptoReg::Name first) { _second = second; _first = first; }
192 OptoRegPair(OptoReg::Name f) { _second = OptoReg::Bad; _first = f; }
193 OptoRegPair() { _second = OptoReg::Bad; _first = OptoReg::Bad; }
194 };