1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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7 * published by the Free Software Foundation.
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12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
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24
25 #ifndef SHARE_VM_OPTO_OPTOREG_HPP
26 #define SHARE_VM_OPTO_OPTOREG_HPP
27
28 //------------------------------OptoReg----------------------------------------
29 // We eventually need Registers for the Real World. Registers are essentially
30 // non-SSA names. A Register is represented as a number. Non-regular values
31 // (e.g., Control, Memory, I/O) use the Special register. The actual machine
32 // registers (as described in the ADL file for a machine) start at zero.
33 // Stack-slots (spill locations) start at the nest Chunk past the last machine
34 // register.
35 //
36 // Note that stack spill-slots are treated as a very large register set.
37 // They have all the correct properties for a Register: not aliased (unique
38 // named). There is some simple mapping from a stack-slot register number
39 // to the actual location on the stack; this mapping depends on the calling
40 // conventions and is described in the ADL.
41 //
42 // Note that Name is not enum. C++ standard defines that the range of enum
43 // is the range of smallest bit-field that can represent all enumerators
44 // declared in the enum. The result of assigning a value to enum is undefined
45 // if the value is outside the enumeration's valid range. OptoReg::Name is
46 // typedef'ed as int, because it needs to be able to represent spill-slots.
47 //
48 class OptoReg VALUE_OBJ_CLASS_SPEC {
49
50 friend class C2Compiler;
51 public:
52 typedef int Name;
53 enum {
54 // Chunk 0
55 Physical = AdlcVMDeps::Physical, // Start of physical regs
56 // A few oddballs at the edge of the world
57 Special = -2, // All special (not allocated) values
58 Bad = -1 // Not a register
59 };
60
61 private:
62
63 static const VMReg opto2vm[REG_COUNT];
64 static Name vm2opto[ConcreteRegisterImpl::number_of_registers];
65
66 public:
67
68 // Stack pointer register
69 static OptoReg::Name c_frame_pointer;
70
71
72
73 // Increment a register number. As in:
74 // "for ( OptoReg::Name i; i=Control; i = add(i,1) ) ..."
75 static Name add( Name x, int y ) { return Name(x+y); }
76
77 // (We would like to have an operator+ for RegName, but it is not
78 // a class, so this would be illegal in C++.)
79
80 static void dump( int );
81
82 // Get the stack slot number of an OptoReg::Name
83 static unsigned int reg2stack( OptoReg::Name r) {
84 assert( r >= stack0(), " must be");
85 return r - stack0();
86 }
87
88 // convert a stack slot number into an OptoReg::Name
89 static OptoReg::Name stack2reg( int idx) {
90 return Name(stack0() + idx);
91 }
92
93 static bool is_stack(Name n) {
94 return n >= stack0();
95 }
96
97 static bool is_valid(Name n) {
98 return (n != Bad);
99 }
100
101 static bool is_reg(Name n) {
102 return is_valid(n) && !is_stack(n);
103 }
104
105 static VMReg as_VMReg(OptoReg::Name n) {
106 if (is_reg(n)) {
107 // Must use table, it'd be nice if Bad was indexable...
108 return opto2vm[n];
109 } else {
110 assert(!is_stack(n), "must un warp");
111 return VMRegImpl::Bad();
112 }
113 }
114
115 // Can un-warp a stack slot or convert a register or Bad
116 static VMReg as_VMReg(OptoReg::Name n, int frame_size, int arg_count) {
117 if (is_reg(n)) {
118 // Must use table, it'd be nice if Bad was indexable...
119 return opto2vm[n];
120 } else if (is_stack(n)) {
121 int stack_slot = reg2stack(n);
122 if (stack_slot < arg_count) {
123 return VMRegImpl::stack2reg(stack_slot + frame_size);
124 }
125 return VMRegImpl::stack2reg(stack_slot - arg_count);
126 // return return VMRegImpl::stack2reg(reg2stack(OptoReg::add(n, -arg_count)));
127 } else {
128 return VMRegImpl::Bad();
129 }
130 }
131
132 static OptoReg::Name as_OptoReg(VMReg r) {
133 if (r->is_stack()) {
134 assert(false, "must warp");
135 return stack2reg(r->reg2stack());
136 } else if (r->is_valid()) {
137 // Must use table, it'd be nice if Bad was indexable...
138 return vm2opto[r->value()];
139 } else {
140 return Bad;
141 }
142 }
143
144 static OptoReg::Name stack0() {
145 return VMRegImpl::stack0->value();
146 }
147
148 static const char* regname(OptoReg::Name n) {
149 return as_VMReg(n)->name();
150 }
151
152 };
153
154 //---------------------------OptoRegPair-------------------------------------------
155 // Pairs of 32-bit registers for the allocator.
156 // This is a very similar class to VMRegPair. C2 only interfaces with VMRegPair
157 // via the calling convention code which is shared between the compilers.
158 // Since C2 uses OptoRegs for register allocation it is more efficient to use
159 // VMRegPair internally for nodes that can contain a pair of OptoRegs rather
160 // than use VMRegPair and continually be converting back and forth. So normally
161 // C2 will take in a VMRegPair from the calling convention code and immediately
162 // convert them to an OptoRegPair and stay in the OptoReg world. The only over
163 // conversion between OptoRegs and VMRegs is for debug info and oopMaps. This
164 // is not a high bandwidth spot and so it is not an issue.
165 // Note that onde other consequence of staying in the OptoReg world with OptoRegPairs
166 // is that there are "physical" OptoRegs that are not representable in the VMReg
167 // world, notably flags. [ But by design there is "space" in the VMReg world
168 // for such registers they just may not be concrete ]. So if we were to use VMRegPair
169 // then the VMReg world would have to have a representation for these registers
170 // so that a OptoReg->VMReg->OptoReg would reproduce ther original OptoReg. As it
171 // stands if you convert a flag (condition code) to a VMReg you will get VMRegImpl::Bad
172 // and converting that will return OptoReg::Bad losing the identity of the OptoReg.
173
174 class OptoRegPair {
175 private:
176 short _second;
177 short _first;
178 public:
179 void set_bad ( ) { _second = OptoReg::Bad; _first = OptoReg::Bad; }
180 void set1 ( OptoReg::Name n ) { _second = OptoReg::Bad; _first = n; }
181 void set2 ( OptoReg::Name n ) { _second = n + 1; _first = n; }
182 void set_pair( OptoReg::Name second, OptoReg::Name first ) { _second= second; _first= first; }
183 void set_ptr ( OptoReg::Name ptr ) {
184 #ifdef _LP64
185 _second = ptr+1;
186 #else
187 _second = OptoReg::Bad;
188 #endif
189 _first = ptr;
190 }
191
192 OptoReg::Name second() const { return _second; }
193 OptoReg::Name first() const { return _first; }
194 OptoRegPair(OptoReg::Name second, OptoReg::Name first) { _second = second; _first = first; }
195 OptoRegPair(OptoReg::Name f) { _second = OptoReg::Bad; _first = f; }
196 OptoRegPair() { _second = OptoReg::Bad; _first = OptoReg::Bad; }
197 };
198
199 #endif // SHARE_VM_OPTO_OPTOREG_HPP