[Bug c/100009] New: -march=native doesn't recognize tigerlake

[cdotts at planetiq dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100009

            Bug ID: 100009
           Summary: -march=native doesn't recognize tigerlake
           Product: gcc
           Version: 9.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: cdotts at planetiq dot com
  Target Milestone: ---

Copied from email chain: 
We're using GCC v9.3.0 on a newer laptop, as packaged by Ubuntu for
20.04 LTS.  Our build for host-native tools naturally enables
cpu-specific optimization with `-march=native`.  The gcc driver is
passing -march=tigerlake down to cc1 (or cc1plus).  The driver
program's auto-detection is correct in that this is tiger lake
hardware.  However, it is not supported in this release of GCC.

How exactly is the driver coming up with this code name?  I'd like to
keep the Makefile set up as-is for the whole team.  Can we override
the definition of `native` through an environment variable or
something?  Ice lake client optimizations and instruction selection
appear to be working for our usage.  We can modify the Makefile to be
sensitive to an environment variable, but I'm wondering if GCC itself
can also be overridden in this way.

Response from Jim Wilson: 
Looks like a bug in gcc-9.  tigerlake was added to
gcc/config/i386/driver-i386.c but not to the arch_names_table in i386.c.  I
would suggest filing a bug report.  I don't think there is a way to workaround
this.  It needs to be fixed in the gcc source tree.