/* Cache and manage frames for GDB, the GNU debugger. Copyright 1986, 1987, 1989, 1991, 1994, 1995, 1996, 1998, 2000, 2001, 2002 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 "frame.h" #include "target.h" #include "value.h" #include "inferior.h" /* for inferior_ptid */ #include "regcache.h" #include "gdb_assert.h" #include "gdb_string.h" #include "builtin-regs.h" #include "gdb_obstack.h" #include "dummy-frame.h" #include "gdbcore.h" #include "annotate.h" #include "language.h" /* Return a frame uniq ID that can be used to, later, re-find the frame. */ struct frame_id get_frame_id (struct frame_info *fi) { if (fi == NULL) { return null_frame_id; } else { struct frame_id id; id.base = fi->frame; id.pc = fi->pc; return id; } } const struct frame_id null_frame_id; /* All zeros. */ struct frame_id frame_id_build (CORE_ADDR base, CORE_ADDR func_or_pc) { struct frame_id id; id.base = base; id.pc = func_or_pc; return id; } int frame_id_p (struct frame_id l) { /* The .func can be NULL but the .base cannot. */ return (l.base != 0); } int frame_id_eq (struct frame_id l, struct frame_id r) { /* If .base is different, the frames are different. */ if (l.base != r.base) return 0; /* Add a test to check that the frame ID's are for the same function here. */ return 1; } int frame_id_inner (struct frame_id l, struct frame_id r) { /* Only return non-zero when strictly inner than. Note that, per comment in "frame.h", there is some fuzz here. Frameless functions are not strictly inner than (same .base but different .func). */ return INNER_THAN (l.base, r.base); } struct frame_info * frame_find_by_id (struct frame_id id) { struct frame_info *frame; /* ZERO denotes the null frame, let the caller decide what to do about it. Should it instead return get_current_frame()? */ if (!frame_id_p (id)) return NULL; for (frame = get_current_frame (); frame != NULL; frame = get_prev_frame (frame)) { struct frame_id this = get_frame_id (frame); if (frame_id_eq (id, this)) /* An exact match. */ return frame; if (frame_id_inner (id, this)) /* Gone to far. */ return NULL; /* Either, we're not yet gone far enough out along the frame chain (inner(this,id), or we're comparing frameless functions (same .base, different .func, no test available). Struggle on until we've definitly gone to far. */ } return NULL; } CORE_ADDR frame_pc_unwind (struct frame_info *frame) { if (!frame->pc_unwind_cache_p) { frame->pc_unwind_cache = frame->pc_unwind (frame, &frame->unwind_cache); frame->pc_unwind_cache_p = 1; } return frame->pc_unwind_cache; } void frame_register_unwind (struct frame_info *frame, int regnum, int *optimizedp, enum lval_type *lvalp, CORE_ADDR *addrp, int *realnump, void *bufferp) { struct frame_unwind_cache *cache; /* Require all but BUFFERP to be valid. A NULL BUFFERP indicates that the value proper does not need to be fetched. */ gdb_assert (optimizedp != NULL); gdb_assert (lvalp != NULL); gdb_assert (addrp != NULL); gdb_assert (realnump != NULL); /* gdb_assert (bufferp != NULL); */ /* NOTE: cagney/2002-04-14: It would be nice if, instead of a special case, there was always an inner frame dedicated to the hardware registers. Unfortunatly, there is too much unwind code around that looks up/down the frame chain while making the assumption that each frame level is using the same unwind code. */ if (frame == NULL) { /* We're in the inner-most frame, get the value direct from the register cache. */ *optimizedp = 0; *lvalp = lval_register; /* ULGH! Code uses the offset into the raw register byte array as a way of identifying a register. */ *addrp = REGISTER_BYTE (regnum); /* Should this code test ``register_cached (regnum) < 0'' and do something like set realnum to -1 when the register isn't available? */ *realnump = regnum; if (bufferp) deprecated_read_register_gen (regnum, bufferp); return; } /* Ask this frame to unwind its register. */ frame->register_unwind (frame, &frame->unwind_cache, regnum, optimizedp, lvalp, addrp, realnump, bufferp); } void frame_register (struct frame_info *frame, int regnum, int *optimizedp, enum lval_type *lvalp, CORE_ADDR *addrp, int *realnump, void *bufferp) { /* Require all but BUFFERP to be valid. A NULL BUFFERP indicates that the value proper does not need to be fetched. */ gdb_assert (optimizedp != NULL); gdb_assert (lvalp != NULL); gdb_assert (addrp != NULL); gdb_assert (realnump != NULL); /* gdb_assert (bufferp != NULL); */ /* Ulgh! Old code that, for lval_register, sets ADDRP to the offset of the register in the register cache. It should instead return the REGNUM corresponding to that register. Translate the . */ if (GET_SAVED_REGISTER_P ()) { GET_SAVED_REGISTER (bufferp, optimizedp, addrp, frame, regnum, lvalp); /* Compute the REALNUM if the caller wants it. */ if (*lvalp == lval_register) { int regnum; for (regnum = 0; regnum < NUM_REGS + NUM_PSEUDO_REGS; regnum++) { if (*addrp == register_offset_hack (current_gdbarch, regnum)) { *realnump = regnum; return; } } internal_error (__FILE__, __LINE__, "Failed to compute the register number corresponding" " to 0x%s", paddr_d (*addrp)); } *realnump = -1; return; } /* Reached the the bottom (youngest, inner most) of the frame chain (youngest, inner most) frame, go direct to the hardware register cache (do not pass go, do not try to cache the value, ...). The unwound value would have been cached in frame->next but that doesn't exist. This doesn't matter as the hardware register cache is stopping any unnecessary accesses to the target. */ /* NOTE: cagney/2002-04-14: It would be nice if, instead of a special case, there was always an inner frame dedicated to the hardware registers. Unfortunatly, there is too much unwind code around that looks up/down the frame chain while making the assumption that each frame level is using the same unwind code. */ if (frame == NULL) frame_register_unwind (NULL, regnum, optimizedp, lvalp, addrp, realnump, bufferp); else frame_register_unwind (frame->next, regnum, optimizedp, lvalp, addrp, realnump, bufferp); } void frame_unwind_signed_register (struct frame_info *frame, int regnum, LONGEST *val) { int optimized; CORE_ADDR addr; int realnum; enum lval_type lval; void *buf = alloca (MAX_REGISTER_RAW_SIZE); frame_register_unwind (frame, regnum, &optimized, &lval, &addr, &realnum, buf); (*val) = extract_signed_integer (buf, REGISTER_VIRTUAL_SIZE (regnum)); } void frame_unwind_unsigned_register (struct frame_info *frame, int regnum, ULONGEST *val) { int optimized; CORE_ADDR addr; int realnum; enum lval_type lval; void *buf = alloca (MAX_REGISTER_RAW_SIZE); frame_register_unwind (frame, regnum, &optimized, &lval, &addr, &realnum, buf); (*val) = extract_unsigned_integer (buf, REGISTER_VIRTUAL_SIZE (regnum)); } void frame_read_unsigned_register (struct frame_info *frame, int regnum, ULONGEST *val) { /* NOTE: cagney/2002-10-31: There is a bit of dogma here - there is always a frame. Both this, and the equivalent frame_read_signed_register() function, can only be called with a valid frame. If, for some reason, this function is called without a frame then the problem isn't here, but rather in the caller. It should of first created a frame and then passed that in. */ /* NOTE: cagney/2002-10-31: As a side bar, keep in mind that the ``current_frame'' should not be treated as a special case. While ``get_next_frame (current_frame) == NULL'' currently holds, it should, as far as possible, not be relied upon. In the future, ``get_next_frame (current_frame)'' may instead simply return a normal frame object that simply always gets register values from the register cache. Consequently, frame code should try to avoid tests like ``if get_next_frame() == NULL'' and instead just rely on recursive frame calls (like the below code) when manipulating a frame chain. */ gdb_assert (frame != NULL); frame_unwind_unsigned_register (get_next_frame (frame), regnum, val); } void frame_read_signed_register (struct frame_info *frame, int regnum, LONGEST *val) { /* See note in frame_read_unsigned_register(). */ gdb_assert (frame != NULL); frame_unwind_signed_register (get_next_frame (frame), regnum, val); } static void generic_unwind_get_saved_register (char *raw_buffer, int *optimizedp, CORE_ADDR *addrp, struct frame_info *frame, int regnum, enum lval_type *lvalp) { int optimizedx; CORE_ADDR addrx; int realnumx; enum lval_type lvalx; if (!target_has_registers) error ("No registers."); /* Keep things simple, ensure that all the pointers (except valuep) are non NULL. */ if (optimizedp == NULL) optimizedp = &optimizedx; if (lvalp == NULL) lvalp = &lvalx; if (addrp == NULL) addrp = &addrx; /* Reached the the bottom (youngest, inner most) of the frame chain (youngest, inner most) frame, go direct to the hardware register cache (do not pass go, do not try to cache the value, ...). The unwound value would have been cached in frame->next but that doesn't exist. This doesn't matter as the hardware register cache is stopping any unnecessary accesses to the target. */ /* NOTE: cagney/2002-04-14: It would be nice if, instead of a special case, there was always an inner frame dedicated to the hardware registers. Unfortunatly, there is too much unwind code around that looks up/down the frame chain while making the assumption that each frame level is using the same unwind code. */ if (frame == NULL) frame_register_unwind (NULL, regnum, optimizedp, lvalp, addrp, &realnumx, raw_buffer); else frame_register_unwind (frame->next, regnum, optimizedp, lvalp, addrp, &realnumx, raw_buffer); } void get_saved_register (char *raw_buffer, int *optimized, CORE_ADDR *addrp, struct frame_info *frame, int regnum, enum lval_type *lval) { if (GET_SAVED_REGISTER_P ()) { GET_SAVED_REGISTER (raw_buffer, optimized, addrp, frame, regnum, lval); return; } generic_unwind_get_saved_register (raw_buffer, optimized, addrp, frame, regnum, lval); } /* frame_register_read () Find and return the value of REGNUM for the specified stack frame. The number of bytes copied is REGISTER_RAW_SIZE (REGNUM). Returns 0 if the register value could not be found. */ int frame_register_read (struct frame_info *frame, int regnum, void *myaddr) { int optimized; enum lval_type lval; CORE_ADDR addr; int realnum; frame_register (frame, regnum, &optimized, &lval, &addr, &realnum, myaddr); /* FIXME: cagney/2002-05-15: This test, is just bogus. It indicates that the target failed to supply a value for a register because it was "not available" at this time. Problem is, the target still has the register and so get saved_register() may be returning a value saved on the stack. */ if (register_cached (regnum) < 0) return 0; /* register value not available */ return !optimized; } /* Map between a frame register number and its name. A frame register space is a superset of the cooked register space --- it also includes builtin registers. */ int frame_map_name_to_regnum (const char *name, int len) { int i; /* Search register name space. */ for (i = 0; i < NUM_REGS + NUM_PSEUDO_REGS; i++) if (REGISTER_NAME (i) && len == strlen (REGISTER_NAME (i)) && strncmp (name, REGISTER_NAME (i), len) == 0) { return i; } /* Try builtin registers. */ i = builtin_reg_map_name_to_regnum (name, len); if (i >= 0) { /* A builtin register doesn't fall into the architecture's register range. */ gdb_assert (i >= NUM_REGS + NUM_PSEUDO_REGS); return i; } return -1; } const char * frame_map_regnum_to_name (int regnum) { if (regnum < 0) return NULL; if (regnum < NUM_REGS + NUM_PSEUDO_REGS) return REGISTER_NAME (regnum); return builtin_reg_map_regnum_to_name (regnum); } /* Info about the innermost stack frame (contents of FP register) */ static struct frame_info *current_frame; /* Cache for frame addresses already read by gdb. Valid only while inferior is stopped. Control variables for the frame cache should be local to this module. */ static struct obstack frame_cache_obstack; void * frame_obstack_alloc (unsigned long size) { return obstack_alloc (&frame_cache_obstack, size); } void frame_saved_regs_zalloc (struct frame_info *fi) { fi->saved_regs = (CORE_ADDR *) frame_obstack_alloc (SIZEOF_FRAME_SAVED_REGS); memset (fi->saved_regs, 0, SIZEOF_FRAME_SAVED_REGS); } /* Return the innermost (currently executing) stack frame. */ struct frame_info * get_current_frame (void) { if (current_frame == NULL) { if (target_has_stack) current_frame = create_new_frame (read_fp (), read_pc ()); else error ("No stack."); } return current_frame; } void set_current_frame (struct frame_info *frame) { current_frame = frame; } /* The "selected" stack frame is used by default for local and arg access. May be zero, for no selected frame. */ struct frame_info *deprecated_selected_frame; /* Return the selected frame. Always non-null (unless there isn't an inferior sufficient for creating a frame) in which case an error is thrown. */ struct frame_info * get_selected_frame (void) { if (deprecated_selected_frame == NULL) /* Hey! Don't trust this. It should really be re-finding the last selected frame of the currently selected thread. This, though, is better than nothing. */ select_frame (get_current_frame ()); /* There is always a frame. */ gdb_assert (deprecated_selected_frame != NULL); return deprecated_selected_frame; } /* Select frame FI (or NULL - to invalidate the current frame). */ void select_frame (struct frame_info *fi) { register struct symtab *s; deprecated_selected_frame = fi; /* NOTE: cagney/2002-05-04: FI can be NULL. This occures when the frame is being invalidated. */ if (selected_frame_level_changed_hook) selected_frame_level_changed_hook (frame_relative_level (fi)); /* FIXME: kseitz/2002-08-28: It would be nice to call selected_frame_level_changed_event right here, but due to limitations in the current interfaces, we would end up flooding UIs with events because select_frame is used extensively internally. Once we have frame-parameterized frame (and frame-related) commands, the event notification can be moved here, since this function will only be called when the users selected frame is being changed. */ /* Ensure that symbols for this frame are read in. Also, determine the source language of this frame, and switch to it if desired. */ if (fi) { s = find_pc_symtab (fi->pc); if (s && s->language != current_language->la_language && s->language != language_unknown && language_mode == language_mode_auto) { set_language (s->language); } } } /* Return the register saved in the simplistic ``saved_regs'' cache. If the value isn't here AND a value is needed, try the next inner most frame. */ static void frame_saved_regs_register_unwind (struct frame_info *frame, void **cache, int regnum, int *optimizedp, enum lval_type *lvalp, CORE_ADDR *addrp, int *realnump, void *bufferp) { /* There is always a frame at this point. And THIS is the frame we're interested in. */ gdb_assert (frame != NULL); /* If we're using generic dummy frames, we'd better not be in a call dummy. (generic_call_dummy_register_unwind ought to have been called instead.) */ gdb_assert (!(DEPRECATED_USE_GENERIC_DUMMY_FRAMES && (get_frame_type (frame) == DUMMY_FRAME))); /* Load the saved_regs register cache. */ if (frame->saved_regs == NULL) FRAME_INIT_SAVED_REGS (frame); if (frame->saved_regs != NULL && frame->saved_regs[regnum] != 0) { if (regnum == SP_REGNUM) { /* SP register treated specially. */ *optimizedp = 0; *lvalp = not_lval; *addrp = 0; *realnump = -1; if (bufferp != NULL) store_address (bufferp, REGISTER_RAW_SIZE (regnum), frame->saved_regs[regnum]); } else { /* Any other register is saved in memory, fetch it but cache a local copy of its value. */ *optimizedp = 0; *lvalp = lval_memory; *addrp = frame->saved_regs[regnum]; *realnump = -1; if (bufferp != NULL) { #if 1 /* Save each register value, as it is read in, in a frame based cache. */ void **regs = (*cache); if (regs == NULL) { int sizeof_cache = ((NUM_REGS + NUM_PSEUDO_REGS) * sizeof (void *)); regs = frame_obstack_alloc (sizeof_cache); memset (regs, 0, sizeof_cache); (*cache) = regs; } if (regs[regnum] == NULL) { regs[regnum] = frame_obstack_alloc (REGISTER_RAW_SIZE (regnum)); read_memory (frame->saved_regs[regnum], regs[regnum], REGISTER_RAW_SIZE (regnum)); } memcpy (bufferp, regs[regnum], REGISTER_RAW_SIZE (regnum)); #else /* Read the value in from memory. */ read_memory (frame->saved_regs[regnum], bufferp, REGISTER_RAW_SIZE (regnum)); #endif } } return; } /* No luck, assume this and the next frame have the same register value. If a value is needed, pass the request on down the chain; otherwise just return an indication that the value is in the same register as the next frame. */ if (bufferp == NULL) { *optimizedp = 0; *lvalp = lval_register; *addrp = 0; *realnump = regnum; } else { frame_register_unwind (frame->next, regnum, optimizedp, lvalp, addrp, realnump, bufferp); } } static CORE_ADDR frame_saved_regs_pc_unwind (struct frame_info *frame, void **cache) { return FRAME_SAVED_PC (frame); } /* Function: get_saved_register Find register number REGNUM relative to FRAME and put its (raw, target format) contents in *RAW_BUFFER. Set *OPTIMIZED if the variable was optimized out (and thus can't be fetched). Note that this is never set to anything other than zero in this implementation. Set *LVAL to lval_memory, lval_register, or not_lval, depending on whether the value was fetched from memory, from a register, or in a strange and non-modifiable way (e.g. a frame pointer which was calculated rather than fetched). We will use not_lval for values fetched from generic dummy frames. Set *ADDRP to the address, either in memory or as a REGISTER_BYTE offset into the registers array. If the value is stored in a dummy frame, set *ADDRP to zero. To use this implementation, define a function called "get_saved_register" in your target code, which simply passes all of its arguments to this function. The argument RAW_BUFFER must point to aligned memory. */ void deprecated_generic_get_saved_register (char *raw_buffer, int *optimized, CORE_ADDR *addrp, struct frame_info *frame, int regnum, enum lval_type *lval) { if (!target_has_registers) error ("No registers."); /* Normal systems don't optimize out things with register numbers. */ if (optimized != NULL) *optimized = 0; if (addrp) /* default assumption: not found in memory */ *addrp = 0; /* Note: since the current frame's registers could only have been saved by frames INTERIOR TO the current frame, we skip examining the current frame itself: otherwise, we would be getting the previous frame's registers which were saved by the current frame. */ while (frame && ((frame = frame->next) != NULL)) { if (get_frame_type (frame) == DUMMY_FRAME) { if (lval) /* found it in a CALL_DUMMY frame */ *lval = not_lval; if (raw_buffer) /* FIXME: cagney/2002-06-26: This should be via the gdbarch_register_read() method so that it, on the fly, constructs either a raw or pseudo register from the raw register cache. */ regcache_raw_read (generic_find_dummy_frame (frame->pc, frame->frame), regnum, raw_buffer); return; } FRAME_INIT_SAVED_REGS (frame); if (frame->saved_regs != NULL && frame->saved_regs[regnum] != 0) { if (lval) /* found it saved on the stack */ *lval = lval_memory; if (regnum == SP_REGNUM) { if (raw_buffer) /* SP register treated specially */ store_address (raw_buffer, REGISTER_RAW_SIZE (regnum), frame->saved_regs[regnum]); } else { if (addrp) /* any other register */ *addrp = frame->saved_regs[regnum]; if (raw_buffer) read_memory (frame->saved_regs[regnum], raw_buffer, REGISTER_RAW_SIZE (regnum)); } return; } } /* If we get thru the loop to this point, it means the register was not saved in any frame. Return the actual live-register value. */ if (lval) /* found it in a live register */ *lval = lval_register; if (addrp) *addrp = REGISTER_BYTE (regnum); if (raw_buffer) deprecated_read_register_gen (regnum, raw_buffer); } /* Using the PC, select a mechanism for unwinding a frame returning the previous frame. The register unwind function should, on demand, initialize the ->context object. */ static void set_unwind_by_pc (CORE_ADDR pc, CORE_ADDR fp, frame_register_unwind_ftype **unwind_register, frame_pc_unwind_ftype **unwind_pc) { if (!DEPRECATED_USE_GENERIC_DUMMY_FRAMES) { /* Still need to set this to something. The ``info frame'' code calls this function to find out where the saved registers are. Hopefully this is robust enough to stop any core dumps and return vaguely correct values.. */ *unwind_register = frame_saved_regs_register_unwind; *unwind_pc = frame_saved_regs_pc_unwind; } else if (DEPRECATED_PC_IN_CALL_DUMMY_P () ? DEPRECATED_PC_IN_CALL_DUMMY (pc, 0, 0) : pc_in_dummy_frame (pc)) { *unwind_register = dummy_frame_register_unwind; *unwind_pc = dummy_frame_pc_unwind; } else { *unwind_register = frame_saved_regs_register_unwind; *unwind_pc = frame_saved_regs_pc_unwind; } } /* Create an arbitrary (i.e. address specified by user) or innermost frame. Always returns a non-NULL value. */ struct frame_info * create_new_frame (CORE_ADDR addr, CORE_ADDR pc) { struct frame_info *fi; enum frame_type type; fi = (struct frame_info *) obstack_alloc (&frame_cache_obstack, sizeof (struct frame_info)); /* Zero all fields by default. */ memset (fi, 0, sizeof (struct frame_info)); fi->frame = addr; fi->pc = pc; /* NOTE: cagney/2002-11-18: The code segments, found in create_new_frame and get_prev_frame(), that initializes the frames type is subtly different. The latter only updates ->type when it encounters a SIGTRAMP_FRAME or DUMMY_FRAME. This stops get_prev_frame() overriding the frame's type when the INIT code has previously set it. This is really somewhat bogus. The initialization, as seen in create_new_frame(), should occur before the INIT function has been called. */ if (DEPRECATED_USE_GENERIC_DUMMY_FRAMES && (DEPRECATED_PC_IN_CALL_DUMMY_P () ? DEPRECATED_PC_IN_CALL_DUMMY (pc, 0, 0) : pc_in_dummy_frame (pc))) /* NOTE: cagney/2002-11-11: Does this even occure? */ type = DUMMY_FRAME; else { char *name; find_pc_partial_function (pc, &name, NULL, NULL); if (PC_IN_SIGTRAMP (fi->pc, name)) type = SIGTRAMP_FRAME; else type = NORMAL_FRAME; } fi->type = type; if (INIT_EXTRA_FRAME_INFO_P ()) INIT_EXTRA_FRAME_INFO (0, fi); /* Select/initialize an unwind function. */ set_unwind_by_pc (fi->pc, fi->frame, &fi->register_unwind, &fi->pc_unwind); return fi; } /* Return the frame that FRAME calls (NULL if FRAME is the innermost frame). */ struct frame_info * get_next_frame (struct frame_info *frame) { return frame->next; } /* Flush the entire frame cache. */ void flush_cached_frames (void) { /* Since we can't really be sure what the first object allocated was */ obstack_free (&frame_cache_obstack, 0); obstack_init (&frame_cache_obstack); current_frame = NULL; /* Invalidate cache */ select_frame (NULL); annotate_frames_invalid (); } /* Flush the frame cache, and start a new one if necessary. */ void reinit_frame_cache (void) { flush_cached_frames (); /* FIXME: The inferior_ptid test is wrong if there is a corefile. */ if (PIDGET (inferior_ptid) != 0) { select_frame (get_current_frame ()); } } /* Return a structure containing various interesting information about the frame that called NEXT_FRAME. Returns NULL if there is no such frame. */ struct frame_info * get_prev_frame (struct frame_info *next_frame) { CORE_ADDR address = 0; struct frame_info *prev; int fromleaf; /* Return the inner-most frame, when the caller passes in NULL. */ /* NOTE: cagney/2002-11-09: Not sure how this would happen. The caller should have previously obtained a valid frame using get_selected_frame() and then called this code - only possibility I can think of is code behaving badly. */ if (next_frame == NULL) { /* NOTE: cagney/2002-11-09: There was a code segment here that would error out when CURRENT_FRAME was NULL. The comment that went with it made the claim ... ``This screws value_of_variable, which just wants a nice clean NULL return from block_innermost_frame if there are no frames. I don't think I've ever seen this message happen otherwise. And returning NULL here is a perfectly legitimate thing to do.'' Per the above, this code shouldn't even be called with a NULL NEXT_FRAME. */ return current_frame; } /* Only try to do the unwind once. */ if (next_frame->prev_p) return next_frame->prev; next_frame->prev_p = 1; /* On some machines it is possible to call a function without setting up a stack frame for it. On these machines, we define this macro to take two args; a frameinfo pointer identifying a frame and a variable to set or clear if it is or isn't leafless. */ /* Still don't want to worry about this except on the innermost frame. This macro will set FROMLEAF if NEXT_FRAME is a frameless function invocation. */ if (next_frame->next == NULL) /* FIXME: 2002-11-09: Frameless functions can occure anywhere in the frame chain, not just the inner most frame! The generic, per-architecture, frame code should handle this and the below should simply be removed. */ fromleaf = FRAMELESS_FUNCTION_INVOCATION (next_frame); else fromleaf = 0; if (fromleaf) /* A frameless inner-most frame. The `FP' (which isn't an architecture frame-pointer register!) of the caller is the same as the callee. */ /* FIXME: 2002-11-09: There isn't any reason to special case this edge condition. Instead the per-architecture code should hande it locally. */ address = get_frame_base (next_frame); else { /* Two macros defined in tm.h specify the machine-dependent actions to be performed here. First, get the frame's chain-pointer. If that is zero, the frame is the outermost frame or a leaf called by the outermost frame. This means that if start calls main without a frame, we'll return 0 (which is fine anyway). Nope; there's a problem. This also returns when the current routine is a leaf of main. This is unacceptable. We move this to after the ffi test; I'd rather have backtraces from start go curfluy than have an abort called from main not show main. */ address = FRAME_CHAIN (next_frame); /* FIXME: cagney/2002-06-08: There should be two tests here. The first would check for a valid frame chain based on a user selectable policy. The default being ``stop at main'' (as implemented by generic_func_frame_chain_valid()). Other policies would be available - stop at NULL, .... The second test, if provided by the target architecture, would check for more exotic cases - most target architectures wouldn't bother with this second case. */ if (!FRAME_CHAIN_VALID (address, next_frame)) return 0; } if (address == 0) return 0; /* Create an initially zero previous frame. */ prev = (struct frame_info *) obstack_alloc (&frame_cache_obstack, sizeof (struct frame_info)); memset (prev, 0, sizeof (struct frame_info)); /* Link it in. */ next_frame->prev = prev; prev->next = next_frame; prev->frame = address; prev->level = next_frame->level + 1; /* FIXME: cagney/2002-11-18: Should be setting the frame's type here, before anything else, and not last. Various INIT functions are full of work-arounds for the frames type not being set correctly from the word go. Ulgh! */ prev->type = NORMAL_FRAME; /* This change should not be needed, FIXME! We should determine whether any targets *need* INIT_FRAME_PC to happen after INIT_EXTRA_FRAME_INFO and come up with a simple way to express what goes on here. INIT_EXTRA_FRAME_INFO is called from two places: create_new_frame (where the PC is already set up) and here (where it isn't). INIT_FRAME_PC is only called from here, always after INIT_EXTRA_FRAME_INFO. The catch is the MIPS, where INIT_EXTRA_FRAME_INFO requires the PC value (which hasn't been set yet). Some other machines appear to require INIT_EXTRA_FRAME_INFO before they can do INIT_FRAME_PC. Phoo. We shouldn't need INIT_FRAME_PC_FIRST to add more complication to an already overcomplicated part of GDB. gnu@cygnus.com, 15Sep92. Assuming that some machines need INIT_FRAME_PC after INIT_EXTRA_FRAME_INFO, one possible scheme: SETUP_INNERMOST_FRAME(): Default version is just create_new_frame (read_fp ()), read_pc ()). Machines with extra frame info would do that (or the local equivalent) and then set the extra fields. SETUP_ARBITRARY_FRAME(argc, argv): Only change here is that create_new_frame would no longer init extra frame info; SETUP_ARBITRARY_FRAME would have to do that. INIT_PREV_FRAME(fromleaf, prev) Replace INIT_EXTRA_FRAME_INFO and INIT_FRAME_PC. This should also return a flag saying whether to keep the new frame, or whether to discard it, because on some machines (e.g. mips) it is really awkward to have FRAME_CHAIN_VALID called *before* INIT_EXTRA_FRAME_INFO (there is no good way to get information deduced in FRAME_CHAIN_VALID into the extra fields of the new frame). std_frame_pc(fromleaf, prev) This is the default setting for INIT_PREV_FRAME. It just does what the default INIT_FRAME_PC does. Some machines will call it from INIT_PREV_FRAME (either at the beginning, the end, or in the middle). Some machines won't use it. kingdon@cygnus.com, 13Apr93, 31Jan94, 14Dec94. */ /* NOTE: cagney/2002-11-09: Just ignore the above! There is no reason for things to be this complicated. The trick is to assume that there is always a frame. Instead of special casing the inner-most frame, create fake frame (containing the hardware registers) that is inner to the user-visible inner-most frame (...) and then unwind from that. That way architecture code can use use the standard frame_XX_unwind() functions and not differentiate between the inner most and any other case. Since there is always a frame to unwind from, there is always somewhere (NEXT_FRAME) to store all the info needed to construct a new (previous) frame without having to first create it. This means that the convolution below - needing to carefully order a frame's initialization - isn't needed. The irony here though, is that FRAME_CHAIN(), at least for a more up-to-date architecture, always calls FRAME_SAVED_PC(), and FRAME_SAVED_PC() computes the PC but without first needing the frame! Instead of the convolution below, we could have simply called FRAME_SAVED_PC() and been done with it! Note that FRAME_SAVED_PC() is being superseed by frame_pc_unwind() and that function does have somewhere to cache that PC value. */ INIT_FRAME_PC_FIRST (fromleaf, prev); if (INIT_EXTRA_FRAME_INFO_P ()) INIT_EXTRA_FRAME_INFO (fromleaf, prev); /* This entry is in the frame queue now, which is good since FRAME_SAVED_PC may use that queue to figure out its value (see tm-sparc.h). We want the pc saved in the inferior frame. */ INIT_FRAME_PC (fromleaf, prev); /* If ->frame and ->pc are unchanged, we are in the process of getting ourselves into an infinite backtrace. Some architectures check this in FRAME_CHAIN or thereabouts, but it seems like there is no reason this can't be an architecture-independent check. */ if (prev->frame == next_frame->frame && prev->pc == next_frame->pc) { next_frame->prev = NULL; obstack_free (&frame_cache_obstack, prev); return NULL; } /* Initialize the code used to unwind the frame PREV based on the PC (and probably other architectural information). The PC lets you check things like the debug info at that point (dwarf2cfi?) and use that to decide how the frame should be unwound. */ set_unwind_by_pc (prev->pc, prev->frame, &prev->register_unwind, &prev->pc_unwind); /* NOTE: cagney/2002-11-18: The code segments, found in create_new_frame and get_prev_frame(), that initializes the frames type is subtly different. The latter only updates ->type when it encounters a SIGTRAMP_FRAME or DUMMY_FRAME. This stops get_prev_frame() overriding the frame's type when the INIT code has previously set it. This is really somewhat bogus. The initialization, as seen in create_new_frame(), should occur before the INIT function has been called. */ if (DEPRECATED_USE_GENERIC_DUMMY_FRAMES && (DEPRECATED_PC_IN_CALL_DUMMY_P () ? DEPRECATED_PC_IN_CALL_DUMMY (prev->pc, 0, 0) : pc_in_dummy_frame (prev->pc))) prev->type = DUMMY_FRAME; else { /* FIXME: cagney/2002-11-10: This should be moved to before the INIT code above so that the INIT code knows what the frame's type is (in fact, for a [generic] dummy-frame, the type can be set and then the entire initialization can be skipped. Unforunatly, its the INIT code that sets the PC (Hmm, catch 22). */ char *name; find_pc_partial_function (prev->pc, &name, NULL, NULL); if (PC_IN_SIGTRAMP (prev->pc, name)) prev->type = SIGTRAMP_FRAME; /* FIXME: cagney/2002-11-11: Leave prev->type alone. Some architectures are forcing the frame's type in INIT so we don't want to override it here. Remember, NORMAL_FRAME == 0, so it all works (just :-/). Once this initialization is moved to the start of this function, all this nastness will go away. */ } return prev; } CORE_ADDR get_frame_pc (struct frame_info *frame) { return frame->pc; } static int pc_notcurrent (struct frame_info *frame) { /* If FRAME is not the innermost frame, that normally means that FRAME->pc points at the return instruction (which is *after* the call instruction), and we want to get the line containing the call (because the call is where the user thinks the program is). However, if the next frame is either a SIGTRAMP_FRAME or a DUMMY_FRAME, then the next frame will contain a saved interrupt PC and such a PC indicates the current (rather than next) instruction/line, consequently, for such cases, want to get the line containing fi->pc. */ struct frame_info *next = get_next_frame (frame); int notcurrent = (next != NULL && get_frame_type (next) == NORMAL_FRAME); return notcurrent; } void find_frame_sal (struct frame_info *frame, struct symtab_and_line *sal) { (*sal) = find_pc_line (frame->pc, pc_notcurrent (frame)); } /* Per "frame.h", return the ``address'' of the frame. Code should really be using get_frame_id(). */ CORE_ADDR get_frame_base (struct frame_info *fi) { return fi->frame; } /* Level of the selected frame: 0 for innermost, 1 for its caller, ... or -1 for a NULL frame. */ int frame_relative_level (struct frame_info *fi) { if (fi == NULL) return -1; else return fi->level; } enum frame_type get_frame_type (struct frame_info *frame) { /* Some targets still don't use [generic] dummy frames. Catch them here. */ if (!DEPRECATED_USE_GENERIC_DUMMY_FRAMES && deprecated_frame_in_dummy (frame)) return DUMMY_FRAME; return frame->type; } void deprecated_set_frame_type (struct frame_info *frame, enum frame_type type) { /* Arrrg! See comment in "frame.h". */ frame->type = type; } #ifdef FRAME_FIND_SAVED_REGS /* XXX - deprecated. This is a compatibility function for targets that do not yet implement FRAME_INIT_SAVED_REGS. */ /* Find the addresses in which registers are saved in FRAME. */ void get_frame_saved_regs (struct frame_info *frame, struct frame_saved_regs *saved_regs_addr) { if (frame->saved_regs == NULL) { frame->saved_regs = (CORE_ADDR *) frame_obstack_alloc (SIZEOF_FRAME_SAVED_REGS); } if (saved_regs_addr == NULL) { struct frame_saved_regs saved_regs; FRAME_FIND_SAVED_REGS (frame, saved_regs); memcpy (frame->saved_regs, &saved_regs, SIZEOF_FRAME_SAVED_REGS); } else { FRAME_FIND_SAVED_REGS (frame, *saved_regs_addr); memcpy (frame->saved_regs, saved_regs_addr, SIZEOF_FRAME_SAVED_REGS); } } #endif void _initialize_frame (void) { obstack_init (&frame_cache_obstack); }