gcc-4.0.x does not have __sync_synchronize() to be used for XFENCE

[mpsuzuki]

wc_port.h expects __sync_synchronize() in gcc-4.x, but it was introduced since gcc-4.1.0.

Please find the end of gcc/builtins.def in gcc-4.0 branch and gcc-4.1.0 (sorry, the changeset between gcc-4.0.4 and gcc-4.1.0 is too huge for github.com's comparison feature to display well).

gcc-4.0.x gcc/builtins.def

gcc-4.1.0 gcc/builtins.def

It would be safer to deal gcc-4.0 as gcc-3.x or older one.

Description

To build wolfSSL by ancient gcc on ancient platform, the C preprocessor-based function availability classification is improved.

Testing

Building wolfSSL with gcc-4.0.0 (on FreeBSD 5.5) finishes. Without this modification, the built libwolfssl.so would have an unresolvable reference to __sync_synchronize(), and it makes the linking of wolfcrypt/benchmark/benchmark failed as

src/.libs/libwolfssl.so: undefined reference to `__sync_synchronize'

Checklist

• [ ] added tests
• [ ] updated/added doxygen
• [ ] updated appropriate READMEs
• [ ] Updated manual and documentation

[wolfSSL-Bot]

Can one of the admins verify this patch?

[dgarske]

Okay to test. Contributor agreement on file.

[mpsuzuki]

Oh, what? During the check, a building test on latest macOS is reported as failed. I would try to reproduce the error in my environment...

[douzzer]

retest this please.

[douzzer]

retest this please

[dgarske]

Retest this please. History lost for failed PRB test.

[dgarske]

@mpsuzuki Can you please rebase to latest master? Getting a failure on [PRB-fips-repo-and-harness-test-v3-part2] but I cannot get the history. I think the PR change is okay.

[douzzer]

fixed by #8195 -- thank you @mpsuzuki for prompting the fix!

[mpsuzuki]

I apologize that I failed to rebase my patch timely, anyway, thank you for caring about the ancient gcc!