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

Erik Joelsson erik.joelsson at oracle.com
Fri Mar 2 15:29:47 UTC 2018

This looks good to me.


On 2018-03-02 04:45, Magnus Ihse Bursie wrote:
> 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

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