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I have looked at the build changes and they look good.

Will you file followups for each component team to look over their exported symbols, at least for the libraries with $(EXPORT\_ALL\_SYMBOLS)? It sure looks like there is some technical debt laying around here.

/Erik


On 2018-03-23 06:56, Magnus Ihse Bursie wrote:

With modern compilers, we can use compiler directives (such as \_attribute\_\_((visibility("default"))), or \_\_declspec(dllexport)) to control symbol visibility, directly in the source code. This has historically not been present on all compilers, so we had to resort to using mapfiles (also known as linker scripts).

This is no longer the case. Now all compilers we use support symbol visibility directives, in one form or another. We should start using this. Since this has been the only way to control symbol visibility on Windows, for most of the shared code, we already have proper JNIEXPORT decorations in place.

If we fix the remaining platform-specific files to have proper JNIEXPORT tagging, then we can finally get rid of mapfiles.

This fix removed mapfiles for all JDK libraries. It does not touch hotspot libraries nor JDK executables; they will have to wait for a future fix -- this was complex enough. This change will not have any impact on macosx, since we do not use mapfiles there, but instead export all symbols. (This is not a good idea, but I'll address that separately.) This change will also have a minimal impact on Windows. The only reason Windows is impacted at all, is that some changes needed by Solaris and Linux were simpler to fix for all platforms.

I have strived for this change to have no impact on the actual generated code. Unfortunately, this was not possible to fully achieve. I do not believe that these changes will have any actual impact on the product, though. I will present the differences more in detail further down. Those who are not interested can probably skip that.

The patch has passed tier1 testing and is currently running tier2 and tier3\. Since the running code is more or less (see caveat below) unmodified, I don't expect any testing issues.

Bug: https://bugs.openjdk.java.net/browse/JDK-8200178
WebRev: http://cr.openjdk.java.net/\~ihse/JDK-8200178-remove-mapfiles/webrev.01

Details on changes:
Most of the source code changes are (unsurprisingly) in java.base and java.desktop. Remaining changes are in jdk.crypto.ucrypto, jdk.hotspot.agent, jdk.jdi and jdk.jdwp.agent.

Source code changes does almost to 100% consists in decorating an exported function with JNIEXPORT. I have also followed the long-standing convention of adding JNICALL. This is a no-op on non-Windows platforms, so for most of the changes this is purely cosmetic (and possibly adding in robustness, should the function ever be used on Windows in the future). I have also followed the stylistic convention of putting "JNIEXPORT JNICALL" on a separate line. For some functions, however, this might cause a change in calling convention on Windows. Since this can not apply to exported functions on Windows (otherwise they would already have had JNIEXPORT), I do not think this matters anything.

A few libraries did not have a mapfile, on Linux and/or Solaris. This actually meant that all symbols were exported. It is highly unclear if this was known and intended by the original make rule writer. I have emulated this by adding the flag $(EXPORT\_ALL\_SYMBOLS) to these libraries. Hopefully, we can remove this flag and fix proper exported symbols in the future.

I have run the complete build using COMPARE\_BUILD, and made a thourough analysis of the differences for Linux and Solaris. All native libraries have symbol differences, but most of them are trivial and/or harmless. As a result, most libraries have disasm differences as well, but these too seem trivial and harmless. The differences in symbols that are common to all libraries include:
\* Internal symbols such as \_\_bss\_start, \_edata, \_end and \_fini are now global. (They are imported as such from the compiler libraries/archives, and we have no linker script to override this behavior).
\* The versioning tag SUNWprivate\_1.1 is not included, and thus neither the .gnu.version\_d symbol.
\* There are a few differences in the symbol and/or mangling of some local functions. I'm not sure what's causing this,
but it's unlikely to have any effect on the product.

Another common source for change in symbols is due to previous platform differences. For instance, if we had "JNIEXPORT int JNICALL do\_foo() { ... }", but do\_foo was not in the mapfile, the symbol was exported on Windows but not on Linux and Solaris. (Presumable since it was not needed there, even though it was compiled for those platforms as well.) Now, with the mapfiles gone, do\_foo() will be exported on all platforms. And contrary, functions that are compiled on all platforms, and were exported in mapfiles, but now have gotten an JNIEXPORT decoration, will now be visible even on Windows. (This accounts for half of the noticed symbol differences on Windows.) I could have made the JNIEXPORT conditional on OS, but I didn't think the mess in source code were worth the keeping of binary confidence with the old build.

A third common source for change in symbols is due to exported functions "leaking" across library borders. For instance, some functions in java.desktop is compiled in both libawt\_xawt and libawt\_headless, but they were previously only included in the mapfile for one of these libraries. Now, since the visibility is determined by the source code itself, it gets exported in both libraries. A variant of this is when a library depends on another JDK library, and includes the header file from that other library, which in turn declares a function as JNIEXPORT. This will cause the including library to also export the function. This accounts for the other half of the changes on Windows. A typical example of this is that multiple libraries now re-export hotspot symbols from libjvm.so, like jio\_fprintf. (I have not listed the libjvm re-exports below.)

Note that Java\_java\_io\_FileOutputStream\_close0 in java.base/unix/native/libjava/FileOutputStream\_md.c is no longer exported,
and can probably be removed.

Here is a detailed table showing and accounting for all the remaining differences found on Linux and Solaris:
java.base/unix/native/libjava: Java\_java\_io\_FileOutputStream\_close0 is now also exported on unix platforms due to JNIEXPORT.

java.base/jspawnlauncher: On solaris, we also include libjava/childproc.o, which
now exports less functions than it used to (it used to export all functions, now it is compiled with visibility=hidden).

java.base/java(w).exe: Is now also exporting the following symbols due to added JNIEXPORT in libjli on Windows:
(Yes, executables can export symbols on Windows. Confusing, I know.)
JLI\_AddArgsFromEnvVar
JLI\_CmdToArgs
JLI\_GetAppArgIndex
JLI\_GetStdArgc
JLI\_GetStdArgs
JLI\_InitArgProcessing
JLI\_Launch
JLI\_List\_add
JLI\_List\_new
JLI\_ManifestIterate
JLI\_MemAlloc
JLI\_MemFree
JLI\_PreprocessArg
JLI\_ReportErrorMessage
JLI\_ReportErrorMessageSys
JLI\_ReportExceptionDescription
JLI\_ReportMessage
JLI\_SetTraceLauncher
JLI\_StringDup

java.desktop:/libawt\_xawt: The following symbols are now also exported on linux and solaris due to JNIEXPORT:
awt\_DrawingSurface\_FreeDrawingSurfaceInfo
awt\_DrawingSurface\_GetDrawingSurfaceInfo
awt\_DrawingSurface\_Lock
awt\_DrawingSurface\_Unlock
awt\_GetColor

The following symbols are now also exported on linux and solaris due to JNIEXPORT (they were previously
exported only in libawt):
Java\_sun\_awt\_DebugSettings\_setCTracingOn\_\_Z
Java\_sun\_awt\_DebugSettings\_setCTracingOn\_\_ZLjava\_lang\_String\_2
Java\_sun\_awt\_DebugSettings\_setCTracingOn\_\_ZLjava\_lang\_String\_2I
Java\_sun\_awt\_X11GraphicsConfig\_getNumColors

java.desktop:/libawt\_headless: The following symbols are now also exported due to JNIEXPORT (they were previously
exported only in libawt\_xawt and/or libawt):
Java\_sun\_java2d\_opengl\_GLXGraphicsConfig\_getGLXConfigInfo
Java\_sun\_java2d\_opengl\_GLXGraphicsConfig\_getOGLCapabilities
Java\_sun\_java2d\_x11\_X11PMBlitLoops\_updateBitmask
Java\_sun\_java2d\_x11\_X11SurfaceData\_isShmPMAvailable
X11SurfaceData\_GetOps

java.desktop/libawt: The following symbols are now also exported on Windows, due to added
JNIEXPORT:
SurfaceData\_InitOps
mul8table
div8table
doDrawPath
doFillPath
g\_CMpDataID
initInverseGrayLut
make\_dither\_arrays
make\_uns\_ordered\_dither\_array
path2DFloatCoordsID
path2DNumTypesID
path2DTypesID
path2DWindingRuleID
sg2dStrokeHintID
std\_img\_oda\_blue
std\_img\_oda\_green
std\_img\_oda\_red
std\_odas\_computed
sunHints\_INTVAL\_STROKE\_PURE

java.desktop/libawt on solaris:
A number of "#pragma weak" directives was previously overridden by the mapfile.
Now these directives are respected, so these symbols are now weak instead of local:
ByteGrayToIntArgbPreConvert\_F
ByteGrayToIntArgbPreScaleConvert\_F
IntArgbBmToFourByteAbgrPreScaleXparOver\_F
IntArgbToIntRgbXorBlit\_F
IntBgrToIntBgrAlphaMaskBlit\_F

java.desktop/libawt on solaris: These are now also exported due to JNIEXPORT in libmlib\_image.
j2d\_mlib\_ImageCreate
j2d\_mlib\_ImageCreateStruct
j2d\_mlib\_ImageDelete

java.desktop/libawt on solaris: This is now also exported due to JNIEXPORT:
GrPrim\_CompGetXorColor
SurfaceData\_GetOpsNoSetup
SurfaceData\_IntersectBoundsXYWH
SurfaceData\_SetOps
Transform\_GetInfo
Transform\_transform

java.desktop/libsplashscreen: JNI\_OnLoad is now exported on linux and solaris due to JNIEXPORT.
libspashscreen also had JNIEXPORT (actually a pure \_declspec(dllexport)) but no JNICALL, which I added as
a part of converting to JNIEXPORT. The same goes for libmlib\_image .

jdk.sctp/libsctp: handleSocketError is now exported on linux and solaris due to JNIEXPORT in libnio.

java.instrument:/libinstrument: Agent\_OnUnload is now also exported on linux and solaris platforms due to JNIEXPORT.
JLI\_ManifestIterate is now also exported on Windows, due to added JNIEXPORT in libjli.

jdk.management/libmanagement\_ext: Java\_com\_sun\_management\_internal\_Flag\_setDoubleValue is now also exported on linux and solaris platforms due to JNIEXPORT.

/Magnus