rev 50906 : JDK-8206075: Cdd an assertion stmt for Assembler's Label

Check all labels and catch unbound labels. Fix a problem for x86.

   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 "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 {
  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  protected:
  97 
  98   // The label will be bound to a location near its users.
  99   bool _is_near;
 100 
 101  public:
 102 
 103   /**
 104    * After binding, be sure 'patch_instructions' is called later to link
 105    */
 106   void bind_loc(int loc) {
 107     assert(loc >= 0, "illegal locator");
 108     assert(_loc == -1, "already bound");
 109     _loc = loc;
 110   }
 111   void bind_loc(int pos, int sect) { bind_loc(CodeBuffer::locator(pos, sect)); }
 112 
 113 #ifndef PRODUCT
 114   // Iterates over all unresolved instructions for printing
 115   void print_instructions(MacroAssembler* masm) const;
 116 #endif // PRODUCT
 117 
 118   /**
 119    * Returns the position of the the Label in the code buffer
 120    * The position is a 'locator', which encodes both offset and section.
 121    */
 122   int loc() const {
 123     assert(_loc >= 0, "unbound label");
 124     return _loc;
 125   }
 126   int loc_pos()  const { return CodeBuffer::locator_pos(loc()); }
 127   int loc_sect() const { return CodeBuffer::locator_sect(loc()); }
 128 
 129   bool is_bound() const    { return _loc >=  0; }
 130   bool is_unbound() const  { return _loc == -1 && _patch_index > 0; }
 131   bool is_unused() const   { return _loc == -1 && _patch_index == 0; }
 132 
 133   // The label will be bound to a location near its users. Users can
 134   // optimize on this information, e.g. generate short branches.
 135   bool is_near()           { return _is_near; }
 136 
 137   /**
 138    * Adds a reference to an unresolved displacement instruction to
 139    * this unbound label
 140    *
 141    * @param cb         the code buffer being patched
 142    * @param branch_loc the locator of the branch instruction in the code buffer
 143    */
 144   void add_patch_at(CodeBuffer* cb, int branch_loc);
 145 
 146   /**
 147    * Iterate over the list of patches, resolving the instructions
 148    * Call patch_instruction on each 'branch_loc' value
 149    */
 150   void patch_instructions(MacroAssembler* masm);
 151 
 152   void init() {
 153     _loc = -1;
 154     _patch_index = 0;
 155     _patch_overflow = NULL;
 156     _is_near = false;
 157   }
 158 
 159   Label() {
 160     init();
 161   }
 162 
 163   ~Label() {
 164     assert(is_bound() || is_unused(), "Label was never bound to a location, but it was used as a jmp target");
 165   }
 166 };
 167 
 168 // A NearLabel must be bound to a location near its users. Users can
 169 // optimize on this information, e.g. generate short branches.
 170 class NearLabel : public Label {
 171  public:
 172   NearLabel() : Label() { _is_near = true; }
 173 };
 174 
 175 // A union type for code which has to assemble both constant and
 176 // non-constant operands, when the distinction cannot be made
 177 // statically.
 178 class RegisterOrConstant {
 179  private:
 180   Register _r;
 181   intptr_t _c;
 182 
 183  public:
 184   RegisterOrConstant(): _r(noreg), _c(0) {}
 185   RegisterOrConstant(Register r): _r(r), _c(0) {}
 186   RegisterOrConstant(intptr_t c): _r(noreg), _c(c) {}
 187 
 188   Register as_register() const { assert(is_register(),""); return _r; }
 189   intptr_t as_constant() const { assert(is_constant(),""); return _c; }
 190 
 191   Register register_or_noreg() const { return _r; }
 192   intptr_t constant_or_zero() const  { return _c; }
 193 
 194   bool is_register() const { return _r != noreg; }
 195   bool is_constant() const { return _r == noreg; }
 196 };
 197 
 198 // The Abstract Assembler: Pure assembler doing NO optimizations on the
 199 // instruction level; i.e., what you write is what you get.
 200 // The Assembler is generating code into a CodeBuffer.
 201 class AbstractAssembler : public ResourceObj  {
 202   friend class Label;
 203 
 204  protected:
 205   CodeSection* _code_section;          // section within the code buffer
 206   OopRecorder* _oop_recorder;          // support for relocInfo::oop_type
 207 
 208  public:
 209   // Code emission & accessing
 210   address addr_at(int pos) const { return code_section()->start() + pos; }
 211 
 212  protected:
 213   // This routine is called with a label is used for an address.
 214   // Labels and displacements truck in offsets, but target must return a PC.
 215   address target(Label& L)             { return code_section()->target(L, pc()); }
 216 
 217   bool is8bit(int x) const             { return -0x80 <= x && x < 0x80; }
 218   bool isByte(int x) const             { return 0 <= x && x < 0x100; }
 219   bool isShiftCount(int x) const       { return 0 <= x && x < 32; }
 220 
 221   // Instruction boundaries (required when emitting relocatable values).
 222   class InstructionMark: public StackObj {
 223    private:
 224     AbstractAssembler* _assm;
 225 
 226    public:
 227     InstructionMark(AbstractAssembler* assm) : _assm(assm) {
 228       assert(assm->inst_mark() == NULL, "overlapping instructions");
 229       _assm->set_inst_mark();
 230     }
 231     ~InstructionMark() {
 232       _assm->clear_inst_mark();
 233     }
 234   };
 235   friend class InstructionMark;
 236 #ifdef ASSERT
 237   // Make it return true on platforms which need to verify
 238   // instruction boundaries for some operations.
 239   static bool pd_check_instruction_mark();
 240 
 241   // Add delta to short branch distance to verify that it still fit into imm8.
 242   int _short_branch_delta;
 243 
 244   int  short_branch_delta() const { return _short_branch_delta; }
 245   void set_short_branch_delta()   { _short_branch_delta = 32; }
 246   void clear_short_branch_delta() { _short_branch_delta = 0; }
 247 
 248   class ShortBranchVerifier: public StackObj {
 249    private:
 250     AbstractAssembler* _assm;
 251 
 252    public:
 253     ShortBranchVerifier(AbstractAssembler* assm) : _assm(assm) {
 254       assert(assm->short_branch_delta() == 0, "overlapping instructions");
 255       _assm->set_short_branch_delta();
 256     }
 257     ~ShortBranchVerifier() {
 258       _assm->clear_short_branch_delta();
 259     }
 260   };
 261 #else
 262   // Dummy in product.
 263   class ShortBranchVerifier: public StackObj {
 264    public:
 265     ShortBranchVerifier(AbstractAssembler* assm) {}
 266   };
 267 #endif
 268 
 269  public:
 270 
 271   // Creation
 272   AbstractAssembler(CodeBuffer* code);
 273 
 274   // ensure buf contains all code (call this before using/copying the code)
 275   void flush();
 276 
 277   void emit_int8(   int8_t  x) { code_section()->emit_int8(   x); }
 278   void emit_int16(  int16_t x) { code_section()->emit_int16(  x); }
 279   void emit_int32(  int32_t x) { code_section()->emit_int32(  x); }
 280   void emit_int64(  int64_t x) { code_section()->emit_int64(  x); }
 281 
 282   void emit_float(  jfloat  x) { code_section()->emit_float(  x); }
 283   void emit_double( jdouble x) { code_section()->emit_double( x); }
 284   void emit_address(address x) { code_section()->emit_address(x); }
 285 
 286   // min and max values for signed immediate ranges
 287   static int min_simm(int nbits) { return -(intptr_t(1) << (nbits - 1))    ; }
 288   static int max_simm(int nbits) { return  (intptr_t(1) << (nbits - 1)) - 1; }
 289 
 290   // Define some:
 291   static int min_simm10() { return min_simm(10); }
 292   static int min_simm13() { return min_simm(13); }
 293   static int min_simm16() { return min_simm(16); }
 294 
 295   // Test if x is within signed immediate range for nbits
 296   static bool is_simm(intptr_t x, int nbits) { return min_simm(nbits) <= x && x <= max_simm(nbits); }
 297 
 298   // Define some:
 299   static bool is_simm5( intptr_t x) { return is_simm(x, 5 ); }
 300   static bool is_simm8( intptr_t x) { return is_simm(x, 8 ); }
 301   static bool is_simm10(intptr_t x) { return is_simm(x, 10); }
 302   static bool is_simm11(intptr_t x) { return is_simm(x, 11); }
 303   static bool is_simm12(intptr_t x) { return is_simm(x, 12); }
 304   static bool is_simm13(intptr_t x) { return is_simm(x, 13); }
 305   static bool is_simm16(intptr_t x) { return is_simm(x, 16); }
 306   static bool is_simm26(intptr_t x) { return is_simm(x, 26); }
 307   static bool is_simm32(intptr_t x) { return is_simm(x, 32); }
 308 
 309   // Accessors
 310   CodeSection*  code_section() const   { return _code_section; }
 311   CodeBuffer*   code()         const   { return code_section()->outer(); }
 312   int           sect()         const   { return code_section()->index(); }
 313   address       pc()           const   { return code_section()->end();   }
 314   int           offset()       const   { return code_section()->size();  }
 315   int           locator()      const   { return CodeBuffer::locator(offset(), sect()); }
 316 
 317   OopRecorder*  oop_recorder() const   { return _oop_recorder; }
 318   void      set_oop_recorder(OopRecorder* r) { _oop_recorder = r; }
 319 
 320   address       inst_mark() const { return code_section()->mark();       }
 321   void      set_inst_mark()       {        code_section()->set_mark();   }
 322   void    clear_inst_mark()       {        code_section()->clear_mark(); }
 323 
 324   // Constants in code
 325   void relocate(RelocationHolder const& rspec, int format = 0) {
 326     assert(!pd_check_instruction_mark()
 327         || inst_mark() == NULL || inst_mark() == code_section()->end(),
 328         "call relocate() between instructions");
 329     code_section()->relocate(code_section()->end(), rspec, format);
 330   }
 331   void relocate(   relocInfo::relocType rtype, int format = 0) {
 332     code_section()->relocate(code_section()->end(), rtype, format);
 333   }
 334 
 335   static int code_fill_byte();         // used to pad out odd-sized code buffers
 336 
 337   // Associate a comment with the current offset.  It will be printed
 338   // along with the disassembly when printing nmethods.  Currently
 339   // only supported in the instruction section of the code buffer.
 340   void block_comment(const char* comment);
 341   // Copy str to a buffer that has the same lifetime as the CodeBuffer
 342   const char* code_string(const char* str);
 343 
 344   // Label functions
 345   void bind(Label& L); // binds an unbound label L to the current code position
 346 
 347   // Move to a different section in the same code buffer.
 348   void set_code_section(CodeSection* cs);
 349 
 350   // Inform assembler when generating stub code and relocation info
 351   address    start_a_stub(int required_space);
 352   void       end_a_stub();
 353   // Ditto for constants.
 354   address    start_a_const(int required_space, int required_align = sizeof(double));
 355   void       end_a_const(CodeSection* cs);  // Pass the codesection to continue in (insts or stubs?).
 356 
 357   // constants support
 358   //
 359   // We must remember the code section (insts or stubs) in c1
 360   // so we can reset to the proper section in end_a_const().
 361   address int_constant(jint c) {
 362     CodeSection* c1 = _code_section;
 363     address ptr = start_a_const(sizeof(c), sizeof(c));
 364     if (ptr != NULL) {
 365       emit_int32(c);
 366       end_a_const(c1);
 367     }
 368     return ptr;
 369   }
 370   address long_constant(jlong c) {
 371     CodeSection* c1 = _code_section;
 372     address ptr = start_a_const(sizeof(c), sizeof(c));
 373     if (ptr != NULL) {
 374       emit_int64(c);
 375       end_a_const(c1);
 376     }
 377     return ptr;
 378   }
 379   address double_constant(jdouble c) {
 380     CodeSection* c1 = _code_section;
 381     address ptr = start_a_const(sizeof(c), sizeof(c));
 382     if (ptr != NULL) {
 383       emit_double(c);
 384       end_a_const(c1);
 385     }
 386     return ptr;
 387   }
 388   address float_constant(jfloat c) {
 389     CodeSection* c1 = _code_section;
 390     address ptr = start_a_const(sizeof(c), sizeof(c));
 391     if (ptr != NULL) {
 392       emit_float(c);
 393       end_a_const(c1);
 394     }
 395     return ptr;
 396   }
 397   address address_constant(address c) {
 398     CodeSection* c1 = _code_section;
 399     address ptr = start_a_const(sizeof(c), sizeof(c));
 400     if (ptr != NULL) {
 401       emit_address(c);
 402       end_a_const(c1);
 403     }
 404     return ptr;
 405   }
 406   address address_constant(address c, RelocationHolder const& rspec) {
 407     CodeSection* c1 = _code_section;
 408     address ptr = start_a_const(sizeof(c), sizeof(c));
 409     if (ptr != NULL) {
 410       relocate(rspec);
 411       emit_address(c);
 412       end_a_const(c1);
 413     }
 414     return ptr;
 415   }
 416 
 417   // Bootstrapping aid to cope with delayed determination of constants.
 418   // Returns a static address which will eventually contain the constant.
 419   // The value zero (NULL) stands instead of a constant which is still uncomputed.
 420   // Thus, the eventual value of the constant must not be zero.
 421   // This is fine, since this is designed for embedding object field
 422   // offsets in code which must be generated before the object class is loaded.
 423   // Field offsets are never zero, since an object's header (mark word)
 424   // is located at offset zero.
 425   RegisterOrConstant delayed_value(int(*value_fn)(), Register tmp, int offset = 0);
 426   RegisterOrConstant delayed_value(address(*value_fn)(), Register tmp, int offset = 0);
 427   virtual RegisterOrConstant delayed_value_impl(intptr_t* delayed_value_addr, Register tmp, int offset) = 0;
 428   // Last overloading is platform-dependent; look in assembler_<arch>.cpp.
 429   static intptr_t* delayed_value_addr(int(*constant_fn)());
 430   static intptr_t* delayed_value_addr(address(*constant_fn)());
 431   static void update_delayed_values();
 432 
 433   // Bang stack to trigger StackOverflowError at a safe location
 434   // implementation delegates to machine-specific bang_stack_with_offset
 435   void generate_stack_overflow_check( int frame_size_in_bytes );
 436   virtual void bang_stack_with_offset(int offset) = 0;
 437 
 438 
 439   /**
 440    * A platform-dependent method to patch a jump instruction that refers
 441    * to this label.
 442    *
 443    * @param branch the location of the instruction to patch
 444    * @param masm the assembler which generated the branch
 445    */
 446   void pd_patch_instruction(address branch, address target);
 447 
 448 };
 449 
 450 #include CPU_HEADER(assembler)
 451 
 452 #endif // SHARE_VM_ASM_ASSEMBLER_HPP
--- EOF ---