Em Wed, May 13, 2020 at 06:47:38PM -0500, Gustavo A. R. Silva escreveu:
> Fix the following build failure generated with command
> $ make CC=clang HOSTCC=clang -C tools/ perf:
>
> util/intel-pt.c:1802:24: error: field 'br_stack' with variable sized type
> 'struct branch_stack' not at the end of a struct or class is a GNU extension
> [-Werror,-Wgnu-variable-sized-type-not-at-end]
> struct branch_stack br_stack;
> ^
> 1 error generated.
>
> Fix this by reordering the members of struct br.
Yeah, I noticed that as far back as with ubuntu 16.04's clang:
clang version 3.8.0-2ubuntu4 (tags/RELEASE_380/final)
util/intel-pt.c:1802:24: error: field 'br_stack' with variable sized type
'struct branch_stack' not at the end of a struct or class is a GNU
extension [-Werror,-Wgnu-variable-sized-type-not-at-end]
struct branch_stack br_stack;
^
1 error generated.
Will fold this with the bug introducing the problem to avoid bisection
problems.
> Clang version 11.0.0 was used.
>
> Fixes: f283f293a60d ("perf tools: Replace zero-length array with
> flexible-array")
> Reported-by: Ian Rogers <[email protected]>
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
> ---
> Here to fix what I break. :)
>
> tools/perf/util/intel-pt.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
> index f17b1e769ae4..b34179e3926f 100644
> --- a/tools/perf/util/intel-pt.c
> +++ b/tools/perf/util/intel-pt.c
> @@ -1799,8 +1799,8 @@ static int intel_pt_synth_pebs_sample(struct
> intel_pt_queue *ptq)
>
> if (sample_type & PERF_SAMPLE_BRANCH_STACK) {
> struct {
> - struct branch_stack br_stack;
> struct branch_entry entries[LBRS_MAX];
> + struct branch_stack br_stack;
> } br;
>
> if (items->mask[INTEL_PT_LBR_0_POS] ||
> --
> 2.26.2
>
--
- Arnaldo
