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