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Message-ID: <ZfmcN4YuvQpVgJQN@x1>
Date: Tue, 19 Mar 2024 11:07:51 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Ian Rogers <irogers@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
linux-perf-users@...r.kernel.org,
Linus Torvalds <torvalds@...ux-foundation.org>,
Stephane Eranian <eranian@...gle.com>,
Masami Hiramatsu <mhiramat@...nel.org>,
linux-toolchains@...r.kernel.org, linux-trace-devel@...r.kernel.org
Subject: Re: [PATCH 09/23] perf annotate-data: Maintain variable type info
On Mon, Mar 18, 2024 at 10:51:01PM -0700, Namhyung Kim wrote:
> As it collected basic block and variable information in each scope, it
> now can build a state table to find matching variable at the location.
>
> The struct type_state is to keep the type info saved in each register
> and stack slot. The update_var_state() updates the table when it finds
> variables in the current address. It expects die_collect_vars() filled
> a list of variables with type info and starting address.
>
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
> tools/perf/util/annotate-data.c | 173 ++++++++++++++++++++++++++++++++
> tools/perf/util/dwarf-aux.c | 4 +
> 2 files changed, 177 insertions(+)
>
> diff --git a/tools/perf/util/annotate-data.c b/tools/perf/util/annotate-data.c
> index f482ccfdaa91..8eaa06f1cee5 100644
> --- a/tools/perf/util/annotate-data.c
> +++ b/tools/perf/util/annotate-data.c
> @@ -46,6 +46,62 @@ static void pr_debug_type_name(Dwarf_Die *die)
> free(str);
> }
>
> +/* Type information in a register, valid when ok is true */
> +struct type_state_reg {
> + Dwarf_Die type;
> + bool ok;
> +};
> +
> +/* Type information in a stack location, dynamically allocated */
> +struct type_state_stack {
> + struct list_head list;
> + Dwarf_Die type;
> + int offset;
> + int size;
> + bool compound;
> +};
> +
> +/* FIXME: This should be arch-dependent */
> +#define TYPE_STATE_MAX_REGS 16
> +
> +/*
> + * State table to maintain type info in each register and stack location.
> + * It'll be updated when new variable is allocated or type info is moved
> + * to a new location (register or stack). As it'd be used with the
> + * shortest path of basic blocks, it only maintains a single table.
> + */
> +struct type_state {
> + struct type_state_reg regs[TYPE_STATE_MAX_REGS];
> + struct list_head stack_vars;
> +};
> +
> +static bool has_reg_type(struct type_state *state, int reg)
> +{
> + return (unsigned)reg < ARRAY_SIZE(state->regs);
> +}
> +
> +/* These declarations will be remove once they are changed to static */
> +void init_type_state(struct type_state *state, struct arch *arch __maybe_unused);
> +void exit_type_state(struct type_state *state);
> +void update_var_state(struct type_state *state, struct data_loc_info *dloc,
> + u64 addr, u64 insn_offset, struct die_var_type *var_types);
> +
> +void init_type_state(struct type_state *state, struct arch *arch __maybe_unused)
> +{
> + memset(state, 0, sizeof(*state));
> + INIT_LIST_HEAD(&state->stack_vars);
> +}
> +
> +void exit_type_state(struct type_state *state)
> +{
> + struct type_state_stack *stack, *tmp;
> +
> + list_for_each_entry_safe(stack, tmp, &state->stack_vars, list) {
> + list_del(&stack->list);
list_del_init()?
> + free(stack);
> + }
> +}
> +
> /*
> * Compare type name and size to maintain them in a tree.
> * I'm not sure if DWARF would have information of a single type in many
> @@ -262,6 +318,123 @@ static int check_variable(Dwarf_Die *var_die, Dwarf_Die *type_die, int offset,
> return 0;
> }
>
> +static struct type_state_stack *find_stack_state(struct type_state *state,
> + int offset)
> +{
> + struct type_state_stack *stack;
> +
> + list_for_each_entry(stack, &state->stack_vars, list) {
> + if (offset == stack->offset)
> + return stack;
> +
> + if (stack->compound && stack->offset < offset &&
> + offset < stack->offset + stack->size)
> + return stack;
> + }
> + return NULL;
> +}
> +
> +static void set_stack_state(struct type_state_stack *stack, int offset,
> + Dwarf_Die *type_die)
> +{
> + int tag;
> + Dwarf_Word size;
> +
> + if (dwarf_aggregate_size(type_die, &size) < 0)
> + size = 0;
> +
> + tag = dwarf_tag(type_die);
> +
> + stack->type = *type_die;
> + stack->size = size;
> + stack->offset = offset;
> +
> + switch (tag) {
> + case DW_TAG_structure_type:
> + case DW_TAG_union_type:
> + stack->compound = true;
> + break;
> + default:
> + stack->compound = false;
> + break;
> + }
> +}
> +
> +static struct type_state_stack *findnew_stack_state(struct type_state *state,
> + int offset, Dwarf_Die *type_die)
> +{
> + struct type_state_stack *stack = find_stack_state(state, offset);
> +
> + if (stack) {
> + set_stack_state(stack, offset, type_die);
> + return stack;
> + }
> +
> + stack = malloc(sizeof(*stack));
> + if (stack) {
> + set_stack_state(stack, offset, type_die);
> + list_add(&stack->list, &state->stack_vars);
> + }
> + return stack;
> +}
> +
> +/**
> + * update_var_state - Update type state using given variables
> + * @state: type state table
> + * @dloc: data location info
> + * @addr: instruction address to match with variable
> + * @insn_offset: instruction offset (for debug)
> + * @var_types: list of variables with type info
> + *
> + * This function fills the @state table using @var_types info. Each variable
> + * is used only at the given location and updates an entry in the table.
> + */
> +void update_var_state(struct type_state *state, struct data_loc_info *dloc,
> + u64 addr, u64 insn_offset, struct die_var_type *var_types)
> +{
> + Dwarf_Die mem_die;
> + struct die_var_type *var;
> + int fbreg = dloc->fbreg;
> + int fb_offset = 0;
> +
> + if (dloc->fb_cfa) {
> + if (die_get_cfa(dloc->di->dbg, addr, &fbreg, &fb_offset) < 0)
> + fbreg = -1;
> + }
> +
> + for (var = var_types; var != NULL; var = var->next) {
> + if (var->addr != addr)
> + continue;
> + /* Get the type DIE using the offset */
> + if (!dwarf_offdie(dloc->di->dbg, var->die_off, &mem_die))
> + continue;
> +
> + if (var->reg == DWARF_REG_FB) {
> + findnew_stack_state(state, var->offset, &mem_die);
> +
> + pr_debug_dtp("var [%"PRIx64"] -%#x(stack) type=",
> + insn_offset, -var->offset);
> + pr_debug_type_name(&mem_die);
> + } else if (var->reg == fbreg) {
> + findnew_stack_state(state, var->offset - fb_offset, &mem_die);
> +
> + pr_debug_dtp("var [%"PRIx64"] -%#x(stack) type=",
> + insn_offset, -var->offset + fb_offset);
> + pr_debug_type_name(&mem_die);
> + } else if (has_reg_type(state, var->reg) && var->offset == 0) {
> + struct type_state_reg *reg;
> +
> + reg = &state->regs[var->reg];
> + reg->type = mem_die;
> + reg->ok = true;
> +
> + pr_debug_dtp("var [%"PRIx64"] reg%d type=",
> + insn_offset, var->reg);
> + pr_debug_type_name(&mem_die);
> + }
> + }
> +}
> +
> /* The result will be saved in @type_die */
> static int find_data_type_die(struct data_loc_info *dloc, Dwarf_Die *type_die)
> {
> diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
> index 9080119a258c..41dbbb25b256 100644
> --- a/tools/perf/util/dwarf-aux.c
> +++ b/tools/perf/util/dwarf-aux.c
> @@ -9,6 +9,7 @@
> #include <stdlib.h>
> #include "debug.h"
> #include "dwarf-aux.h"
> +#include "dwarf-regs.h"
> #include "strbuf.h"
> #include "string2.h"
>
> @@ -1190,6 +1191,8 @@ static int reg_from_dwarf_op(Dwarf_Op *op)
> case DW_OP_regx:
> case DW_OP_bregx:
> return op->number;
> + case DW_OP_fbreg:
> + return DWARF_REG_FB;
> default:
> break;
> }
> @@ -1203,6 +1206,7 @@ static int offset_from_dwarf_op(Dwarf_Op *op)
> case DW_OP_regx:
> return 0;
> case DW_OP_breg0 ... DW_OP_breg31:
> + case DW_OP_fbreg:
> return op->number;
> case DW_OP_bregx:
> return op->number2;
> --
> 2.44.0.291.gc1ea87d7ee-goog
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