gcc/ada/5gmastop.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                     SYSTEM.MACHINE_STATE_OPERATIONS                      --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                         (Version for IRIX/MIPS)                          --
   9 --                                                                          --
  10 --          Copyright (C) 1999-2004 Free Software Foundation, Inc.          --
  11 --                                                                          --
  12 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  13 -- terms of the  GNU General Public License as published  by the Free Soft- --
  14 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  15 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  16 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  17 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  18 -- for  more details.  You should have  received  a copy of the GNU General --
  19 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  20 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  21 -- MA 02111-1307, USA.                                                      --
  22 --                                                                          --
  23 -- As a special exception,  if other files  instantiate  generics from this --
  24 -- unit, or you link  this unit with other files  to produce an executable, --
  25 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  26 -- covered  by the  GNU  General  Public  License.  This exception does not --
  27 -- however invalidate  any other reasons why  the executable file  might be --
  28 -- covered by the  GNU Public License.                                      --
  29 --                                                                          --
  30 -- GNAT was originally developed  by the GNAT team at  New York University. --
  31 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  32 --                                                                          --
  33 ------------------------------------------------------------------------------
  34
  35 --  This version of Ada.Exceptions.Machine_State_Operations is for use on
  36 --  SGI Irix systems. By means of compile time conditional calculations, it
  37 --  can handle both n32/n64 and o32 modes.
  38
  39 with System.Machine_Code; use System.Machine_Code;
  40 with System.Memory;
  41 with System.Soft_Links; use System.Soft_Links;
  42 with Unchecked_Conversion;
  43
  44 package body System.Machine_State_Operations is
  45
  46    use System.Storage_Elements;
  47    use System.Exceptions;
  48
  49    --  The exc_unwind function in libexc operats on a Sigcontext
  50
  51    --  Type sigcontext_t is defined in /usr/include/sys/signal.h.
  52    --  We define an equivalent Ada type here. From the comments in
  53    --  signal.h:
  54
  55    --    sigcontext is not part of the ABI - so this version is used to
  56    --    handle 32 and 64 bit applications - it is a constant size regardless
  57    --    of compilation mode, and always returns 64 bit register values
  58
  59    type Uns32 is mod 2 ** 32;
  60    type Uns64 is mod 2 ** 64;
  61
  62    type Uns32_Ptr is access all Uns32;
  63    type Uns64_Array is array (Integer range <>) of Uns64;
  64
  65    type Reg_Array is array (0 .. 31) of Uns64;
  66
  67    type Sigcontext is record
  68       SC_Regmask           : Uns32;          --  0
  69       SC_Status            : Uns32;          --  4
  70       SC_PC                : Uns64;          --  8
  71       SC_Regs              : Reg_Array;      --  16
  72       SC_Fpregs            : Reg_Array;      --  272
  73       SC_Ownedfp           : Uns32;          --  528
  74       SC_Fpc_Csr           : Uns32;          --  532
  75       SC_Fpc_Eir           : Uns32;          --  536
  76       SC_Ssflags           : Uns32;          --  540
  77       SC_Mdhi              : Uns64;          --  544
  78       SC_Mdlo              : Uns64;          --  552
  79       SC_Cause             : Uns64;          --  560
  80       SC_Badvaddr          : Uns64;          --  568
  81       SC_Triggersave       : Uns64;          --  576
  82       SC_Sigset            : Uns64;          --  584
  83       SC_Fp_Rounded_Result : Uns64;          --  592
  84       SC_Pancake           : Uns64_Array (0 .. 5);
  85       SC_Pad               : Uns64_Array (0 .. 26);
  86    end record;
  87
  88    type Sigcontext_Ptr is access all Sigcontext;
  89
  90    SC_Regs_Pos   : constant String := "16";
  91    SC_Fpregs_Pos : constant String := "272";
  92    --  Byte offset of the Integer and Floating Point register save areas
  93    --  within the Sigcontext.
  94
  95    function To_Sigcontext_Ptr is
  96      new Unchecked_Conversion (Machine_State, Sigcontext_Ptr);
  97
  98    type Addr_Int is mod 2 ** Long_Integer'Size;
  99    --  An unsigned integer type whose size is the same as System.Address.
 100    --  We rely on the fact that Long_Integer'Size = System.Address'Size in
 101    --  all ABIs.  Type Addr_Int can be converted to Uns64.
 102
 103    function To_Code_Loc is new Unchecked_Conversion (Addr_Int, Code_Loc);
 104    function To_Addr_Int is new Unchecked_Conversion (System.Address, Addr_Int);
 105    function To_Uns32_Ptr is new Unchecked_Conversion (Addr_Int, Uns32_Ptr);
 106
 107    --------------------------------
 108    -- ABI-Dependent Declarations --
 109    --------------------------------
 110
 111    o32  : constant Boolean := System.Word_Size = 32;
 112    n32  : constant Boolean := System.Word_Size = 64;
 113    o32n : constant Natural := Boolean'Pos (o32);
 114    n32n : constant Natural := Boolean'Pos (n32);
 115    --  Flags to indicate which ABI is in effect for this compilation. For the
 116    --  purposes of this unit, the n32 and n64 ABI's are identical.
 117
 118    LSC : constant Character := Character'Val (o32n * Character'Pos ('w') +
 119                                               n32n * Character'Pos ('d'));
 120    --  This is 'w' for o32, and 'd' for n32/n64, used for constructing the
 121    --  load/store instructions used to save/restore machine instructions.
 122
 123    Roff : constant Character := Character'Val (o32n * Character'Pos ('4') +
 124                                                n32n * Character'Pos (' '));
 125    --  Offset from first byte of a __uint64 register save location where
 126    --  the register value is stored.  For n32/64 we store the entire 64
 127    --  bit register into the uint64.  For o32, only 32 bits are stored
 128    --  at an offset of 4 bytes.
 129
 130    procedure Update_GP (Scp : Sigcontext_Ptr);
 131
 132    ---------------
 133    -- Update_GP --
 134    ---------------
 135
 136    procedure Update_GP (Scp : Sigcontext_Ptr) is
 137
 138       type F_op  is mod 2 ** 6;
 139       type F_reg is mod 2 ** 5;
 140       type F_imm is new Short_Integer;
 141
 142       type I_Type is record
 143          op    : F_op;
 144          rs    : F_reg;
 145          rt    : F_reg;
 146          imm   : F_imm;
 147       end record;
 148
 149       pragma Pack (I_Type);
 150       for I_Type'Size use 32;
 151
 152       type I_Type_Ptr is access all I_Type;
 153
 154       LW : constant F_op := 2#100011#;
 155       Reg_GP : constant := 28;
 156
 157       type Address_Int is mod 2 ** Standard'Address_Size;
 158       function To_I_Type_Ptr is new
 159         Unchecked_Conversion (Address_Int, I_Type_Ptr);
 160
 161       Ret_Ins : constant I_Type_Ptr := To_I_Type_Ptr (Address_Int (Scp.SC_PC));
 162       GP_Ptr  : Uns32_Ptr;
 163
 164    begin
 165       if Ret_Ins.op = LW and then Ret_Ins.rt = Reg_GP then
 166          GP_Ptr := To_Uns32_Ptr
 167            (Addr_Int (Scp.SC_Regs (Integer (Ret_Ins.rs)))
 168             + Addr_Int (Ret_Ins.imm));
 169          Scp.SC_Regs (Reg_GP) := Uns64 (GP_Ptr.all);
 170       end if;
 171    end Update_GP;
 172
 173    ----------------------------
 174    -- Allocate_Machine_State --
 175    ----------------------------
 176
 177    function Allocate_Machine_State return Machine_State is
 178    begin
 179       return Machine_State
 180         (Memory.Alloc (Sigcontext'Max_Size_In_Storage_Elements));
 181    end Allocate_Machine_State;
 182
 183    -------------------
 184    -- Enter_Handler --
 185    -------------------
 186
 187    procedure Enter_Handler (M : Machine_State; Handler : Handler_Loc) is
 188       pragma Warnings (Off, M);
 189       pragma Warnings (Off, Handler);
 190
 191       LOADI : constant String (1 .. 2) := 'l' & LSC;
 192       --  This is "lw" in o32 mode, and "ld" in n32/n64 mode
 193
 194       LOADF : constant String (1 .. 4) := 'l' & LSC & "c1";
 195       --  This is "lwc1" in o32 mode and "ldc1" in n32/n64 mode
 196
 197    begin
 198       --  Restore integer registers from machine state. Note that we know
 199       --  that $4 points to M, and $5 points to Handler, since this is
 200       --  the standard calling sequence
 201
 202       Asm (LOADI & " $16,  16*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 203       Asm (LOADI & " $17,  17*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 204       Asm (LOADI & " $18,  18*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 205       Asm (LOADI & " $19,  19*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 206       Asm (LOADI & " $20,  20*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 207       Asm (LOADI & " $21,  21*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 208       Asm (LOADI & " $22,  22*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 209       Asm (LOADI & " $23,  23*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 210       Asm (LOADI & " $24,  24*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 211       Asm (LOADI & " $25,  25*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 212       Asm (LOADI & " $26,  26*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 213       Asm (LOADI & " $27,  27*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 214       Asm (LOADI & " $28,  28*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 215       Asm (LOADI & " $29,  29*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 216       Asm (LOADI & " $30,  30*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 217       Asm (LOADI & " $31,  31*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 218
 219       --  Restore floating-point registers from machine state
 220
 221       Asm (LOADF & " $f16, 16*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 222       Asm (LOADF & " $f17, 17*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 223       Asm (LOADF & " $f18, 18*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 224       Asm (LOADF & " $f19, 19*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 225       Asm (LOADF & " $f20, 20*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 226       Asm (LOADF & " $f21, 21*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 227       Asm (LOADF & " $f22, 22*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 228       Asm (LOADF & " $f23, 23*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 229       Asm (LOADF & " $f24, 24*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 230       Asm (LOADF & " $f25, 25*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 231       Asm (LOADF & " $f26, 26*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 232       Asm (LOADF & " $f27, 27*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 233       Asm (LOADF & " $f28, 28*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 234       Asm (LOADF & " $f29, 29*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 235       Asm (LOADF & " $f30, 30*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 236       Asm (LOADF & " $f31, 31*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 237
 238       --  Jump directly to the handler
 239
 240       Asm ("jr  $5");
 241    end Enter_Handler;
 242
 243    ----------------
 244    -- Fetch_Code --
 245    ----------------
 246
 247    function Fetch_Code (Loc : Code_Loc) return Code_Loc is
 248    begin
 249       return Loc;
 250    end Fetch_Code;
 251
 252    ------------------------
 253    -- Free_Machine_State --
 254    ------------------------
 255
 256    procedure Free_Machine_State (M : in out Machine_State) is
 257    begin
 258       Memory.Free (Address (M));
 259       M := Machine_State (Null_Address);
 260    end Free_Machine_State;
 261
 262    ------------------
 263    -- Get_Code_Loc --
 264    ------------------
 265
 266    function Get_Code_Loc (M : Machine_State) return Code_Loc is
 267       SC : constant Sigcontext_Ptr := To_Sigcontext_Ptr (M);
 268    begin
 269       return To_Code_Loc (Addr_Int (SC.SC_PC));
 270    end Get_Code_Loc;
 271
 272    --------------------------
 273    -- Machine_State_Length --
 274    --------------------------
 275
 276    function Machine_State_Length return Storage_Offset is
 277    begin
 278       return Sigcontext'Max_Size_In_Storage_Elements;
 279    end Machine_State_Length;
 280
 281    ---------------
 282    -- Pop_Frame --
 283    ---------------
 284
 285    procedure Pop_Frame
 286      (M    : Machine_State;
 287       Info : Subprogram_Info_Type)
 288    is
 289       pragma Warnings (Off, Info);
 290
 291       Scp : constant Sigcontext_Ptr := To_Sigcontext_Ptr (M);
 292
 293       procedure Exc_Unwind (Scp : Sigcontext_Ptr; Fde : Long_Integer := 0);
 294       pragma Import (C, Exc_Unwind, "exc_unwind");
 295
 296       --  ??? Calling exc_unwind in the current setup does not work and
 297       --  triggers the emission of system warning messages. Why it does
 298       --  not work remains to be investigated. Part of the problem is
 299       --  probably a section naming issue (e.g. .eh_frame/.debug_frame).
 300
 301       --  Instead of letting the call take place for nothing and emit
 302       --  messages we don't expect, we just arrange things to pretend it
 303       --  occurred and failed.
 304
 305       --  ??? Until this is fixed, we shall document that the backtrace
 306       --  computation facility does not work, and we inhibit the pragma below
 307       --  because we arrange for the call not to be emitted and the linker
 308       --  complains when a library is linked in but resolves nothing.
 309
 310       --  pragma Linker_Options ("-lexc");
 311
 312    begin
 313       --  exc_unwind is apparently not thread-safe under IRIX, so protect it
 314       --  against race conditions within the GNAT run time.
 315       --  ??? Note that we might want to use a fine grained lock here since
 316       --  Lock_Task is used in many other places.
 317
 318       Lock_Task.all;
 319
 320       if False then
 321          Exc_Unwind (Scp);
 322       else
 323          Scp.SC_PC := 0;
 324       end if;
 325
 326       Unlock_Task.all;
 327
 328       if Scp.SC_PC = 0 or else Scp.SC_PC = 1 then
 329
 330          --  A return value of 0 or 1 means exc_unwind couldn't find a parent
 331          --  frame. Propagate_Exception expects a zero return address to
 332          --  indicate TOS.
 333
 334          Scp.SC_PC := 0;
 335
 336       else
 337          --  Set the GP to restore to the caller value (not callee value)
 338          --  This is done only in o32 mode. In n32/n64 mode, GP is a normal
 339          --  callee save register
 340
 341          if o32 then
 342             Update_GP (Scp);
 343          end if;
 344
 345          --  Adjust the return address to the call site, not the
 346          --  instruction following the branch delay slot.  This may
 347          --  be necessary if the last instruction of a pragma No_Return
 348          --  subprogram is a call. The first instruction following the
 349          --  delay slot may be the start of another subprogram. We back
 350          --  off the address by 8, which points safely into the middle
 351          --  of the generated subprogram code, avoiding end effects.
 352
 353          Scp.SC_PC := Scp.SC_PC - 8;
 354       end if;
 355    end Pop_Frame;
 356
 357    -----------------------
 358    -- Set_Machine_State --
 359    -----------------------
 360
 361    procedure Set_Machine_State (M : Machine_State) is
 362
 363       STOREI : constant String (1 .. 2) := 's' & LSC;
 364       --  This is "sw" in o32 mode, and "sd" in n32 mode
 365
 366       STOREF : constant String (1 .. 4) := 's' & LSC & "c1";
 367       --  This is "swc1" in o32 mode and "sdc1" in n32 mode
 368
 369       Scp : Sigcontext_Ptr;
 370
 371    begin
 372       --  Save the integer registers. Note that we know that $4 points
 373       --  to M, since that is where the first parameter is passed.
 374       --  Restore integer registers from machine state. Note that we know
 375       --  that $4 points to M since this is the standard calling sequence
 376
 377       <<Past_Prolog>>
 378
 379       Asm (STOREI & " $16,  16*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 380       Asm (STOREI & " $17,  17*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 381       Asm (STOREI & " $18,  18*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 382       Asm (STOREI & " $19,  19*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 383       Asm (STOREI & " $20,  20*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 384       Asm (STOREI & " $21,  21*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 385       Asm (STOREI & " $22,  22*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 386       Asm (STOREI & " $23,  23*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 387       Asm (STOREI & " $24,  24*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 388       Asm (STOREI & " $25,  25*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 389       Asm (STOREI & " $26,  26*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 390       Asm (STOREI & " $27,  27*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 391       Asm (STOREI & " $28,  28*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 392       Asm (STOREI & " $29,  29*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 393       Asm (STOREI & " $30,  30*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 394       Asm (STOREI & " $31,  31*8+" & Roff & "+" & SC_Regs_Pos & "($4)");
 395
 396       --  Restore floating-point registers from machine state
 397
 398       Asm (STOREF & " $f16, 16*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 399       Asm (STOREF & " $f17, 17*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 400       Asm (STOREF & " $f18, 18*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 401       Asm (STOREF & " $f19, 19*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 402       Asm (STOREF & " $f20, 20*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 403       Asm (STOREF & " $f21, 21*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 404       Asm (STOREF & " $f22, 22*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 405       Asm (STOREF & " $f23, 23*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 406       Asm (STOREF & " $f24, 24*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 407       Asm (STOREF & " $f25, 25*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 408       Asm (STOREF & " $f26, 26*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 409       Asm (STOREF & " $f27, 27*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 410       Asm (STOREF & " $f28, 28*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 411       Asm (STOREF & " $f29, 29*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 412       Asm (STOREF & " $f30, 30*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 413       Asm (STOREF & " $f31, 31*8+" & Roff & "+" & SC_Fpregs_Pos & "($4)");
 414
 415       --  Set the PC value for the context to a location after the
 416       --  prolog has been executed.
 417
 418       Scp := To_Sigcontext_Ptr (M);
 419       Scp.SC_PC := Uns64 (To_Addr_Int (Past_Prolog'Address));
 420
 421       --  We saved the state *inside* this routine, but what we want is
 422       --  the state at the call site. So we need to do one pop operation.
 423       --  This pop operation will properly set the PC value in the machine
 424       --  state, so there is no need to save PC in the above code.
 425
 426       Pop_Frame (M, Set_Machine_State'Address);
 427    end Set_Machine_State;
 428
 429    ------------------------------
 430    -- Set_Signal_Machine_State --
 431    ------------------------------
 432
 433    procedure Set_Signal_Machine_State
 434      (M       : Machine_State;
 435       Context : System.Address)
 436    is
 437       pragma Warnings (Off, M);
 438       pragma Warnings (Off, Context);
 439
 440    begin
 441       null;
 442    end Set_Signal_Machine_State;
 443
 444 end System.Machine_State_Operations;