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* alpha-tdep.c (heuristic_proc_desc): Add heuristic to 

determine the return address register, needed for OSF/1-3.2C.
	* config/alpha/tm-alpha.h (T7_REGNUM, T9_REGNUM):  Define.
This commit is contained in:
Peter Schauer 1995-12-02 11:08:20 +00:00
parent 6ceb561287
commit 82a38509d8
2 changed files with 59 additions and 1 deletions
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6
gdb/ChangeLog
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@ -1,3 +1,9 @@
Sat Dec 2 03:02:21 1995 Peter Schauer (pes@regent.e-technik.tu-muenchen.de)
* alpha-tdep.c (heuristic_proc_desc): Add heuristic to
determine the return address register, needed for OSF/1-3.2C.
* config/alpha/tm-alpha.h (T7_REGNUM, T9_REGNUM): Define.
Fri Dec 1 07:23:57 1995 Michael Meissner <meissner@tiktok.cygnus.com>
* ppcbug-rom.c (ppcbug_cmds): Turn on MO_GETMEM_READ_SINGLE

54
gdb/alpha-tdep.c
View File

@ -359,6 +359,7 @@ heuristic_proc_desc(start_pc, limit_pc, next_frame)
int frame_size;
int has_frame_reg = 0;
unsigned long reg_mask = 0;
int pcreg = -1;
if (start_pc == 0)
return NULL;
@ -388,17 +389,68 @@ heuristic_proc_desc(start_pc, limit_pc, next_frame)
int reg = (word & 0x03e00000) >> 21;
reg_mask |= 1 << reg;
temp_saved_regs.regs[reg] = sp + (short)word;
/* Starting with OSF/1-3.2C, the system libraries are shipped
without local symbols, but they still contain procedure
descriptors without a symbol reference. GDB is currently
unable to find these procedure descriptors and uses
heuristic_proc_desc instead.
As some low level compiler support routines (__div*, __add*)
use a non-standard return address register, we have to
add some heuristics to determine the return address register,
or stepping over these routines will fail.
Usually the return address register is the first register
saved on the stack, but assembler optimization might
rearrange the register saves.
So we recognize only a few registers (t7, t9, ra) within
the procedure prologue as valid return address registers.
FIXME: Rewriting GDB to access the procedure descriptors,
e.g. via the minimal symbol table, might obviate this hack. */
if (pcreg == -1
&& cur_pc < (start_pc + 20)
&& (reg == T7_REGNUM || reg == T9_REGNUM || reg == RA_REGNUM))
pcreg = reg;
}
else if (word == 0x47de040f) /* bis sp,sp fp */
has_frame_reg = 1;
}
if (pcreg == -1)
{
/* If we haven't found a valid return address register yet,
keep searching in the procedure prologue. */
while (cur_pc < (limit_pc + 20) && cur_pc < (start_pc + 20))
{
char buf[4];
unsigned long word;
int status;
status = read_memory_nobpt (cur_pc, buf, 4);
if (status)
memory_error (status, cur_pc);
cur_pc += 4;
word = extract_unsigned_integer (buf, 4);
if ((word & 0xfc1f0000) == 0xb41e0000 /* stq reg,n($sp) */
&& (word & 0xffff0000) != 0xb7fe0000) /* reg != $zero */
{
int reg = (word & 0x03e00000) >> 21;
if (reg == T7_REGNUM || reg == T9_REGNUM || reg == RA_REGNUM)
{
pcreg = reg;
break;
}
}
}
}
if (has_frame_reg)
PROC_FRAME_REG(&temp_proc_desc) = GCC_FP_REGNUM;
else
PROC_FRAME_REG(&temp_proc_desc) = SP_REGNUM;
PROC_FRAME_OFFSET(&temp_proc_desc) = frame_size;
PROC_REG_MASK(&temp_proc_desc) = reg_mask;
PROC_PC_REG(&temp_proc_desc) = RA_REGNUM;
PROC_PC_REG(&temp_proc_desc) = (pcreg == -1) ? RA_REGNUM : pcreg;
PROC_LOCALOFF(&temp_proc_desc) = 0; /* XXX - bogus */
return &temp_proc_desc;
}