RFR: JDK-8136695 Automatic build comparison with COMPARE_BUILD

[Erik Joelsson]

Nice work!

I wonder what happens if you invoke this target from the build output 
directory? I can imagine it not working too well, but would like a 
graceful exit in that case.

/Erik

On 2015-09-17 06:41, Magnus Ihse Bursie wrote:
> A common scenario in when working in the build system is to want to 
> check if a particular change results in a change in the build output 
> or not, or a more detailed analysis of such changes.
>
> The compare.sh tool will provide such an analysis, but only if you 
> have a pre-built baseline to compare with.
>
> To facilitate testing changes, especially on distributed job servers, 
> we should add a COMPARE_BUILD make control variable. If this variable 
> is present, the build will run twice, the second time with the code 
> that should be tested (particular make targets, configure arguments, 
> or with a patch file applied), and then automatically run the compare 
> script afterwards against the baseline.
>
> The suggested format allows for a very fine-grained control, by 
> further parsing the value of COMPARE_BUILD into separate parts. The 
> syntax looks like this:
> COMPARE_BUILD=CONF=<configure options>:PATCH=<patch file>:MAKE=<make 
> targets>:COMP_OPTS=<compare script options>|<default>
>
> If neither CONF or PATCH is given, assume <default> means CONF if it 
> begins with "--", otherwise assume it means PATCH. Either CONF or 
> PATCH must be given, directly specified or by using the default 
> syntax. The rest of the key/value pairs are optional, and they may 
> come in any order.
>
> MAKE and COMP_OPTS can only be used with CONF and/or PATCH specified. 
> If any value contains "+", it will be replaced by space.
> If just a single value is specified, it can contain spaces, e.g. 
> "COMPARE_BUILD=CONF=--enable-debug --with-special-sauce". (For 
> technical reasons, this is not possible if using multiple, 
> colon-separated key=value pairs).
>
> Values given in CONF and MAKE are appended to the normal configure 
> command line and make target list, respectively, when building the 
> second comparison round.
>
> The patch file, if specified, could be either absolute or relative to 
> TOPDIR.
>
> COMP_OPTS is additional options to pass to compare.sh.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8136695
> WebRev: 
> http://cr.openjdk.java.net/~ihse/JDK-8136695-compare_build/webrev.01
>
> /Magnus
>