From 82a38509d8f546be7150c47ad756dd096c0eb37c Mon Sep 17 00:00:00 2001 From: Peter Schauer Date: Sat, 2 Dec 1995 11:08:20 +0000 Subject: [PATCH] * 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. --- gdb/ChangeLog | 6 ++++++ gdb/alpha-tdep.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 59 insertions(+), 1 deletion(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 23d6a7b67a3..d7f1b98ac60 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -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 * ppcbug-rom.c (ppcbug_cmds): Turn on MO_GETMEM_READ_SINGLE diff --git a/gdb/alpha-tdep.c b/gdb/alpha-tdep.c index 622ee44de4c..7fbf6422e70 100644 --- a/gdb/alpha-tdep.c +++ b/gdb/alpha-tdep.c @@ -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; } -- 2.30.2