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SubjectRe: [PATCH v2] perf jvmti: Remove redundant jitdump line table entries
On Wed, May 27, 2020 at 10:41 PM Nick Gasson <nick.gasson@arm.com> wrote:
>
> For each PC/BCI pair in the JVMTI compiler inlining record table, the
> jitdump plugin emits debug line table entries for every source line in
> the method preceding that BCI. Instead only emit one source line per
> PC/BCI pair. Reported by Ian Rogers. This reduces the .dump size for
> SPECjbb from ~230MB to ~40MB.
>
> Signed-off-by: Nick Gasson <nick.gasson@arm.com>
> ---
> Changes in v2:
> - Split the unrelated DWARF debug fix into a separate patch
> - Added a comment about the use of c->methods
>
> tools/perf/jvmti/libjvmti.c | 78 ++++++++++++++++---------------------
> 1 file changed, 33 insertions(+), 45 deletions(-)
>
> diff --git a/tools/perf/jvmti/libjvmti.c b/tools/perf/jvmti/libjvmti.c
> index c5d30834a64c..fcca275e5bf9 100644
> --- a/tools/perf/jvmti/libjvmti.c
> +++ b/tools/perf/jvmti/libjvmti.c
> @@ -32,38 +32,41 @@ static void print_error(jvmtiEnv *jvmti, const char *msg, jvmtiError ret)
>
> #ifdef HAVE_JVMTI_CMLR
> static jvmtiError
> -do_get_line_numbers(jvmtiEnv *jvmti, void *pc, jmethodID m, jint bci,
> - jvmti_line_info_t *tab, jint *nr)
> +do_get_line_number(jvmtiEnv *jvmti, void *pc, jmethodID m, jint bci,
> + jvmti_line_info_t *tab)
> {
> - jint i, lines = 0;
> - jint nr_lines = 0;
> + jint i, nr_lines = 0;
> jvmtiLineNumberEntry *loc_tab = NULL;
> jvmtiError ret;
> + jint src_line = -1;
>
> ret = (*jvmti)->GetLineNumberTable(jvmti, m, &nr_lines, &loc_tab);
> if (ret == JVMTI_ERROR_ABSENT_INFORMATION || ret == JVMTI_ERROR_NATIVE_METHOD) {
> /* No debug information for this method */
> - *nr = 0;
> - return JVMTI_ERROR_NONE;
> + return ret;
> } else if (ret != JVMTI_ERROR_NONE) {
> print_error(jvmti, "GetLineNumberTable", ret);
> return ret;
> }
>
> - for (i = 0; i < nr_lines; i++) {
> - if (loc_tab[i].start_location < bci) {
> - tab[lines].pc = (unsigned long)pc;
> - tab[lines].line_number = loc_tab[i].line_number;
> - tab[lines].discrim = 0; /* not yet used */
> - tab[lines].methodID = m;
> - lines++;
> - } else {
> - break;
> - }
> + for (i = 0; i < nr_lines && loc_tab[i].start_location <= bci; i++) {
> + src_line = i;
> + }
> +
> + if (src_line != -1) {
> + tab->pc = (unsigned long)pc;
> + tab->line_number = loc_tab[src_line].line_number;
> + tab->discrim = 0; /* not yet used */
> + tab->methodID = m;
> +
> + ret = JVMTI_ERROR_NONE;
> + } else {
> + ret = JVMTI_ERROR_ABSENT_INFORMATION;
> }
> +
> (*jvmti)->Deallocate(jvmti, (unsigned char *)loc_tab);
> - *nr = lines;
> - return JVMTI_ERROR_NONE;
> +
> + return ret;
> }
>
> static jvmtiError
> @@ -71,9 +74,8 @@ get_line_numbers(jvmtiEnv *jvmti, const void *compile_info, jvmti_line_info_t **
> {
> const jvmtiCompiledMethodLoadRecordHeader *hdr;
> jvmtiCompiledMethodLoadInlineRecord *rec;
> - jvmtiLineNumberEntry *lne = NULL;
> PCStackInfo *c;
> - jint nr, ret;
> + jint ret;
> int nr_total = 0;
> int i, lines_total = 0;
>
> @@ -86,24 +88,7 @@ get_line_numbers(jvmtiEnv *jvmti, const void *compile_info, jvmti_line_info_t **
> for (hdr = compile_info; hdr != NULL; hdr = hdr->next) {
> if (hdr->kind == JVMTI_CMLR_INLINE_INFO) {
> rec = (jvmtiCompiledMethodLoadInlineRecord *)hdr;
> - for (i = 0; i < rec->numpcs; i++) {
> - c = rec->pcinfo + i;
> - nr = 0;
> - /*
> - * unfortunately, need a tab to get the number of lines!
> - */
> - ret = (*jvmti)->GetLineNumberTable(jvmti, c->methods[0], &nr, &lne);
> - if (ret == JVMTI_ERROR_NONE) {
> - /* free what was allocated for nothing */
> - (*jvmti)->Deallocate(jvmti, (unsigned char *)lne);
> - nr_total += (int)nr;
> - } else if (ret == JVMTI_ERROR_ABSENT_INFORMATION ||
> - ret == JVMTI_ERROR_NATIVE_METHOD) {
> - /* No debug information for this method */
> - } else {
> - print_error(jvmti, "GetLineNumberTable", ret);
> - }
> - }
> + nr_total += rec->numpcs;
> }
> }
>
> @@ -122,14 +107,17 @@ get_line_numbers(jvmtiEnv *jvmti, const void *compile_info, jvmti_line_info_t **
> rec = (jvmtiCompiledMethodLoadInlineRecord *)hdr;
> for (i = 0; i < rec->numpcs; i++) {
> c = rec->pcinfo + i;
> - nr = 0;
> - ret = do_get_line_numbers(jvmti, c->pc,
> - c->methods[0],
> - c->bcis[0],
> - *tab + lines_total,
> - &nr);
> + /*
> + * c->methods is the stack of inlined method calls
> + * at c->pc. [0] is the leaf method. Caller frames
> + * are ignored at the moment.
> + */

Thanks!

Acked-by: Ian Rogers <irogers@google.com>

> + ret = do_get_line_number(jvmti, c->pc,
> + c->methods[0],
> + c->bcis[0],
> + *tab + lines_total);
> if (ret == JVMTI_ERROR_NONE)
> - lines_total += nr;
> + lines_total++;
> }
> }
> }
> --
> 2.26.2
>

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