Warning about debug mode's affect on performance

[Scott Baden]

When building UPC++ using default settings, the library is built with debug enabled. This has an affect on performance. The following banner prints out near the start of the build.

However, most users my not see the banner, as it will whizz by during the build. I suggest you print it out again at the end of the build

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WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING

Configuring the system for global, forced debugging mode.
This usually has a SERIOUS impact on performance, so you should NOT
trust any performance numbers obtained from programs built
using this GASNet installation!!!

WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING

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[Dan Bonachea]

Hi Scott -

The normal UPC++ installation process actually configures and builds multiple versions of the GASNet and UPC++ libraries, along three different axes:

(single threaded vs thread-safe) x (network backend, eg smp, ibv, aries) x (debug vs production)

The message you are seeing is actually generated from the GASNet configure step for the debug portion of the library, and only applies to the libraries built along that dimension in the 3-d configure space.

We don't output any such warning at the end because the installer creates both debug and production libraries. The one you get is selected at UPC++ application compile time via upcxx -codemode or envvar UPCXX_CODEMODE, which defaults to a "smart" selection based on looking for -g or -O in the compile arguments.

Make sense?

[Dan Bonachea]

We've decided to suppress the misleading warning starting next release

[Dan Bonachea]

issue #420: Suppress harmless GASNet debug-mode configure warning

Resolves issue #420

→ <<cset 99c7dc9d6e23>>

[Scott Baden]

Sounds good