RFR: JDK-8198862 Stop doing funky compilation stuff for dtrace

[Magnus Ihse Bursie]

On 2018-03-02 12:10, Magnus Ihse Bursie wrote:
> On 2018-03-02 03:01, David Holmes wrote:
>> Hi Magnus,
>>
>> On 1/03/2018 10:48 AM, Magnus Ihse Bursie wrote:
>>> We're doing a lot of weird compilation stuff for dtrace. With this 
>>> patch, most of the weirdness is removed. The remaining calls to 
>>> $(CC) -E has been changed to $(CPP) to clarify that we do not 
>>> compile, we just use the precompiler.
>>>
>>> One of the changes I made was to actually split up the last and 
>>> final dtrace call into a separate preprocessing step. However, this 
>>> uses the solaris studio preprocessor instead of the ancient system 
>>> preprocessor, which has changed behavior. A string like (&``_var) is 
>>> now expanded to (& ` ` _var), which is not accepted by dtrace. :-( I 
>>> have worked around this by adding the preprocessed output, without 
>>> the spaces, in two places. If anyone wants to dig deeper into dtrace 
>>> script file syntax, or C preprocessor magic, to avoid this, let me 
>>> know... (I'll just state that the "obvious" solution of sending -Xs 
>>> to the preprocessor to get old-style behavior does not work: this 
>>> just makes the solaris studio preprocessor call the ancient 
>>> preprocessor in turn, and we've gained nothing...)
>>>
>>> Bug: https://bugs.openjdk.java.net/browse/JDK-8198862
>>> WebRev: 
>>> http://cr.openjdk.java.net/~ihse/JDK-8198862-stop-doing-funky-dtrace-compilation-stuff/webrev.01 
>>
>>
>>
>> Why did you rename generateJvmOffsetsMain.c to 
>> generateJvmOffsetsMain.cpp? It isn't a C++ program, it's just a C 
>> program.
> Yes, but so are generateJvmOffsets.cpp. :-& There was no point in 
> mixing a .cpp and .c file for this trivial build tool helper. In fact, 
> I don't even understand why they are two separate files -- if I get 
> the blessings from someone in hotspot, I'll gladly just concatenate 
> them into a single file.
Come to think about it, I don't care about the hotspot group's blessing. 
;-) I just moved the main function into the generateJvmOffsets.cpp file. 
It was just silly having it as a separate file.

>
>> !     # Since we cannot generated JvmOffsets.cpp as part of the 
>> gensrc step,
>>
>> Comment doesn't read right.
> Typo, should be "generate". I'll fix.

Updated.

I also restored the extra ( ) in ExecuteWithLog with redirection, and 
added an additional ( ) for one case that was previously missing one.

Finally I also added the changes to dtrace that Erik requested for 
JDK-8198859, but which was already pushed by that time.

New webrev:
http://cr.openjdk.java.net/~ihse/JDK-8198862-stop-doing-funky-dtrace-compilation-stuff/webrev.02

/Magnus