This is the mail archive of the gdb-patches@sourceware.org mailing list for the GDB project.
Index Nav: | [Date Index] [Subject Index] [Author Index] [Thread Index] | |
---|---|---|
Message Nav: | [Date Prev] [Date Next] | [Thread Prev] [Thread Next] |
Other format: | [Raw text] |
On Thursday 01 December 2005 17:07, Jim Blandy wrote: > Paul wanted to fast-track this patch, in hopes it could get into the > 6.4 release. Joel, what are your thoughts? > I guess this is now moot. Oh well. > I think the best alternative to deprecated_read_memory_nobpt would be > to actually call current_frame (this will be cheap, since we just > called it in watchpoint_check, before calling > gdbarch_in_function_epilogue_p) and then call > safe_frame_unwind_memory. > I revised the patch using your alternative (see below). > Whatever we do immediately, the underlying cause here is that > unwinding isn't working at every instruction. If it were, then the > call to frame_find_by_id would find the frame containing the watched > variable, and watchpoint_check would correctly conclude that the > variable was still in scope. > > Paul, does your test program have Dwarf CFI for the functions in question? > > I have attached a couple of dumps (and a typescript show how they where made), the executable, and the source. And here is the revised patch: 2005-12-02 Paul Gilliam <pgilliam@us.ibm.com> * rs6000-tdep.c: Add new subroutine, 'rs6000_in_function_epilogue_p()' and put it into the architecture vector. Index: rs6000-tdep.c =================================================================== RCS file: /cvs/src/src/gdb/rs6000-tdep.c,v retrieving revision 1.248 diff -a -u -p -r1.248 rs6000-tdep.c --- rs6000-tdep.c 1 Nov 2005 19:32:36 -0000 1.248 +++ rs6000-tdep.c 2 Dec 2005 18:43:19 -0000 @@ -502,6 +502,69 @@ rs6000_skip_prologue (CORE_ADDR pc) return pc; } +static int +insn_changes_sp(unsigned long insn) +{ + int opcode = (insn>>26) & 0x03f; + int sd = (insn>>21) & 0x01f; + int a = (insn>>16) & 0x01f; + int b = (insn>>11) & 0x01f; + int subcode = (insn>> 1) & 0x3ff; + int rc = insn & 0x001; + + if (opcode == 31 && subcode == 444 && a == 1) + return 1; /* mr R1,Rn */ + if (opcode == 14 && sd == 1) + return 1; /* addi R1,Rn,simm */ + if (opcode == 58 && sd == 1) + return 1; /* ld R1,ds(Rn) */ + + return 0; +} + +/* Return true if we are in the functin's epilogue, i.e. after the + instruction that destroyed the function's stack frame. */ +static int +rs6000_in_function_epilogue_p (struct gdbarch *gdbarch, CORE_ADDR pc) +{ + bfd_byte insn_buf[PPC_INSN_SIZE]; + CORE_ADDR scan_pc, func_addr, func_end; + unsigned long insn; + struct frame_info *fr; + + /* Find the search limits. */ + if (!find_pc_partial_function (pc, NULL, &func_addr, &func_end)) + return 0; + + /* Get the current frame. This may be cheap, since we might have just called + it in watchpoint_check, before calling gdbarch_in_function_epilogue_p. */ + + fr = get_current_frame (); + + /* Scan forward untill next 'blr'. */ + for (scan_pc = pc; scan_pc < func_end; scan_pc += PPC_INSN_SIZE) + { + if (!safe_frame_unwind_memory (fr, scan_pc, insn_buf, PPC_INSN_SIZE)) + return 0; + insn = extract_signed_integer (insn_buf, PPC_INSN_SIZE); + if (insn == 0x4e800020) break; + if (insn_changes_sp(insn)) + return 0; + } + + /* Scan backward untill adjustment to stack pointer (R1). */ + for (scan_pc=pc-PPC_INSN_SIZE; scan_pc>=func_addr; scan_pc-=PPC_INSN_SIZE) + { + if (!safe_frame_unwind_memory (fr, scan_pc, insn_buf, PPC_INSN_SIZE)) + return 0; + insn = extract_signed_integer (insn_buf, PPC_INSN_SIZE); + if (insn_changes_sp(insn)) + return 1; + } + + return 0; +} + /* Fill in fi->saved_regs */ @@ -3342,6 +3405,8 @@ rs6000_gdbarch_init (struct gdbarch_info set_gdbarch_deprecated_extract_struct_value_address (gdbarch, rs6000_extract_struct_value_address); set_gdbarch_skip_prologue (gdbarch, rs6000_skip_prologue); + set_gdbarch_in_function_epilogue_p (gdbarch, rs6000_in_function_epilogue_p); + set_gdbarch_inner_than (gdbarch, core_addr_lessthan); set_gdbarch_breakpoint_from_pc (gdbarch, rs6000_breakpoint_from_pc);
Attachment:
dump.typescript
Description: Text document
Attachment:
testwatch.readelf
Description: Text document
Attachment:
testwatch
Description: application/executable
int checkmeout = 0; char *lookatme = "I have not changed"; void subr2(int * addr) { *addr = 9; *addr = 1; } void subr1() { int watchthis = 9; subr2(&watchthis); checkmeout = 2; lookatme = "change is good"; watchthis = 2; } int main() { int ret_val = 0; subr1(); }
Attachment:
testwatch.objdmp
Description: Text document
Index Nav: | [Date Index] [Subject Index] [Author Index] [Thread Index] | |
---|---|---|
Message Nav: | [Date Prev] [Date Next] | [Thread Prev] [Thread Next] |