1 /*
2 * Copyright (c) 1997, 2014, 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
37 // This file contains platform-independent assembler declarations.
38
39 class MacroAssembler;
40 class AbstractAssembler;
41 class Label;
42
43 /**
44 * Labels represent destinations for control transfer instructions. Such
45 * instructions can accept a Label as their target argument. A Label is
46 * bound to the current location in the code stream by calling the
47 * MacroAssembler's 'bind' method, which in turn calls the Label's 'bind'
48 * method. A Label may be referenced by an instruction before it's bound
49 * (i.e., 'forward referenced'). 'bind' stores the current code offset
50 * in the Label object.
51 *
52 * If an instruction references a bound Label, the offset field(s) within
53 * the instruction are immediately filled in based on the Label's code
54 * offset. If an instruction references an unbound label, that
55 * instruction is put on a list of instructions that must be patched
56 * (i.e., 'resolved') when the Label is bound.
57 *
58 * 'bind' will call the platform-specific 'patch_instruction' method to
59 * fill in the offset field(s) for each unresolved instruction (if there
60 * are any). 'patch_instruction' lives in one of the
61 * cpu/<arch>/vm/assembler_<arch>* files.
62 *
63 * Instead of using a linked list of unresolved instructions, a Label has
64 * an array of unresolved instruction code offsets. _patch_index
65 * contains the total number of forward references. If the Label's array
66 * overflows (i.e., _patch_index grows larger than the array size), a
67 * GrowableArray is allocated to hold the remaining offsets. (The cache
68 * size is 4 for now, which handles over 99.5% of the cases)
69 *
70 * Labels may only be used within a single CodeSection. If you need
71 * to create references between code sections, use explicit relocations.
72 */
73 class Label VALUE_OBJ_CLASS_SPEC {
74 private:
75 enum { PatchCacheSize = 4 };
76
77 // _loc encodes both the binding state (via its sign)
78 // and the binding locator (via its value) of a label.
79 //
80 // _loc >= 0 bound label, loc() encodes the target (jump) position
81 // _loc == -1 unbound label
82 int _loc;
83
84 // References to instructions that jump to this unresolved label.
85 // These instructions need to be patched when the label is bound
86 // using the platform-specific patchInstruction() method.
87 //
88 // To avoid having to allocate from the C-heap each time, we provide
89 // a local cache and use the overflow only if we exceed the local cache
90 int _patches[PatchCacheSize];
91 int _patch_index;
92 GrowableArray<int>* _patch_overflow;
93
94 Label(const Label&) { ShouldNotReachHere(); }
95
96 public:
97
98 /**
99 * After binding, be sure 'patch_instructions' is called later to link
100 */
101 void bind_loc(int loc) {
102 assert(loc >= 0, "illegal locator");
103 assert(_loc == -1, "already bound");
104 _loc = loc;
105 }
106 void bind_loc(int pos, int sect) { bind_loc(CodeBuffer::locator(pos, sect)); }
107
108 #ifndef PRODUCT
109 // Iterates over all unresolved instructions for printing
110 void print_instructions(MacroAssembler* masm) const;
111 #endif // PRODUCT
112
113 /**
114 * Returns the position of the the Label in the code buffer
115 * The position is a 'locator', which encodes both offset and section.
116 */
117 int loc() const {
118 assert(_loc >= 0, "unbound label");
119 return _loc;
120 }
121 int loc_pos() const { return CodeBuffer::locator_pos(loc()); }
122 int loc_sect() const { return CodeBuffer::locator_sect(loc()); }
123
124 bool is_bound() const { return _loc >= 0; }
125 bool is_unbound() const { return _loc == -1 && _patch_index > 0; }
126 bool is_unused() const { return _loc == -1 && _patch_index == 0; }
127
128 /**
129 * Adds a reference to an unresolved displacement instruction to
130 * this unbound label
131 *
132 * @param cb the code buffer being patched
133 * @param branch_loc the locator of the branch instruction in the code buffer
134 */
135 void add_patch_at(CodeBuffer* cb, int branch_loc);
136
137 /**
138 * Iterate over the list of patches, resolving the instructions
139 * Call patch_instruction on each 'branch_loc' value
140 */
141 void patch_instructions(MacroAssembler* masm);
142
143 void init() {
144 _loc = -1;
145 _patch_index = 0;
146 _patch_overflow = NULL;
147 }
148
149 Label() {
150 init();
151 }
152 };
153
154 // A union type for code which has to assemble both constant and
155 // non-constant operands, when the distinction cannot be made
156 // statically.
157 class RegisterOrConstant VALUE_OBJ_CLASS_SPEC {
158 private:
159 Register _r;
160 intptr_t _c;
161
162 public:
163 RegisterOrConstant(): _r(noreg), _c(0) {}
164 RegisterOrConstant(Register r): _r(r), _c(0) {}
165 RegisterOrConstant(intptr_t c): _r(noreg), _c(c) {}
166
167 Register as_register() const { assert(is_register(),""); return _r; }
168 intptr_t as_constant() const { assert(is_constant(),""); return _c; }
169
170 Register register_or_noreg() const { return _r; }
171 intptr_t constant_or_zero() const { return _c; }
172
173 bool is_register() const { return _r != noreg; }
174 bool is_constant() const { return _r == noreg; }
175 };
176
177 // The Abstract Assembler: Pure assembler doing NO optimizations on the
178 // instruction level; i.e., what you write is what you get.
179 // The Assembler is generating code into a CodeBuffer.
180 class AbstractAssembler : public ResourceObj {
181 friend class Label;
182
183 protected:
184 CodeSection* _code_section; // section within the code buffer
185 OopRecorder* _oop_recorder; // support for relocInfo::oop_type
186
187 public:
188 // Code emission & accessing
189 address addr_at(int pos) const { return code_section()->start() + pos; }
190
191 protected:
192 // This routine is called with a label is used for an address.
193 // Labels and displacements truck in offsets, but target must return a PC.
194 address target(Label& L) { return code_section()->target(L, pc()); }
195
196 bool is8bit(int x) const { return -0x80 <= x && x < 0x80; }
197 bool isByte(int x) const { return 0 <= x && x < 0x100; }
198 bool isShiftCount(int x) const { return 0 <= x && x < 32; }
199
200 // Instruction boundaries (required when emitting relocatable values).
201 class InstructionMark: public StackObj {
202 private:
203 AbstractAssembler* _assm;
204
205 public:
206 InstructionMark(AbstractAssembler* assm) : _assm(assm) {
207 assert(assm->inst_mark() == NULL, "overlapping instructions");
208 _assm->set_inst_mark();
209 }
210 ~InstructionMark() {
211 _assm->clear_inst_mark();
212 }
213 };
214 friend class InstructionMark;
215 #ifdef ASSERT
216 // Make it return true on platforms which need to verify
217 // instruction boundaries for some operations.
218 static bool pd_check_instruction_mark();
219
220 // Add delta to short branch distance to verify that it still fit into imm8.
221 int _short_branch_delta;
222
223 int short_branch_delta() const { return _short_branch_delta; }
224 void set_short_branch_delta() { _short_branch_delta = 32; }
225 void clear_short_branch_delta() { _short_branch_delta = 0; }
226
227 class ShortBranchVerifier: public StackObj {
228 private:
229 AbstractAssembler* _assm;
230
231 public:
232 ShortBranchVerifier(AbstractAssembler* assm) : _assm(assm) {
233 assert(assm->short_branch_delta() == 0, "overlapping instructions");
234 _assm->set_short_branch_delta();
235 }
236 ~ShortBranchVerifier() {
237 _assm->clear_short_branch_delta();
238 }
239 };
240 #else
241 // Dummy in product.
242 class ShortBranchVerifier: public StackObj {
243 public:
244 ShortBranchVerifier(AbstractAssembler* assm) {}
245 };
246 #endif
247
248 public:
249
250 // Creation
251 AbstractAssembler(CodeBuffer* code);
252
253 // ensure buf contains all code (call this before using/copying the code)
254 void flush();
255
256 void emit_int8( int8_t x) { code_section()->emit_int8( x); }
257 void emit_int16( int16_t x) { code_section()->emit_int16( x); }
258 void emit_int32( int32_t x) { code_section()->emit_int32( x); }
259 void emit_int64( int64_t x) { code_section()->emit_int64( x); }
260
261 void emit_float( jfloat x) { code_section()->emit_float( x); }
262 void emit_double( jdouble x) { code_section()->emit_double( x); }
263 void emit_address(address x) { code_section()->emit_address(x); }
264
265 // min and max values for signed immediate ranges
266 static int min_simm(int nbits) { return -(intptr_t(1) << (nbits - 1)) ; }
267 static int max_simm(int nbits) { return (intptr_t(1) << (nbits - 1)) - 1; }
268
269 // Define some:
270 static int min_simm10() { return min_simm(10); }
271 static int min_simm13() { return min_simm(13); }
272 static int min_simm16() { return min_simm(16); }
273
274 // Test if x is within signed immediate range for nbits
275 static bool is_simm(intptr_t x, int nbits) { return min_simm(nbits) <= x && x <= max_simm(nbits); }
276
277 // Define some:
278 static bool is_simm5( intptr_t x) { return is_simm(x, 5 ); }
279 static bool is_simm8( intptr_t x) { return is_simm(x, 8 ); }
280 static bool is_simm10(intptr_t x) { return is_simm(x, 10); }
281 static bool is_simm11(intptr_t x) { return is_simm(x, 11); }
282 static bool is_simm12(intptr_t x) { return is_simm(x, 12); }
283 static bool is_simm13(intptr_t x) { return is_simm(x, 13); }
284 static bool is_simm16(intptr_t x) { return is_simm(x, 16); }
285 static bool is_simm26(intptr_t x) { return is_simm(x, 26); }
286 static bool is_simm32(intptr_t x) { return is_simm(x, 32); }
287
288 // Accessors
289 CodeSection* code_section() const { return _code_section; }
290 CodeBuffer* code() const { return code_section()->outer(); }
291 int sect() const { return code_section()->index(); }
292 address pc() const { return code_section()->end(); }
293 int offset() const { return code_section()->size(); }
294 int locator() const { return CodeBuffer::locator(offset(), sect()); }
295
296 OopRecorder* oop_recorder() const { return _oop_recorder; }
297 void set_oop_recorder(OopRecorder* r) { _oop_recorder = r; }
298
299 address inst_mark() const { return code_section()->mark(); }
300 void set_inst_mark() { code_section()->set_mark(); }
301 void clear_inst_mark() { code_section()->clear_mark(); }
302
303 // Constants in code
304 void relocate(RelocationHolder const& rspec, int format = 0) {
305 assert(!pd_check_instruction_mark()
306 || inst_mark() == NULL || inst_mark() == code_section()->end(),
307 "call relocate() between instructions");
308 code_section()->relocate(code_section()->end(), rspec, format);
309 }
310 void relocate( relocInfo::relocType rtype, int format = 0) {
311 code_section()->relocate(code_section()->end(), rtype, format);
312 }
313
314 static int code_fill_byte(); // used to pad out odd-sized code buffers
315
316 // Associate a comment with the current offset. It will be printed
317 // along with the disassembly when printing nmethods. Currently
318 // only supported in the instruction section of the code buffer.
319 void block_comment(const char* comment);
320 // Copy str to a buffer that has the same lifetime as the CodeBuffer
321 const char* code_string(const char* str);
322
323 // Label functions
324 void bind(Label& L); // binds an unbound label L to the current code position
325
326 // Move to a different section in the same code buffer.
327 void set_code_section(CodeSection* cs);
328
329 // Inform assembler when generating stub code and relocation info
330 address start_a_stub(int required_space);
331 void end_a_stub();
332 // Ditto for constants.
333 address start_a_const(int required_space, int required_align = sizeof(double));
334 void end_a_const(CodeSection* cs); // Pass the codesection to continue in (insts or stubs?).
335
336 // constants support
337 //
338 // We must remember the code section (insts or stubs) in c1
339 // so we can reset to the proper section in end_a_const().
340 address int_constant(jint c) {
341 CodeSection* c1 = _code_section;
342 address ptr = start_a_const(sizeof(c), sizeof(c));
343 if (ptr != NULL) {
344 emit_int32(c);
345 end_a_const(c1);
346 }
347 return ptr;
348 }
349 address long_constant(jlong c) {
350 CodeSection* c1 = _code_section;
351 address ptr = start_a_const(sizeof(c), sizeof(c));
352 if (ptr != NULL) {
353 emit_int64(c);
354 end_a_const(c1);
355 }
356 return ptr;
357 }
358 address double_constant(jdouble c) {
359 CodeSection* c1 = _code_section;
360 address ptr = start_a_const(sizeof(c), sizeof(c));
361 if (ptr != NULL) {
362 emit_double(c);
363 end_a_const(c1);
364 }
365 return ptr;
366 }
367 address float_constant(jfloat c) {
368 CodeSection* c1 = _code_section;
369 address ptr = start_a_const(sizeof(c), sizeof(c));
370 if (ptr != NULL) {
371 emit_float(c);
372 end_a_const(c1);
373 }
374 return ptr;
375 }
376 address address_constant(address c) {
377 CodeSection* c1 = _code_section;
378 address ptr = start_a_const(sizeof(c), sizeof(c));
379 if (ptr != NULL) {
380 emit_address(c);
381 end_a_const(c1);
382 }
383 return ptr;
384 }
385 address address_constant(address c, RelocationHolder const& rspec) {
386 CodeSection* c1 = _code_section;
387 address ptr = start_a_const(sizeof(c), sizeof(c));
388 if (ptr != NULL) {
389 relocate(rspec);
390 emit_address(c);
391 end_a_const(c1);
392 }
393 return ptr;
394 }
395
396 // Bootstrapping aid to cope with delayed determination of constants.
397 // Returns a static address which will eventually contain the constant.
398 // The value zero (NULL) stands instead of a constant which is still uncomputed.
399 // Thus, the eventual value of the constant must not be zero.
400 // This is fine, since this is designed for embedding object field
401 // offsets in code which must be generated before the object class is loaded.
402 // Field offsets are never zero, since an object's header (mark word)
403 // is located at offset zero.
404 RegisterOrConstant delayed_value(int(*value_fn)(), Register tmp, int offset = 0);
405 RegisterOrConstant delayed_value(address(*value_fn)(), Register tmp, int offset = 0);
406 virtual RegisterOrConstant delayed_value_impl(intptr_t* delayed_value_addr, Register tmp, int offset) = 0;
407 // Last overloading is platform-dependent; look in assembler_<arch>.cpp.
408 static intptr_t* delayed_value_addr(int(*constant_fn)());
409 static intptr_t* delayed_value_addr(address(*constant_fn)());
410 static void update_delayed_values();
411
412 // Bang stack to trigger StackOverflowError at a safe location
413 // implementation delegates to machine-specific bang_stack_with_offset
414 void generate_stack_overflow_check( int frame_size_in_bytes );
415 virtual void bang_stack_with_offset(int offset) = 0;
416
417
418 /**
419 * A platform-dependent method to patch a jump instruction that refers
420 * to this label.
421 *
422 * @param branch the location of the instruction to patch
423 * @param masm the assembler which generated the branch
424 */
425 void pd_patch_instruction(address branch, address target);
426
427 };
428
429 #ifdef TARGET_ARCH_x86
430 # include "assembler_x86.hpp"
431 #endif
432 #ifdef TARGET_ARCH_sparc
433 # include "assembler_sparc.hpp"
434 #endif
435 #ifdef TARGET_ARCH_zero
436 # include "assembler_zero.hpp"
437 #endif
438 #ifdef TARGET_ARCH_arm
439 # include "assembler_arm.hpp"
440 #endif
441 #ifdef TARGET_ARCH_ppc
442 # include "assembler_ppc.hpp"
443 #endif
444 #ifdef TARGET_ARCH_aarch64
445 # include "assembler_aarch64.hpp"
446 #endif
447
448
449 #endif // SHARE_VM_ASM_ASSEMBLER_HPP