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Message-ID: <CAP-5=fX-LASq92NCAd-8+41S9Bo_8xiH7iEGvKZqRbSdM-9zkw@mail.gmail.com>
Date: Fri, 2 Feb 2024 18:44:53 -0800
From: Ian Rogers <irogers@...gle.com>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>, 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 06/14] perf annotate-data: Maintain variable type info
On Fri, Feb 2, 2024 at 2:05 PM Namhyung Kim <namhyung@...nel.org> 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 | 155 ++++++++++++++++++++++++++++++++
> tools/perf/util/annotate-data.h | 29 ++++++
> tools/perf/util/dwarf-aux.c | 4 +
> 3 files changed, 188 insertions(+)
>
> diff --git a/tools/perf/util/annotate-data.c b/tools/perf/util/annotate-data.c
> index b8e60c42af8c..f8768c224bcc 100644
> --- a/tools/perf/util/annotate-data.c
> +++ b/tools/perf/util/annotate-data.c
> @@ -23,6 +23,57 @@
> #include "symbol.h"
> #include "symbol_conf.h"
>
> +/* Type information in a register, valid when ok is true */
> +struct type_state_reg {
> + Dwarf_Die type;
> + bool ok;
> + bool scratch;
> +};
> +
> +/* 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
Perhaps 32, presumably 16 won't work on Arm64.
Thanks,
Ian
> +
> +/*
> + * 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);
> +}
> +
> +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);
> + 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
> @@ -238,6 +289,110 @@ 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 update
> + * @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, 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);
> + } else if (var->reg == fbreg) {
> + findnew_stack_state(state, var->offset - fb_offset, &mem_die);
> + } else if (has_reg_type(state, var->reg)) {
> + struct type_state_reg *reg;
> +
> + reg = &state->regs[var->reg];
> + reg->type = mem_die;
> + reg->ok = true;
> + }
> + }
> +}
> +
> /* 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/annotate-data.h b/tools/perf/util/annotate-data.h
> index ad6493ea2c8e..7fbb9eb2e96f 100644
> --- a/tools/perf/util/annotate-data.h
> +++ b/tools/perf/util/annotate-data.h
> @@ -8,9 +8,12 @@
> #include <linux/types.h>
>
> struct annotated_op_loc;
> +struct arch;
> struct debuginfo;
> +struct die_var_type;
> struct evsel;
> struct map_symbol;
> +struct type_state;
>
> /**
> * struct annotated_member - Type of member field
> @@ -146,6 +149,16 @@ int annotated_data_type__update_samples(struct annotated_data_type *adt,
> /* Release all data type information in the tree */
> void annotated_data_type__tree_delete(struct rb_root *root);
>
> +/* Initialize type state table */
> +void init_type_state(struct type_state *state, struct arch *arch);
> +
> +/* Destroy type state table */
> +void exit_type_state(struct type_state *state);
> +
> +/* Update type state table using variables */
> +void update_var_state(struct type_state *state, struct data_loc_info *dloc,
> + u64 addr, struct die_var_type *var_types);
> +
> #else /* HAVE_DWARF_SUPPORT */
>
> static inline struct annotated_data_type *
> @@ -168,6 +181,22 @@ static inline void annotated_data_type__tree_delete(struct rb_root *root __maybe
> {
> }
>
> +static inline void init_type_state(struct type_state *state __maybe_unused,
> + struct arch *arch __maybe_unused)
> +{
> +}
> +
> +static inline void exit_type_state(struct type_state *state __maybe_unused)
> +{
> +}
> +
> +static inline void update_var_state(struct type_state *state __maybe_unused,
> + struct data_loc_info *dloc __maybe_unused,
> + u64 addr __maybe_unused,
> + struct die_var_type *var_types __maybe_unused)
> +{
> +}
> +
> #endif /* HAVE_DWARF_SUPPORT */
>
> #endif /* _PERF_ANNOTATE_DATA_H */
> diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
> index 39851ff1d5c4..f88a8fb4a350 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"
>
> @@ -1147,6 +1148,8 @@ 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;
> }
> @@ -1160,6 +1163,7 @@ 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;
> --
> 2.43.0.594.gd9cf4e227d-goog
>
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