RFR: JDK-8200738 Use --hash-style=gnu for gcc

[David Holmes]

Hi Magnus,

On 13/06/2020 1:42 am, Magnus Ihse Bursie wrote:
> When support for gnu hash tables were added to the gcc toolchains, the 
> OpenJDK build system added a hack to change --hash-style=gnu to 
> --hash-style=both unconditionally, citing compatibility concerns.

Exactly how are these "hash styles" used? What difference does it make 
what style is used? Who raised the compatibility concerns?

Thanks,
David

> --hash-style=gnu has a very slight performance advantage over 
> --hash-style=both (very small static footprint reductions, tiny startup 
> cost differences). Both --hash-style=gnu and --hash-style=both have a 
> small to potentially large performance advantage over --hash-style=sysv
> 
> We should only use --hash-style=gnu. It's been the default in Ubuntu's 
> build of gcc since gcc 4.4[1], and likely similar in other distros.
> 
> I also removed LIBJSIG_NOEXECSTACK_LDFLAGS which is no longer used.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8200738
> WebRev: 
> http://cr.openjdk.java.net/~ihse/JDK-8200738-use-hash-style-gnu/webrev.01
> 
> /Magnus
> 
> [1] https://launchpad.net/ubuntu/maverick/+source/gcc-4.4/+changelog
>