<AWT Dev> 8221405: Fix Windows 32bit awt build

Alexey Ivanov alexey.ivanov at oracle.com
Tue Mar 26 15:26:50 UTC 2019

Hi Thomas,

On 26/03/2019 14:41, Thomas Stüfe wrote:
> Hi Alexey,
> On Tue, Mar 26, 2019 at 2:36 PM Alexey Ivanov 
> <alexey.ivanov at oracle.com <mailto:alexey.ivanov at oracle.com>> wrote:
>     Hi Thomas,
>     Looks good, I'm not a reviewer though.
>     Could I also ask you to push this changeset to jdk/client [1]
>     instead of
>     jdk/jdk?
>     A small question: two prototypes are changed in debug_trace.h but
>     only
>     one is updated in debug_trace.c. Is it because the functions matching
>     the second prototype have already been updated with JNICALL?
> Not really sure I understand the question. There is no real 1:1 
> relationship between my change in .h and .c:

I mean there are two prototypes in the header:
1. typedef void (JNICALL *DTRACE_OUTPUT_CALLBACK)(const char * msg);
2. typedef void (JNICALL *DTRACE_PRINT_CALLBACK)(const char * file, int 
line, int argc, const char * fmt, va_list arglist);

1. In C, only the first one is updated:
static void JNICALL DTrace_PrintStdErr(const char *msg);
which corresponds to the first case. This shouldn't have caused build 
failure because the declarations in .h and .c matched.

2. I believe DTrace_VPrintln and DTrace_VPrint are the callbacks for the 
2nd prototype of DTRACE_PRINT_CALLBACK. They're received JNICALL under 
JDK-8214120 but the header hasn't been updated. This caused the build 

The prevent the build failure, it would be enough to update the 2nd 
declaration in the header. (Or alternatively, drop JNICALL from 
DTrace_VPrintln and DTrace_VPrint in .c file.)
For consistency, you're updating the 1st declaration as well.

> DTRACE_PRINTxx macros call _DTrace_Template() which expands to 
> DTrace_PrintFunction(). First argument is pointer to DTrace_VPrint(), 
> which is a function decorated with JNICALL. Hence the build error - 
> the type of the first argument of DTrace_PrintFunction is 
> DTRACE_PRINT_CALLBACK, which is a fkt pointer *without* JNICALL.
> So one way to fix this was to correct the DTRACE_PRINT_CALLBACK type 
> to be a fkt pointer pointing to a JNICALL decorated function.
> That means that I also needed to fix all functions whose pointers are 
> being passed around as DTRACE_PRINT_CALLBACK. But there only was one I 
> saw, DTrace_PrintStdErr().

 From the above, it looks this isn't necessary as DTrace_PrintStdErr() 

However, I think it's better to have both DTRACE_OUTPUT_CALLBACK and 
DTRACE_PRINT_CALLBACK consistent: either with JNICALL or without.

Looks fine to me!

> I'll push to jdk/client. Will that be transported to jdk/jdk 
> automatically?

Yes, it will.
Although I'm not sure how often they're synced.


> Cheers, Thomas
>     Regards,
>     Alexey
>     [1] http://hg.openjdk.java.net/jdk/client/
>     On 25/03/2019 13:09, Thomas Stüfe wrote:
>     > Hi all,
>     >
>     > Issue: https://bugs.openjdk.java.net/browse/JDK-8221405
>     > cr:
>     >
>     http://cr.openjdk.java.net/~stuefe/webrevs/8221405-windows32-awt-buildfixes/webrev.00/webrev/
>     >
>     > On 32bit windows, awt build did bitrot. Dtrace print callbacks
>     need to
>     > be declared with __stdcall. No other platform cares.
>     >
>     > Thanks, Thomas

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