| /* Target-dependent code for the TI TMS320C80 (MVP) for GDB, the GNU debugger. |
| Copyright 1996, Free Software Foundation, Inc. |
| |
| This file is part of GDB. |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program; if not, write to the Free Software |
| Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ |
| |
| #include "defs.h" |
| #include "value.h" |
| #include "frame.h" |
| #include "inferior.h" |
| #include "obstack.h" |
| #include "target.h" |
| #include "bfd.h" |
| #include "gdb_string.h" |
| #include "gdbcore.h" |
| #include "symfile.h" |
| |
| /* Function: frame_find_saved_regs |
| Return the frame_saved_regs structure for the frame. |
| Doesn't really work for dummy frames, but it does pass back |
| an empty frame_saved_regs, so I guess that's better than total failure */ |
| |
| void |
| tic80_frame_find_saved_regs (fi, regaddr) |
| struct frame_info *fi; |
| struct frame_saved_regs *regaddr; |
| { |
| memcpy (regaddr, &fi->fsr, sizeof (struct frame_saved_regs)); |
| } |
| |
| /* Function: skip_prologue |
| Find end of function prologue. */ |
| |
| CORE_ADDR |
| tic80_skip_prologue (pc) |
| CORE_ADDR pc; |
| { |
| CORE_ADDR func_addr, func_end; |
| struct symtab_and_line sal; |
| |
| /* See what the symbol table says */ |
| |
| if (find_pc_partial_function (pc, NULL, &func_addr, &func_end)) |
| { |
| sal = find_pc_line (func_addr, 0); |
| |
| if (sal.line != 0 && sal.end < func_end) |
| return sal.end; |
| else |
| /* Either there's no line info, or the line after the prologue is after |
| the end of the function. In this case, there probably isn't a |
| prologue. */ |
| return pc; |
| } |
| |
| /* We can't find the start of this function, so there's nothing we can do. */ |
| return pc; |
| } |
| |
| /* Function: tic80_scan_prologue |
| This function decodes the target function prologue to determine: |
| 1) the size of the stack frame |
| 2) which registers are saved on it |
| 3) the offsets of saved regs |
| 4) the frame size |
| This information is stored in the "extra" fields of the frame_info. */ |
| |
| static void |
| tic80_scan_prologue (fi) |
| struct frame_info *fi; |
| { |
| struct symtab_and_line sal; |
| CORE_ADDR prologue_start, prologue_end, current_pc; |
| |
| /* Assume there is no frame until proven otherwise. */ |
| fi->framereg = SP_REGNUM; |
| fi->framesize = 0; |
| fi->frameoffset = 0; |
| |
| /* this code essentially duplicates skip_prologue, |
| but we need the start address below. */ |
| |
| if (find_pc_partial_function (fi->pc, NULL, &prologue_start, &prologue_end)) |
| { |
| sal = find_pc_line (prologue_start, 0); |
| |
| if (sal.line == 0) /* no line info, use current PC */ |
| if (prologue_start != entry_point_address ()) |
| prologue_end = fi->pc; |
| else |
| return; /* _start has no frame or prologue */ |
| else if (sal.end < prologue_end) /* next line begins after fn end */ |
| prologue_end = sal.end; /* (probably means no prologue) */ |
| } |
| else |
| /* FIXME */ |
| prologue_end = prologue_start + 40; /* We're in the boondocks: allow for */ |
| /* 16 pushes, an add, and "mv fp,sp" */ |
| |
| prologue_end = min (prologue_end, fi->pc); |
| |
| /* Now search the prologue looking for instructions that set up the |
| frame pointer, adjust the stack pointer, and save registers. */ |
| |
| for (current_pc = prologue_start; current_pc < prologue_end; current_pc += 4) |
| { |
| unsigned int insn; |
| int regno; |
| int offset = 0; |
| |
| insn = read_memory_unsigned_integer (current_pc, 4); |
| |
| if ((insn & 0x301000) == 0x301000) /* Long immediate? */ |
| /* FIXME - set offset for long immediate instructions */ |
| current_pc += 4; |
| else |
| { |
| offset = insn & 0x7fff; /* extract 15-bit offset */ |
| if (offset & 0x4000) /* if negative, sign-extend */ |
| offset = -(0x8000 - offset); |
| } |
| |
| if ((insn & 0x7fd0000) == 0x590000) /* st.{w,d} reg, xx(r1) */ |
| { |
| regno = ((insn >> 27) & 0x1f); |
| fi->fsr.regs[regno] = offset; |
| if (insn & 0x8000) /* 64-bit store (st.d)? */ |
| fi->fsr.regs[regno+1] = offset+4; |
| } |
| else if ((insn & 0xffff8000) == 0x086c8000) /* addu xx, r1, r1 */ |
| fi->framesize = -offset; |
| else if ((insn & 0xffff8000) == 0xf06c8000) /* addu xx, r1, r30 */ |
| { |
| fi->framereg = FP_REGNUM; /* fp is now valid */ |
| fi->frameoffset = offset; |
| break; /* end of stack adjustments */ |
| } |
| else if (insn == 0xf03b2001) /* addu r1, r0, r30 */ |
| { |
| fi->framereg = FP_REGNUM; /* fp is now valid */ |
| fi->frameoffset = 0; |
| break; /* end of stack adjustments */ |
| } |
| else |
| /* FIXME - handle long immediate instructions */ |
| break; /* anything else isn't prologue */ |
| } |
| } |
| |
| /* Function: init_extra_frame_info |
| This function actually figures out the frame address for a given pc and |
| sp. This is tricky on the c80 because we sometimes don't use an explicit |
| frame pointer, and the previous stack pointer isn't necessarily recorded |
| on the stack. The only reliable way to get this info is to |
| examine the prologue. */ |
| |
| void |
| tic80_init_extra_frame_info (fi) |
| struct frame_info *fi; |
| { |
| int reg; |
| |
| if (fi->next) |
| fi->pc = FRAME_SAVED_PC (fi->next); |
| |
| /* Because zero is a valid register offset relative to SP, we initialize |
| the offsets to -1 to indicate unused entries. */ |
| for (reg = 0; reg < NUM_REGS; reg++) |
| fi->fsr.regs[reg] = -1; |
| |
| if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame)) |
| { |
| /* We need to setup fi->frame here because run_stack_dummy gets it wrong |
| by assuming it's always FP. */ |
| fi->frame = generic_read_register_dummy (fi->pc, fi->frame, SP_REGNUM); |
| fi->framesize = 0; |
| fi->frameoffset = 0; |
| return; |
| } |
| else |
| { |
| tic80_scan_prologue (fi); |
| |
| if (!fi->next) /* this is the innermost frame? */ |
| fi->frame = read_register (fi->framereg); |
| else /* not the innermost frame */ |
| /* If this function uses FP as the frame register, and the function |
| it called saved the FP, get the saved FP. */ |
| if (fi->framereg == FP_REGNUM && |
| fi->next->fsr.regs[FP_REGNUM] != (unsigned) -1) |
| fi->frame = read_memory_integer (fi->next->fsr.regs[FP_REGNUM], 4); |
| |
| /* Convert SP-relative offsets of saved registers to real addresses. */ |
| for (reg = 0; reg < NUM_REGS; reg++) |
| if (fi->fsr.regs[reg] == (unsigned) -1) |
| fi->fsr.regs[reg] = 0; /* unused entry */ |
| else |
| fi->fsr.regs[reg] += fi->frame - fi->frameoffset; |
| } |
| } |
| |
| /* Function: find_callers_reg |
| Find REGNUM on the stack. Otherwise, it's in an active register. One thing |
| we might want to do here is to check REGNUM against the clobber mask, and |
| somehow flag it as invalid if it isn't saved on the stack somewhere. This |
| would provide a graceful failure mode when trying to get the value of |
| caller-saves registers for an inner frame. */ |
| |
| CORE_ADDR |
| tic80_find_callers_reg (fi, regnum) |
| struct frame_info *fi; |
| int regnum; |
| { |
| for (; fi; fi = fi->next) |
| if (PC_IN_CALL_DUMMY (fi->pc, fi->frame, fi->frame)) |
| return generic_read_register_dummy (fi->pc, fi->frame, regnum); |
| else if (fi->fsr.regs[regnum] != 0) |
| return read_memory_integer (fi->fsr.regs[regnum], |
| REGISTER_RAW_SIZE(regnum)); |
| return read_register (regnum); |
| } |
| |
| /* Function: frame_chain |
| Given a GDB frame, determine the address of the calling function's frame. |
| This will be used to create a new GDB frame struct, and then |
| INIT_EXTRA_FRAME_INFO and INIT_FRAME_PC will be called for the new frame. |
| For c80, we save the frame size when we initialize the frame_info. */ |
| |
| CORE_ADDR |
| tic80_frame_chain (fi) |
| struct frame_info *fi; |
| { |
| CORE_ADDR fn_start, callers_pc, fp; |
| |
| /* is this a dummy frame? */ |
| if (PC_IN_CALL_DUMMY(fi->pc, fi->frame, fi->frame)) |
| return fi->frame; /* dummy frame same as caller's frame */ |
| |
| /* is caller-of-this a dummy frame? */ |
| callers_pc = FRAME_SAVED_PC(fi); /* find out who called us: */ |
| fp = tic80_find_callers_reg (fi, FP_REGNUM); |
| if (PC_IN_CALL_DUMMY(callers_pc, fp, fp)) |
| return fp; /* dummy frame's frame may bear no relation to ours */ |
| |
| if (find_pc_partial_function (fi->pc, 0, &fn_start, 0)) |
| if (fn_start == entry_point_address ()) |
| return 0; /* in _start fn, don't chain further */ |
| |
| if (fi->framereg == FP_REGNUM) |
| return tic80_find_callers_reg (fi, FP_REGNUM); |
| else |
| return fi->frame + fi->framesize; |
| } |
| |
| /* Function: pop_frame |
| Discard from the stack the innermost frame, |
| restoring all saved registers. */ |
| |
| struct frame_info * |
| tic80_pop_frame (frame) |
| struct frame_info *frame; |
| { |
| int regnum; |
| |
| if (PC_IN_CALL_DUMMY (frame->pc, frame->frame, frame->frame)) |
| generic_pop_dummy_frame (); |
| else |
| { |
| for (regnum = 0; regnum < NUM_REGS; regnum++) |
| if (frame->fsr.regs[regnum] != 0) |
| write_register (regnum, |
| read_memory_integer (frame->fsr.regs[regnum], 4)); |
| |
| write_register (PC_REGNUM, FRAME_SAVED_PC (frame)); |
| write_register (SP_REGNUM, read_register (FP_REGNUM)); |
| #if 0 |
| if (read_register (PSW_REGNUM) & 0x80) |
| write_register (SPU_REGNUM, read_register (SP_REGNUM)); |
| else |
| write_register (SPI_REGNUM, read_register (SP_REGNUM)); |
| #endif |
| } |
| flush_cached_frames (); |
| return NULL; |
| } |
| |
| /* Function: frame_saved_pc |
| Find the caller of this frame. We do this by seeing if LR_REGNUM is saved |
| in the stack anywhere, otherwise we get it from the registers. */ |
| |
| CORE_ADDR |
| tic80_frame_saved_pc (fi) |
| struct frame_info *fi; |
| { |
| if (PC_IN_CALL_DUMMY(fi->pc, fi->frame, fi->frame)) |
| return generic_read_register_dummy (fi->pc, fi->frame, PC_REGNUM); |
| else |
| return tic80_find_callers_reg (fi, LR_REGNUM); |
| } |
| |
| /* Function: tic80_push_return_address (pc, sp) |
| Set up the return address for the inferior function call. |
| Necessary for targets that don't actually execute a JSR/BSR instruction |
| (ie. when using an empty CALL_DUMMY) */ |
| |
| CORE_ADDR |
| tic80_push_return_address (pc, sp) |
| CORE_ADDR pc; |
| CORE_ADDR sp; |
| { |
| write_register (LR_REGNUM, CALL_DUMMY_ADDRESS ()); |
| return sp; |
| } |
| |
| |
| /* Function: push_arguments |
| Setup the function arguments for calling a function in the inferior. |
| |
| On the TI C80 architecture, there are six register pairs (R2/R3 to R12/13) |
| which are dedicated for passing function arguments. Up to the first six |
| arguments (depending on size) may go into these registers. |
| The rest go on the stack. |
| |
| Arguments that are smaller than 4 bytes will still take up a whole |
| register or a whole 32-bit word on the stack, and will be |
| right-justified in the register or the stack word. This includes |
| chars, shorts, and small aggregate types. |
| |
| Arguments that are four bytes or less in size are placed in the |
| even-numbered register of a register pair, and the odd-numbered |
| register is not used. |
| |
| Arguments of 8 bytes size (such as floating point doubles) are placed |
| in a register pair. The least significant 32-bit word is placed in |
| the even-numbered register, and the most significant word in the |
| odd-numbered register. |
| |
| Aggregate types with sizes between 4 and 8 bytes are passed |
| entirely on the stack, and are left-justified within the |
| double-word (as opposed to aggregates smaller than 4 bytes |
| which are right-justified). |
| |
| Aggregates of greater than 8 bytes are first copied onto the stack, |
| and then a pointer to the copy is passed in the place of the normal |
| argument (either in a register if available, or on the stack). |
| |
| Functions that must return an aggregate type can return it in the |
| normal return value registers (R2 and R3) if its size is 8 bytes or |
| less. For larger return values, the caller must allocate space for |
| the callee to copy the return value to. A pointer to this space is |
| passed as an implicit first argument, always in R0. */ |
| |
| CORE_ADDR |
| tic80_push_arguments (nargs, args, sp, struct_return, struct_addr) |
| int nargs; |
| value_ptr *args; |
| CORE_ADDR sp; |
| unsigned char struct_return; |
| CORE_ADDR struct_addr; |
| { |
| int stack_offset, stack_alloc; |
| int argreg; |
| int argnum; |
| struct type *type; |
| CORE_ADDR regval; |
| char *val; |
| char valbuf[4]; |
| int len; |
| int odd_sized_struct; |
| int is_struct; |
| |
| /* first force sp to a 4-byte alignment */ |
| sp = sp & ~3; |
| |
| argreg = ARG0_REGNUM; |
| /* The "struct return pointer" pseudo-argument goes in R0 */ |
| if (struct_return) |
| write_register (argreg++, struct_addr); |
| |
| /* Now make sure there's space on the stack */ |
| for (argnum = 0, stack_alloc = 0; |
| argnum < nargs; argnum++) |
| stack_alloc += ((TYPE_LENGTH(VALUE_TYPE(args[argnum])) + 3) & ~3); |
| sp -= stack_alloc; /* make room on stack for args */ |
| |
| |
| /* Now load as many as possible of the first arguments into |
| registers, and push the rest onto the stack. There are 16 bytes |
| in four registers available. Loop thru args from first to last. */ |
| |
| argreg = ARG0_REGNUM; |
| for (argnum = 0, stack_offset = 0; argnum < nargs; argnum++) |
| { |
| type = VALUE_TYPE (args[argnum]); |
| len = TYPE_LENGTH (type); |
| memset (valbuf, 0, sizeof (valbuf)); |
| val = (char *) VALUE_CONTENTS (args[argnum]); |
| |
| /* FIXME -- tic80 can take doubleword arguments in register pairs */ |
| is_struct = (type->code == TYPE_CODE_STRUCT); |
| odd_sized_struct = 0; |
| |
| if (! is_struct) |
| { |
| if (len < 4) |
| { /* value gets right-justified in the register or stack word */ |
| memcpy (valbuf + (4 - len), val, len); |
| val = valbuf; |
| } |
| if (len > 4 && (len & 3) != 0) |
| odd_sized_struct = 1; /* such structs go entirely on stack */ |
| } |
| else |
| { |
| /* Structs are always passed by reference. */ |
| write_register (argreg, sp + stack_offset); |
| argreg ++; |
| } |
| |
| while (len > 0) |
| { |
| if (is_struct || argreg > ARGLAST_REGNUM || odd_sized_struct) |
| { /* must go on the stack */ |
| write_memory (sp + stack_offset, val, 4); |
| stack_offset += 4; |
| } |
| /* NOTE WELL!!!!! This is not an "else if" clause!!! |
| That's because some things get passed on the stack |
| AND in the registers! */ |
| if (!is_struct && argreg <= ARGLAST_REGNUM) |
| { /* there's room in a register */ |
| regval = extract_address (val, REGISTER_RAW_SIZE(argreg)); |
| write_register (argreg, regval); |
| argreg += 2; /* FIXME -- what about doubleword args? */ |
| } |
| /* Store the value 4 bytes at a time. This means that things |
| larger than 4 bytes may go partly in registers and partly |
| on the stack. */ |
| len -= REGISTER_RAW_SIZE(argreg); |
| val += REGISTER_RAW_SIZE(argreg); |
| } |
| } |
| return sp; |
| } |
| |
| /* Function: tic80_write_sp |
| Because SP is really a read-only register that mirrors either SPU or SPI, |
| we must actually write one of those two as well, depending on PSW. */ |
| |
| void |
| tic80_write_sp (val) |
| CORE_ADDR val; |
| { |
| #if 0 |
| unsigned long psw = read_register (PSW_REGNUM); |
| |
| if (psw & 0x80) /* stack mode: user or interrupt */ |
| write_register (SPU_REGNUM, val); |
| else |
| write_register (SPI_REGNUM, val); |
| #endif |
| write_register (SP_REGNUM, val); |
| } |
| |
| void |
| _initialize_tic80_tdep () |
| { |
| tm_print_insn = print_insn_tic80; |
| } |
| |