fix(modern): move args declaration at the beginning

[Andreagit97]

What type of PR is this?

/kind bug

Any specific area of the project related to this PR?

/area driver-modern-bpf

Does this PR require a change in the driver versions?

No

What this PR does / why we need it:

Extracting arguments in the middle of the program logic causes a side effect on how the compiler uses the registers. Moving the extraction at the beginning solves the issue

Which issue(s) this PR fixes:

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[FedeDP]

/approve

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Andreagit97, FedeDP

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Needs approval from an approver in each of these files:

• driver/OWNERS [Andreagit97,FedeDP]

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[poiana]

LGTM label has been added.

Git tree hash: 989dde40ddbf9824d103392479779feacf7c67a1

[FedeDP]

This PR fixes master failures on modern bpf against linux 5.8.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.44%. Comparing base (d1881b4) to head (5df4aec).
Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2220   +/-   ##
=======================================
  Coverage   75.44%   75.44%           
=======================================
  Files         265      265           
  Lines       34057    34057           
  Branches     5801     5801           
=======================================
+ Hits        25694    25695    +1     
+ Misses       8363     8362    -1     

Flag	Coverage Δ
libsinsp	75.44% <ø> (+<0.01%)	⬆️

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[github-actions]

Perf diff from master - unit tests

    10.95%     +0.95%  [.] sinsp::next
     8.00%     +0.66%  [.] sinsp_evt::get_type
     5.17%     +0.53%  [.] next_event_from_file
     4.13%     -0.43%  [.] sinsp_evt::load_params
     9.93%     +0.42%  [.] sinsp_parser::reset
     1.97%     +0.34%  [.] is_conversion_needed
     1.51%     -0.30%  [.] libsinsp::sinsp_suppress::process_event
     2.81%     -0.27%  [.] sinsp_parser::process_event
     0.80%     -0.25%  [.] sinsp_fdtable::find
     0.82%     -0.21%  [.] sinsp_evt::get_param

Heap diff from master - unit tests

peak heap memory consumption: 0B
peak RSS (including heaptrack overhead): 0B
total memory leaked: 0B

Heap diff from master - scap file

peak heap memory consumption: 0B
peak RSS (including heaptrack overhead): 0B
total memory leaked: 0B

Benchmarks diff from master

Comparing gbench_data.json to /root/actions-runner/_work/libs/libs/build/gbench_data.json
Benchmark                                                         Time             CPU      Time Old      Time New       CPU Old       CPU New
----------------------------------------------------------------------------------------------------------------------------------------------
BM_sinsp_split_mean                                            +0.0510         +0.0509           144           152           144           152
BM_sinsp_split_median                                          +0.0542         +0.0541           144           152           144           152
BM_sinsp_split_stddev                                          -0.6186         -0.6185             1             1             1             1
BM_sinsp_split_cv                                              -0.6371         -0.6370             0             0             0             0
BM_sinsp_concatenate_paths_relative_path_mean                  +0.0126         +0.0125            61            61            61            61
BM_sinsp_concatenate_paths_relative_path_median                +0.0148         +0.0147            61            62            61            62
BM_sinsp_concatenate_paths_relative_path_stddev                -0.6030         -0.6031             1             0             1             0
BM_sinsp_concatenate_paths_relative_path_cv                    -0.6079         -0.6080             0             0             0             0
BM_sinsp_concatenate_paths_empty_path_mean                     +0.0215         +0.0214            23            24            23            24
BM_sinsp_concatenate_paths_empty_path_median                   +0.0216         +0.0215            23            24            23            24
BM_sinsp_concatenate_paths_empty_path_stddev                   -0.2351         -0.2327             0             0             0             0
BM_sinsp_concatenate_paths_empty_path_cv                       -0.2512         -0.2488             0             0             0             0
BM_sinsp_concatenate_paths_absolute_path_mean                  -0.0003         -0.0004            65            65            65            65
BM_sinsp_concatenate_paths_absolute_path_median                +0.0004         +0.0004            64            65            64            65
BM_sinsp_concatenate_paths_absolute_path_stddev                -0.4171         -0.4167             0             0             0             0
BM_sinsp_concatenate_paths_absolute_path_cv                    -0.4169         -0.4164             0             0             0             0
BM_sinsp_split_container_image_mean                            +0.0221         +0.0220           391           399           391           399
BM_sinsp_split_container_image_median                          +0.0212         +0.0211           392           400           392           400
BM_sinsp_split_container_image_stddev                          -0.0038         -0.0038             3             3             3             3
BM_sinsp_split_container_image_cv                              -0.0253         -0.0252             0             0             0             0