[PATCH 25/48] perf annotate-data: Handle macro fusion on x86

From: Namhyung Kim
Date: Wed Oct 11 2023 - 23:54:30 EST


When a sample was come from a conditional branch without a memory
operand, it could be due to a macro fusion with a previous instruction.
So it needs to check the memory operand in the previous one.

This improves the stat like below:

Annotate data type stats:
total 294, ok 147 (50.0%), bad 147 (50.0%)
-----------------------------------------------------------
30 : no_sym
32 : no_mem_ops
71 : no_var
6 : no_typeinfo
8 : bad_offset

Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
---
tools/perf/util/annotate.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index 190489df0fb7..b0893d8f2ae3 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -3710,6 +3710,7 @@ struct annotated_data_type *hist_entry__get_data_type(struct hist_entry *he)
return NULL;
}

+retry:
istat = annotate_data_stat(&ann_insn_stat, dl->ins.name);
if (istat == NULL) {
ann_data_stat.no_insn++;
@@ -3726,7 +3727,7 @@ struct annotated_data_type *hist_entry__get_data_type(struct hist_entry *he)
if (!op_loc->mem_ref)
continue;

- /* Recalculate IP since it can be changed due to LOCK prefix */
+ /* Recalculate IP because of LOCK prefix or insn fusion */
ip = ms->sym->start + dl->al.offset;

mem_type = find_data_type(ms, ip, op_loc->reg, op_loc->offset);
@@ -3745,6 +3746,20 @@ struct annotated_data_type *hist_entry__get_data_type(struct hist_entry *he)
return mem_type;
}

+ /*
+ * Some instructions can be fused and the actual memory access came
+ * from the previous instruction.
+ */
+ if (dl->al.offset > 0) {
+ struct disasm_line *prev_dl;
+
+ prev_dl = list_prev_entry(dl, al.node);
+ if (ins__is_fused(arch, prev_dl->ins.name, dl->ins.name)) {
+ dl = prev_dl;
+ goto retry;
+ }
+ }
+
ann_data_stat.no_mem_ops++;
istat->bad++;
return NULL;
--
2.42.0.655.g421f12c284-goog