[Bug other/87444] New: 'gcc -marc=native' sets L2 cache size equal to L3 cache size on i7 and i5 CPU

[studio at anchev dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87444

            Bug ID: 87444
           Summary: 'gcc -marc=native' sets L2 cache size equal to L3
                    cache size on i7 and i5 CPU
           Product: gcc
           Version: 7.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: studio at anchev dot net
  Target Milestone: ---

STR:

gcc -### -march=native /usr/include/stdlib.h
lscpu | grep -i cache

OS: openSUSE Leap 15.0

EXPECTED:

gcc's output should show --param "l2-cache-size=<the same L2 cache which lscpu
shows>"

ACTUAL:

gcc outputs:
... --param "l2-cache-size=8192" ...

[~]: lscpu | grep -i cache
L1d cache:           32K
L1i cache:           32K
L2 cache:            256K
L3 cache:            8192K

The architecture is properly detected (ivybridge) but it seems l2-cache-size
equals the L3 cache, which is incorrect. The CPU model is "Intel(R) Core(TM)
i7-3770 CPU @ 3.40GHz"

A fellow openSUSE Leap 15.0 user shared that the same happens on "Intel(R)
Core(TM) i5-3210M CPU @ 2.50GHz" but not on AMD.

My own test on other machines shows that on "Intel(R) Xeon(TM) CPU 2.80GHz"
(nocona) and on "Intel(R) Celeron(R) M processor 1.50GHz" (pentium-m)
l2-cache-size is detected correctly. The nocona is running openSUSE Leap 15.0
and the pentium-m is running openSUSE Tumbleweed (32 bit).