1 /*
2 * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
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).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_ASM_ASSEMBLER_HPP
26 #define SHARE_VM_ASM_ASSEMBLER_HPP
27
28 #include "asm/codeBuffer.hpp"
29 #include "asm/register.hpp"
30 #include "code/oopRecorder.hpp"
31 #include "code/relocInfo.hpp"
32 #include "memory/allocation.hpp"
33 #include "runtime/vm_version.hpp"
34 #include "utilities/debug.hpp"
35 #include "utilities/growableArray.hpp"
36 #include "utilities/macros.hpp"
37
38 // This file contains platform-independent assembler declarations.
39
40 class MacroAssembler;
41 class AbstractAssembler;
42 class Label;
43
44 /**
45 * Labels represent destinations for control transfer instructions. Such
46 * instructions can accept a Label as their target argument. A Label is
47 * bound to the current location in the code stream by calling the
48 * MacroAssembler's 'bind' method, which in turn calls the Label's 'bind'
49 * method. A Label may be referenced by an instruction before it's bound
50 * (i.e., 'forward referenced'). 'bind' stores the current code offset
51 * in the Label object.
52 *
53 * If an instruction references a bound Label, the offset field(s) within
54 * the instruction are immediately filled in based on the Label's code
55 * offset. If an instruction references an unbound label, that
56 * instruction is put on a list of instructions that must be patched
57 * (i.e., 'resolved') when the Label is bound.
58 *
59 * 'bind' will call the platform-specific 'patch_instruction' method to
60 * fill in the offset field(s) for each unresolved instruction (if there
61 * are any). 'patch_instruction' lives in one of the
62 * cpu/<arch>/vm/assembler_<arch>* files.
63 *
64 * Instead of using a linked list of unresolved instructions, a Label has
65 * an array of unresolved instruction code offsets. _patch_index
66 * contains the total number of forward references. If the Label's array
67 * overflows (i.e., _patch_index grows larger than the array size), a
68 * GrowableArray is allocated to hold the remaining offsets. (The cache
69 * size is 4 for now, which handles over 99.5% of the cases)
70 *
71 * Labels may only be used within a single CodeSection. If you need
72 * to create references between code sections, use explicit relocations.
73 */
74 class Label VALUE_OBJ_CLASS_SPEC {
75 private:
76 enum { PatchCacheSize = 4 };
77
78 // _loc encodes both the binding state (via its sign)
79 // and the binding locator (via its value) of a label.
80 //
81 // _loc >= 0 bound label, loc() encodes the target (jump) position
82 // _loc == -1 unbound label
83 int _loc;
84
85 // References to instructions that jump to this unresolved label.
86 // These instructions need to be patched when the label is bound
87 // using the platform-specific patchInstruction() method.
88 //
89 // To avoid having to allocate from the C-heap each time, we provide
90 // a local cache and use the overflow only if we exceed the local cache
91 int _patches[PatchCacheSize];
92 int _patch_index;
93 GrowableArray<int>* _patch_overflow;
94
95 Label(const Label&) { ShouldNotReachHere(); }
96
97 public:
98
99 /**
100 * After binding, be sure 'patch_instructions' is called later to link
101 */
102 void bind_loc(int loc) {
103 assert(loc >= 0, "illegal locator");
104 assert(_loc == -1, "already bound");
105 _loc = loc;
106 }
107 void bind_loc(int pos, int sect) { bind_loc(CodeBuffer::locator(pos, sect)); }
108
109 #ifndef PRODUCT
110 // Iterates over all unresolved instructions for printing
111 void print_instructions(MacroAssembler* masm) const;
112 #endif // PRODUCT
113
114 /**
115 * Returns the position of the the Label in the code buffer
116 * The position is a 'locator', which encodes both offset and section.
117 */
118 int loc() const {
119 assert(_loc >= 0, "unbound label");
120 return _loc;
121 }
122 int loc_pos() const { return CodeBuffer::locator_pos(loc()); }
123 int loc_sect() const { return CodeBuffer::locator_sect(loc()); }
124
125 bool is_bound() const { return _loc >= 0; }
126 bool is_unbound() const { return _loc == -1 && _patch_index > 0; }
127 bool is_unused() const { return _loc == -1 && _patch_index == 0; }
128
129 /**
130 * Adds a reference to an unresolved displacement instruction to
131 * this unbound label
132 *
133 * @param cb the code buffer being patched
134 * @param branch_loc the locator of the branch instruction in the code buffer
135 */
136 void add_patch_at(CodeBuffer* cb, int branch_loc);
137
138 /**
139 * Iterate over the list of patches, resolving the instructions
140 * Call patch_instruction on each 'branch_loc' value
141 */
142 void patch_instructions(MacroAssembler* masm);
143
144 void init() {
145 _loc = -1;
146 _patch_index = 0;
147 _patch_overflow = NULL;
148 }
149
150 Label() {
151 init();
152 }
153 };
154
155 // A union type for code which has to assemble both constant and
156 // non-constant operands, when the distinction cannot be made
157 // statically.
158 class RegisterOrConstant VALUE_OBJ_CLASS_SPEC {
159 private:
160 Register _r;
161 intptr_t _c;
162
163 public:
164 RegisterOrConstant(): _r(noreg), _c(0) {}
165 RegisterOrConstant(Register r): _r(r), _c(0) {}
166 RegisterOrConstant(intptr_t c): _r(noreg), _c(c) {}
167
168 Register as_register() const { assert(is_register(),""); return _r; }
169 intptr_t as_constant() const { assert(is_constant(),""); return _c; }
170
171 Register register_or_noreg() const { return _r; }
172 intptr_t constant_or_zero() const { return _c; }
173
174 bool is_register() const { return _r != noreg; }
175 bool is_constant() const { return _r == noreg; }
176 };
177
178 // The Abstract Assembler: Pure assembler doing NO optimizations on the
179 // instruction level; i.e., what you write is what you get.
180 // The Assembler is generating code into a CodeBuffer.
181 class AbstractAssembler : public ResourceObj {
182 friend class Label;
183
184 protected:
185 CodeSection* _code_section; // section within the code buffer
186 OopRecorder* _oop_recorder; // support for relocInfo::oop_type
187
188 public:
189 // Code emission & accessing
190 address addr_at(int pos) const { return code_section()->start() + pos; }
191
192 protected:
193 // This routine is called with a label is used for an address.
194 // Labels and displacements truck in offsets, but target must return a PC.
195 address target(Label& L) { return code_section()->target(L, pc()); }
196
197 bool is8bit(int x) const { return -0x80 <= x && x < 0x80; }
198 bool isByte(int x) const { return 0 <= x && x < 0x100; }
199 bool isShiftCount(int x) const { return 0 <= x && x < 32; }
200
201 // Instruction boundaries (required when emitting relocatable values).
202 class InstructionMark: public StackObj {
203 private:
204 AbstractAssembler* _assm;
205
206 public:
207 InstructionMark(AbstractAssembler* assm) : _assm(assm) {
208 assert(assm->inst_mark() == NULL, "overlapping instructions");
209 _assm->set_inst_mark();
210 }
211 ~InstructionMark() {
212 _assm->clear_inst_mark();
213 }
214 };
215 friend class InstructionMark;
216 #ifdef ASSERT
217 // Make it return true on platforms which need to verify
218 // instruction boundaries for some operations.
219 static bool pd_check_instruction_mark();
220
221 // Add delta to short branch distance to verify that it still fit into imm8.
222 int _short_branch_delta;
223
224 int short_branch_delta() const { return _short_branch_delta; }
225 void set_short_branch_delta() { _short_branch_delta = 32; }
226 void clear_short_branch_delta() { _short_branch_delta = 0; }
227
228 class ShortBranchVerifier: public StackObj {
229 private:
230 AbstractAssembler* _assm;
231
232 public:
233 ShortBranchVerifier(AbstractAssembler* assm) : _assm(assm) {
234 assert(assm->short_branch_delta() == 0, "overlapping instructions");
235 _assm->set_short_branch_delta();
236 }
237 ~ShortBranchVerifier() {
238 _assm->clear_short_branch_delta();
239 }
240 };
241 #else
242 // Dummy in product.
243 class ShortBranchVerifier: public StackObj {
244 public:
245 ShortBranchVerifier(AbstractAssembler* assm) {}
246 };
247 #endif
248
249 public:
250
251 // Creation
252 AbstractAssembler(CodeBuffer* code);
253
254 // ensure buf contains all code (call this before using/copying the code)
255 void flush();
256
257 void emit_int8( int8_t x) { code_section()->emit_int8( x); }
258 void emit_int16( int16_t x) { code_section()->emit_int16( x); }
259 void emit_int32( int32_t x) { code_section()->emit_int32( x); }
260 void emit_int64( int64_t x) { code_section()->emit_int64( x); }
261
262 void emit_float( jfloat x) { code_section()->emit_float( x); }
263 void emit_double( jdouble x) { code_section()->emit_double( x); }
264 void emit_address(address x) { code_section()->emit_address(x); }
265
266 // min and max values for signed immediate ranges
267 static int min_simm(int nbits) { return -(intptr_t(1) << (nbits - 1)) ; }
268 static int max_simm(int nbits) { return (intptr_t(1) << (nbits - 1)) - 1; }
269
270 // Define some:
271 static int min_simm10() { return min_simm(10); }
272 static int min_simm13() { return min_simm(13); }
273 static int min_simm16() { return min_simm(16); }
274
275 // Test if x is within signed immediate range for nbits
276 static bool is_simm(intptr_t x, int nbits) { return min_simm(nbits) <= x && x <= max_simm(nbits); }
277
278 // Define some:
279 static bool is_simm5( intptr_t x) { return is_simm(x, 5 ); }
280 static bool is_simm8( intptr_t x) { return is_simm(x, 8 ); }
281 static bool is_simm10(intptr_t x) { return is_simm(x, 10); }
282 static bool is_simm11(intptr_t x) { return is_simm(x, 11); }
283 static bool is_simm12(intptr_t x) { return is_simm(x, 12); }
284 static bool is_simm13(intptr_t x) { return is_simm(x, 13); }
285 static bool is_simm16(intptr_t x) { return is_simm(x, 16); }
286 static bool is_simm26(intptr_t x) { return is_simm(x, 26); }
287 static bool is_simm32(intptr_t x) { return is_simm(x, 32); }
288
289 // Accessors
290 CodeSection* code_section() const { return _code_section; }
291 CodeBuffer* code() const { return code_section()->outer(); }
292 int sect() const { return code_section()->index(); }
293 address pc() const { return code_section()->end(); }
294 int offset() const { return code_section()->size(); }
295 int locator() const { return CodeBuffer::locator(offset(), sect()); }
296
297 OopRecorder* oop_recorder() const { return _oop_recorder; }
298 void set_oop_recorder(OopRecorder* r) { _oop_recorder = r; }
299
300 address inst_mark() const { return code_section()->mark(); }
301 void set_inst_mark() { code_section()->set_mark(); }
302 void clear_inst_mark() { code_section()->clear_mark(); }
303
304 // Constants in code
305 void relocate(RelocationHolder const& rspec, int format = 0) {
306 assert(!pd_check_instruction_mark()
307 || inst_mark() == NULL || inst_mark() == code_section()->end(),
308 "call relocate() between instructions");
309 code_section()->relocate(code_section()->end(), rspec, format);
310 }
311 void relocate( relocInfo::relocType rtype, int format = 0) {
312 code_section()->relocate(code_section()->end(), rtype, format);
313 }
314
315 static int code_fill_byte(); // used to pad out odd-sized code buffers
316
317 // Associate a comment with the current offset. It will be printed
318 // along with the disassembly when printing nmethods. Currently
319 // only supported in the instruction section of the code buffer.
320 void block_comment(const char* comment);
321 // Copy str to a buffer that has the same lifetime as the CodeBuffer
322 const char* code_string(const char* str);
323
324 // Label functions
325 void bind(Label& L); // binds an unbound label L to the current code position
326
327 // Move to a different section in the same code buffer.
328 void set_code_section(CodeSection* cs);
329
330 // Inform assembler when generating stub code and relocation info
331 address start_a_stub(int required_space);
332 void end_a_stub();
333 // Ditto for constants.
334 address start_a_const(int required_space, int required_align = sizeof(double));
335 void end_a_const(CodeSection* cs); // Pass the codesection to continue in (insts or stubs?).
336
337 // constants support
338 //
339 // We must remember the code section (insts or stubs) in c1
340 // so we can reset to the proper section in end_a_const().
341 address long_constant(jlong c) {
342 CodeSection* c1 = _code_section;
343 address ptr = start_a_const(sizeof(c), sizeof(c));
344 if (ptr != NULL) {
345 emit_int64(c);
346 end_a_const(c1);
347 }
348 return ptr;
349 }
350 address double_constant(jdouble c) {
351 CodeSection* c1 = _code_section;
352 address ptr = start_a_const(sizeof(c), sizeof(c));
353 if (ptr != NULL) {
354 emit_double(c);
355 end_a_const(c1);
356 }
357 return ptr;
358 }
359 address float_constant(jfloat c) {
360 CodeSection* c1 = _code_section;
361 address ptr = start_a_const(sizeof(c), sizeof(c));
362 if (ptr != NULL) {
363 emit_float(c);
364 end_a_const(c1);
365 }
366 return ptr;
367 }
368 address address_constant(address c) {
369 CodeSection* c1 = _code_section;
370 address ptr = start_a_const(sizeof(c), sizeof(c));
371 if (ptr != NULL) {
372 emit_address(c);
373 end_a_const(c1);
374 }
375 return ptr;
376 }
377 address address_constant(address c, RelocationHolder const& rspec) {
378 CodeSection* c1 = _code_section;
379 address ptr = start_a_const(sizeof(c), sizeof(c));
380 if (ptr != NULL) {
381 relocate(rspec);
382 emit_address(c);
383 end_a_const(c1);
384 }
385 return ptr;
386 }
387
388 // Bootstrapping aid to cope with delayed determination of constants.
389 // Returns a static address which will eventually contain the constant.
390 // The value zero (NULL) stands instead of a constant which is still uncomputed.
391 // Thus, the eventual value of the constant must not be zero.
392 // This is fine, since this is designed for embedding object field
393 // offsets in code which must be generated before the object class is loaded.
394 // Field offsets are never zero, since an object's header (mark word)
395 // is located at offset zero.
396 RegisterOrConstant delayed_value(int(*value_fn)(), Register tmp, int offset = 0);
397 RegisterOrConstant delayed_value(address(*value_fn)(), Register tmp, int offset = 0);
398 virtual RegisterOrConstant delayed_value_impl(intptr_t* delayed_value_addr, Register tmp, int offset) = 0;
399 // Last overloading is platform-dependent; look in assembler_<arch>.cpp.
400 static intptr_t* delayed_value_addr(int(*constant_fn)());
401 static intptr_t* delayed_value_addr(address(*constant_fn)());
402 static void update_delayed_values();
403
404 // Bang stack to trigger StackOverflowError at a safe location
405 // implementation delegates to machine-specific bang_stack_with_offset
406 void generate_stack_overflow_check( int frame_size_in_bytes );
407 virtual void bang_stack_with_offset(int offset) = 0;
408
409
410 /**
411 * A platform-dependent method to patch a jump instruction that refers
412 * to this label.
413 *
414 * @param branch the location of the instruction to patch
415 * @param masm the assembler which generated the branch
416 */
417 void pd_patch_instruction(address branch, address target);
418
419 };
420
421 #include CPU_HEADER(assembler)
422
423 #endif // SHARE_VM_ASM_ASSEMBLER_HPP