From 4a6ce9ad20257a9b8fc32994366a24170a3dfa3d Mon Sep 17 00:00:00 2001 From: Zecheng Li Date: Mon, 25 Aug 2025 19:54:05 +0000 Subject: [PATCH] perf dwarf-aux: Better variable collection for insn tracking Utilizes the previous is_breg_access_indirect function to determine if the register + offset stores the variable itself or the struct it points to, save the information in die_var_type.is_reg_var_addr. Since we are storing the real types in the stack state, we need to do a type dereference when is_reg_var_addr is set to false for stack/frame registers. For other gp registers, skip the variable when the register is a pointer to the type. If we want to accept these variables, we might also utilize is_reg_var_addr in a different way, we need to mark that register as a pointer to the type. Reviewed-by: Namhyung Kim Signed-off-by: Zecheng Li Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Ian Rogers Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kan Liang Cc: Mark Rutland Cc: Masami Hiramatsu Cc: Peter Zijlstra Cc: Xu Liu Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/annotate-data.c | 9 +++++++++ tools/perf/util/dwarf-aux.c | 11 ++++++++++- tools/perf/util/dwarf-aux.h | 2 ++ 3 files changed, 21 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/annotate-data.c b/tools/perf/util/annotate-data.c index 1ef2edbc71d9..258157cc43c2 100644 --- a/tools/perf/util/annotate-data.c +++ b/tools/perf/util/annotate-data.c @@ -868,6 +868,11 @@ static void update_var_state(struct type_state *state, struct data_loc_info *dlo int offset = var->offset; struct type_state_stack *stack; + /* If the reg location holds the pointer value, dereference the type */ + if (!var->is_reg_var_addr && is_pointer_type(&mem_die) && + __die_get_real_type(&mem_die, &mem_die) == NULL) + continue; + if (var->reg != DWARF_REG_FB) offset -= fb_offset; @@ -893,6 +898,10 @@ static void update_var_state(struct type_state *state, struct data_loc_info *dlo reg = &state->regs[var->reg]; + /* For gp registers, skip the address registers for now */ + if (var->is_reg_var_addr) + continue; + if (reg->ok && reg->kind == TSR_KIND_TYPE && !is_better_type(®->type, &mem_die)) continue; diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c index 449bc9ad7aff..6fd2db5d9381 100644 --- a/tools/perf/util/dwarf-aux.c +++ b/tools/perf/util/dwarf-aux.c @@ -1627,13 +1627,22 @@ static int __die_collect_vars_cb(Dwarf_Die *die_mem, void *arg) if (!check_allowed_ops(ops, nops)) return DIE_FIND_CB_SIBLING; - if (die_get_real_type(die_mem, &type_die) == NULL) + if (__die_get_real_type(die_mem, &type_die) == NULL) return DIE_FIND_CB_SIBLING; vt = malloc(sizeof(*vt)); if (vt == NULL) return DIE_FIND_CB_END; + /* Usually a register holds the value of a variable */ + vt->is_reg_var_addr = false; + + if (((ops->atom >= DW_OP_breg0 && ops->atom <= DW_OP_breg31) || + ops->atom == DW_OP_bregx || ops->atom == DW_OP_fbreg) && + !is_breg_access_indirect(ops, nops)) + /* The register contains an address of the variable. */ + vt->is_reg_var_addr = true; + vt->die_off = dwarf_dieoffset(&type_die); vt->addr = start; vt->reg = reg_from_dwarf_op(ops); diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h index 892c8c5c23fc..cd481ec9c5a1 100644 --- a/tools/perf/util/dwarf-aux.h +++ b/tools/perf/util/dwarf-aux.h @@ -148,6 +148,8 @@ struct die_var_type { u64 addr; int reg; int offset; + /* Whether the register holds a address to the type */ + bool is_reg_var_addr; }; /* Return type info of a member at offset */ -- 2.51.0