1 /*
2 * Copyright (c) 1997, 2018, 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 "code/oopRecorder.hpp"
30 #include "code/relocInfo.hpp"
31 #include "memory/allocation.hpp"
32 #include "utilities/debug.hpp"
33 #include "utilities/growableArray.hpp"
34 #include "utilities/top.hpp"
35
36 #ifdef TARGET_ARCH_x86
37 # include "register_x86.hpp"
38 # include "vm_version_x86.hpp"
39 #endif
40 #ifdef TARGET_ARCH_sparc
41 # include "register_sparc.hpp"
42 # include "vm_version_sparc.hpp"
43 #endif
44 #ifdef TARGET_ARCH_zero
45 # include "register_zero.hpp"
46 # include "vm_version_zero.hpp"
47 #endif
48 #ifdef TARGET_ARCH_arm
49 # include "register_arm.hpp"
50 # include "vm_version_arm.hpp"
51 #endif
52 #ifdef TARGET_ARCH_ppc
53 # include "register_ppc.hpp"
54 # include "vm_version_ppc.hpp"
55 #endif
56
57 // This file contains platform-independent assembler declarations.
58
59 class MacroAssembler;
60 class AbstractAssembler;
61 class Label;
62
63 /**
64 * Labels represent destinations for control transfer instructions. Such
65 * instructions can accept a Label as their target argument. A Label is
66 * bound to the current location in the code stream by calling the
67 * MacroAssembler's 'bind' method, which in turn calls the Label's 'bind'
68 * method. A Label may be referenced by an instruction before it's bound
69 * (i.e., 'forward referenced'). 'bind' stores the current code offset
70 * in the Label object.
71 *
72 * If an instruction references a bound Label, the offset field(s) within
73 * the instruction are immediately filled in based on the Label's code
74 * offset. If an instruction references an unbound label, that
75 * instruction is put on a list of instructions that must be patched
76 * (i.e., 'resolved') when the Label is bound.
77 *
78 * 'bind' will call the platform-specific 'patch_instruction' method to
79 * fill in the offset field(s) for each unresolved instruction (if there
80 * are any). 'patch_instruction' lives in one of the
81 * cpu/<arch>/vm/assembler_<arch>* files.
82 *
83 * Instead of using a linked list of unresolved instructions, a Label has
84 * an array of unresolved instruction code offsets. _patch_index
85 * contains the total number of forward references. If the Label's array
86 * overflows (i.e., _patch_index grows larger than the array size), a
87 * GrowableArray is allocated to hold the remaining offsets. (The cache
88 * size is 4 for now, which handles over 99.5% of the cases)
89 *
90 * Labels may only be used within a single CodeSection. If you need
91 * to create references between code sections, use explicit relocations.
92 */
93 class Label VALUE_OBJ_CLASS_SPEC {
94 private:
95 enum { PatchCacheSize = 4 };
96
97 // _loc encodes both the binding state (via its sign)
98 // and the binding locator (via its value) of a label.
99 //
100 // _loc >= 0 bound label, loc() encodes the target (jump) position
101 // _loc == -1 unbound label
102 int _loc;
103
104 // References to instructions that jump to this unresolved label.
105 // These instructions need to be patched when the label is bound
106 // using the platform-specific patchInstruction() method.
107 //
108 // To avoid having to allocate from the C-heap each time, we provide
109 // a local cache and use the overflow only if we exceed the local cache
110 int _patches[PatchCacheSize];
111 int _patch_index;
112 GrowableArray<int>* _patch_overflow;
113
114 Label(const Label&) { ShouldNotReachHere(); }
115
116 public:
117
118 /**
119 * After binding, be sure 'patch_instructions' is called later to link
120 */
121 void bind_loc(int loc) {
122 assert(loc >= 0, "illegal locator");
123 assert(_loc == -1, "already bound");
124 _loc = loc;
125 }
126 void bind_loc(int pos, int sect) { bind_loc(CodeBuffer::locator(pos, sect)); }
127
128 #ifndef PRODUCT
129 // Iterates over all unresolved instructions for printing
130 void print_instructions(MacroAssembler* masm) const;
131 #endif // PRODUCT
132
133 /**
134 * Returns the position of the the Label in the code buffer
135 * The position is a 'locator', which encodes both offset and section.
136 */
137 int loc() const {
138 assert(_loc >= 0, "unbound label");
139 return _loc;
140 }
141 int loc_pos() const { return CodeBuffer::locator_pos(loc()); }
142 int loc_sect() const { return CodeBuffer::locator_sect(loc()); }
143
144 bool is_bound() const { return _loc >= 0; }
145 bool is_unbound() const { return _loc == -1 && _patch_index > 0; }
146 bool is_unused() const { return _loc == -1 && _patch_index == 0; }
147
148 /**
149 * Adds a reference to an unresolved displacement instruction to
150 * this unbound label
151 *
152 * @param cb the code buffer being patched
153 * @param branch_loc the locator of the branch instruction in the code buffer
154 */
155 void add_patch_at(CodeBuffer* cb, int branch_loc);
156
157 /**
158 * Iterate over the list of patches, resolving the instructions
159 * Call patch_instruction on each 'branch_loc' value
160 */
161 void patch_instructions(MacroAssembler* masm);
162
163 void init() {
164 _loc = -1;
165 _patch_index = 0;
166 _patch_overflow = NULL;
167 }
168
169 Label() {
170 init();
171 }
172
173 ~Label() {
174 assert(is_bound() || is_unused(), "Label was never bound to a location, but it was used as a jmp target");
175 }
176
177 void reset() {
178 init(); //leave _patch_overflow because it points to CodeBuffer.
179 }
180 };
181
182 // A union type for code which has to assemble both constant and
183 // non-constant operands, when the distinction cannot be made
184 // statically.
185 class RegisterOrConstant VALUE_OBJ_CLASS_SPEC {
186 private:
187 Register _r;
188 intptr_t _c;
189
190 public:
191 RegisterOrConstant(): _r(noreg), _c(0) {}
192 RegisterOrConstant(Register r): _r(r), _c(0) {}
193 RegisterOrConstant(intptr_t c): _r(noreg), _c(c) {}
194
195 Register as_register() const { assert(is_register(),""); return _r; }
196 intptr_t as_constant() const { assert(is_constant(),""); return _c; }
197
198 Register register_or_noreg() const { return _r; }
199 intptr_t constant_or_zero() const { return _c; }
200
201 bool is_register() const { return _r != noreg; }
202 bool is_constant() const { return _r == noreg; }
203 };
204
205 // The Abstract Assembler: Pure assembler doing NO optimizations on the
206 // instruction level; i.e., what you write is what you get.
207 // The Assembler is generating code into a CodeBuffer.
208 class AbstractAssembler : public ResourceObj {
209 friend class Label;
210
211 protected:
212 CodeSection* _code_section; // section within the code buffer
213 OopRecorder* _oop_recorder; // support for relocInfo::oop_type
214
215 public:
216 // Code emission & accessing
217 address addr_at(int pos) const { return code_section()->start() + pos; }
218
219 protected:
220 // This routine is called with a label is used for an address.
221 // Labels and displacements truck in offsets, but target must return a PC.
222 address target(Label& L) { return code_section()->target(L, pc()); }
223
224 bool is8bit(int x) const { return -0x80 <= x && x < 0x80; }
225 bool isByte(int x) const { return 0 <= x && x < 0x100; }
226 bool isShiftCount(int x) const { return 0 <= x && x < 32; }
227
228 // Instruction boundaries (required when emitting relocatable values).
229 class InstructionMark: public StackObj {
230 private:
231 AbstractAssembler* _assm;
232
233 public:
234 InstructionMark(AbstractAssembler* assm) : _assm(assm) {
235 assert(assm->inst_mark() == NULL, "overlapping instructions");
236 _assm->set_inst_mark();
237 }
238 ~InstructionMark() {
239 _assm->clear_inst_mark();
240 }
241 };
242 friend class InstructionMark;
243 #ifdef ASSERT
244 // Make it return true on platforms which need to verify
245 // instruction boundaries for some operations.
246 static bool pd_check_instruction_mark();
247
248 // Add delta to short branch distance to verify that it still fit into imm8.
249 int _short_branch_delta;
250
251 int short_branch_delta() const { return _short_branch_delta; }
252 void set_short_branch_delta() { _short_branch_delta = 32; }
253 void clear_short_branch_delta() { _short_branch_delta = 0; }
254
255 class ShortBranchVerifier: public StackObj {
256 private:
257 AbstractAssembler* _assm;
258
259 public:
260 ShortBranchVerifier(AbstractAssembler* assm) : _assm(assm) {
261 assert(assm->short_branch_delta() == 0, "overlapping instructions");
262 _assm->set_short_branch_delta();
263 }
264 ~ShortBranchVerifier() {
265 _assm->clear_short_branch_delta();
266 }
267 };
268 #else
269 // Dummy in product.
270 class ShortBranchVerifier: public StackObj {
271 public:
272 ShortBranchVerifier(AbstractAssembler* assm) {}
273 };
274 #endif
275
276 public:
277
278 // Creation
279 AbstractAssembler(CodeBuffer* code);
280
281 // ensure buf contains all code (call this before using/copying the code)
282 void flush();
283
284 void emit_int8( int8_t x) { code_section()->emit_int8( x); }
285 void emit_int16( int16_t x) { code_section()->emit_int16( x); }
286 void emit_int32( int32_t x) { code_section()->emit_int32( x); }
287 void emit_int64( int64_t x) { code_section()->emit_int64( x); }
288
289 void emit_float( jfloat x) { code_section()->emit_float( x); }
290 void emit_double( jdouble x) { code_section()->emit_double( x); }
291 void emit_address(address x) { code_section()->emit_address(x); }
292
293 // min and max values for signed immediate ranges
294 static int min_simm(int nbits) { return -(intptr_t(1) << (nbits - 1)) ; }
295 static int max_simm(int nbits) { return (intptr_t(1) << (nbits - 1)) - 1; }
296
297 // Define some:
298 static int min_simm10() { return min_simm(10); }
299 static int min_simm13() { return min_simm(13); }
300 static int min_simm16() { return min_simm(16); }
301
302 // Test if x is within signed immediate range for nbits
303 static bool is_simm(intptr_t x, int nbits) { return min_simm(nbits) <= x && x <= max_simm(nbits); }
304
305 // Define some:
306 static bool is_simm5( intptr_t x) { return is_simm(x, 5 ); }
307 static bool is_simm8( intptr_t x) { return is_simm(x, 8 ); }
308 static bool is_simm10(intptr_t x) { return is_simm(x, 10); }
309 static bool is_simm11(intptr_t x) { return is_simm(x, 11); }
310 static bool is_simm12(intptr_t x) { return is_simm(x, 12); }
311 static bool is_simm13(intptr_t x) { return is_simm(x, 13); }
312 static bool is_simm16(intptr_t x) { return is_simm(x, 16); }
313 static bool is_simm26(intptr_t x) { return is_simm(x, 26); }
314 static bool is_simm32(intptr_t x) { return is_simm(x, 32); }
315
316 // Accessors
317 CodeSection* code_section() const { return _code_section; }
318 CodeBuffer* code() const { return code_section()->outer(); }
319 int sect() const { return code_section()->index(); }
320 address pc() const { return code_section()->end(); }
321 int offset() const { return code_section()->size(); }
322 int locator() const { return CodeBuffer::locator(offset(), sect()); }
323
324 OopRecorder* oop_recorder() const { return _oop_recorder; }
325 void set_oop_recorder(OopRecorder* r) { _oop_recorder = r; }
326
327 address inst_mark() const { return code_section()->mark(); }
328 void set_inst_mark() { code_section()->set_mark(); }
329 void clear_inst_mark() { code_section()->clear_mark(); }
330
331 // Constants in code
332 void relocate(RelocationHolder const& rspec, int format = 0) {
333 assert(!pd_check_instruction_mark()
334 || inst_mark() == NULL || inst_mark() == code_section()->end(),
335 "call relocate() between instructions");
336 code_section()->relocate(code_section()->end(), rspec, format);
337 }
338 void relocate( relocInfo::relocType rtype, int format = 0) {
339 code_section()->relocate(code_section()->end(), rtype, format);
340 }
341
342 static int code_fill_byte(); // used to pad out odd-sized code buffers
343
344 // Associate a comment with the current offset. It will be printed
345 // along with the disassembly when printing nmethods. Currently
346 // only supported in the instruction section of the code buffer.
347 void block_comment(const char* comment);
348 // Copy str to a buffer that has the same lifetime as the CodeBuffer
349 const char* code_string(const char* str);
350
351 // Label functions
352 void bind(Label& L); // binds an unbound label L to the current code position
353
354 // Move to a different section in the same code buffer.
355 void set_code_section(CodeSection* cs);
356
357 // Inform assembler when generating stub code and relocation info
358 address start_a_stub(int required_space);
359 void end_a_stub();
360 // Ditto for constants.
361 address start_a_const(int required_space, int required_align = sizeof(double));
362 void end_a_const(CodeSection* cs); // Pass the codesection to continue in (insts or stubs?).
363
364 // constants support
365 //
366 // We must remember the code section (insts or stubs) in c1
367 // so we can reset to the proper section in end_a_const().
368 address long_constant(jlong c) {
369 CodeSection* c1 = _code_section;
370 address ptr = start_a_const(sizeof(c), sizeof(c));
371 if (ptr != NULL) {
372 emit_int64(c);
373 end_a_const(c1);
374 }
375 return ptr;
376 }
377 address double_constant(jdouble c) {
378 CodeSection* c1 = _code_section;
379 address ptr = start_a_const(sizeof(c), sizeof(c));
380 if (ptr != NULL) {
381 emit_double(c);
382 end_a_const(c1);
383 }
384 return ptr;
385 }
386 address float_constant(jfloat c) {
387 CodeSection* c1 = _code_section;
388 address ptr = start_a_const(sizeof(c), sizeof(c));
389 if (ptr != NULL) {
390 emit_float(c);
391 end_a_const(c1);
392 }
393 return ptr;
394 }
395 address address_constant(address c) {
396 CodeSection* c1 = _code_section;
397 address ptr = start_a_const(sizeof(c), sizeof(c));
398 if (ptr != NULL) {
399 emit_address(c);
400 end_a_const(c1);
401 }
402 return ptr;
403 }
404 address address_constant(address c, RelocationHolder const& rspec) {
405 CodeSection* c1 = _code_section;
406 address ptr = start_a_const(sizeof(c), sizeof(c));
407 if (ptr != NULL) {
408 relocate(rspec);
409 emit_address(c);
410 end_a_const(c1);
411 }
412 return ptr;
413 }
414
415 // Bootstrapping aid to cope with delayed determination of constants.
416 // Returns a static address which will eventually contain the constant.
417 // The value zero (NULL) stands instead of a constant which is still uncomputed.
418 // Thus, the eventual value of the constant must not be zero.
419 // This is fine, since this is designed for embedding object field
420 // offsets in code which must be generated before the object class is loaded.
421 // Field offsets are never zero, since an object's header (mark word)
422 // is located at offset zero.
423 RegisterOrConstant delayed_value(int(*value_fn)(), Register tmp, int offset = 0);
424 RegisterOrConstant delayed_value(address(*value_fn)(), Register tmp, int offset = 0);
425 virtual RegisterOrConstant delayed_value_impl(intptr_t* delayed_value_addr, Register tmp, int offset) = 0;
426 // Last overloading is platform-dependent; look in assembler_<arch>.cpp.
427 static intptr_t* delayed_value_addr(int(*constant_fn)());
428 static intptr_t* delayed_value_addr(address(*constant_fn)());
429 static void update_delayed_values();
430
431 // Bang stack to trigger StackOverflowError at a safe location
432 // implementation delegates to machine-specific bang_stack_with_offset
433 void generate_stack_overflow_check( int frame_size_in_bytes );
434 virtual void bang_stack_with_offset(int offset) = 0;
435
436
437 /**
438 * A platform-dependent method to patch a jump instruction that refers
439 * to this label.
440 *
441 * @param branch the location of the instruction to patch
442 * @param masm the assembler which generated the branch
443 */
444 void pd_patch_instruction(address branch, address target);
445
446 };
447
448 #ifdef TARGET_ARCH_x86
449 # include "assembler_x86.hpp"
450 #endif
451 #ifdef TARGET_ARCH_sparc
452 # include "assembler_sparc.hpp"
453 #endif
454 #ifdef TARGET_ARCH_zero
455 # include "assembler_zero.hpp"
456 #endif
457 #ifdef TARGET_ARCH_arm
458 # include "assembler_arm.hpp"
459 #endif
460 #ifdef TARGET_ARCH_ppc
461 # include "assembler_ppc.hpp"
462 #endif
463
464
465 #endif // SHARE_VM_ASM_ASSEMBLER_HPP