diff options
Diffstat (limited to 'gdb/nios2-tdep.c')
| -rw-r--r-- | gdb/nios2-tdep.c | 59 |
1 files changed, 42 insertions, 17 deletions
diff --git a/gdb/nios2-tdep.c b/gdb/nios2-tdep.c index aa26af9..2758012 100644 --- a/gdb/nios2-tdep.c +++ b/gdb/nios2-tdep.c @@ -589,26 +589,42 @@ nios2_in_epilogue_p (struct gdbarch *gdbarch, CORE_ADDR start_pc) { unsigned long mach = gdbarch_bfd_arch_info (gdbarch)->mach; + /* Maximum number of possibly-epilogue instructions to check. + Note that this number should not be too large, else we can + potentially end up iterating through unmapped memory. */ + int ninsns, max_insns = 5; unsigned int insn; const struct nios2_opcode *op = NULL; unsigned int uimm; int imm; int ra, rb, rc; enum branch_condition cond; + CORE_ADDR pc; /* There has to be a previous instruction in the function. */ - if (current_pc > start_pc) - { - int ok = 0; + if (current_pc <= start_pc) + return 0; - /* Check whether the previous instruction was a stack adjustment. - Possible instructions here include: + /* Find the previous instruction before current_pc. + For the moment we will assume that all instructions are the + same size here. */ + pc = current_pc - NIOS2_OPCODE_SIZE; + + /* Beginning with the previous instruction we just located, check whether + we are in a sequence of at least one stack adjustment instruction. + Possible instructions here include: ADDI sp, sp, n ADD sp, sp, rn LDW sp, n(sp) */ - op = nios2_fetch_insn (gdbarch, current_pc - NIOS2_OPCODE_SIZE, &insn); + for (ninsns = 0; ninsns < max_insns; ninsns++) + { + int ok = 0; + + /* Fetch the insn at pc. */ + op = nios2_fetch_insn (gdbarch, pc, &insn); if (op == NULL) return 0; + pc += op->size; /* Was it a stack adjustment? */ if (nios2_match_addi (insn, op, mach, &ra, &rb, &imm)) @@ -618,18 +634,27 @@ nios2_in_epilogue_p (struct gdbarch *gdbarch, else if (nios2_match_ldw (insn, op, mach, &ra, &rb, &imm)) ok = (rb == NIOS2_SP_REGNUM); if (!ok) - return 0; - - /* Then check if it's followed by a return or a tail call. */ - op = nios2_fetch_insn (gdbarch, current_pc, &insn); - if (op == NULL) - return 0; - if (nios2_match_jmpr (insn, op, mach, &ra) - || nios2_match_jmpi (insn, op, mach, &uimm) - || (nios2_match_branch (insn, op, mach, &ra, &rb, &imm, &cond) - && cond == branch_none)) - return 1; + break; } + + /* No stack adjustments found. */ + if (ninsns == 0) + return 0; + + /* We found more stack adjustments than we expect GCC to be generating. + Since it looks like a stack unwind might be in progress tell GDB to + treat it as such. */ + if (ninsns == max_insns) + return 1; + + /* The next instruction following the stack adjustments must be a + return, jump, or unconditional branch. */ + if (nios2_match_jmpr (insn, op, mach, &ra) + || nios2_match_jmpi (insn, op, mach, &uimm) + || (nios2_match_branch (insn, op, mach, &ra, &rb, &imm, &cond) + && cond == branch_none)) + return 1; + return 0; } |