Erik Trimble said the following on 04/30/11 10:27:
On 4/29/2011 5:17 PM, David Holmes wrote:
David Katleman said the following on 04/30/11 09:13:
On 4/29/2011 3:59 PM, Omair Majid wrote:
http://cr.openjdk.java.net/~omajid/webrevs/gcc-46-support/
The patch adds support for building hotspot with gcc 4.6. gcc 4.6
changed how arguments are handled. It now treats -export-dynamic as
it treats any other -efoo option: it thinks xport-dynamic is the
entry point and passes this information to the linker. Since
-export-dynamic is not passed to the linker, not all symbols will be
exported by the linker. The bfd-based linker, given the invalid
entry point xport-dynamic, simply ignores it. The gold linker,
however, crashes causing the build to fail.
Since -export-dynamic is a linker option, the correct way to pass it
is using -Wl,-export-dynamic (or -Xlinker -export-dynamic). We have
had this patch in IcedTea6 for a while now, but it would be nice if
this was in OpenJDK too.
Seems like your change should be surrounded by an ifneq that enables
your change for 4.6 and later
Changing the use of a linker option:
-foo
to
-Xlinker -foo (or -Wl,-foo)
is fully compatible and preferable. We've been making a number of such
changes ourselves (-Xlinker form) because they are needed when working
with some of the cross-compilers we use for embedded.
David Holmes
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Example elsewhere in the file
129 # Except for a few acceptable ones
130 # Since GCC 4.3, -Wconversion has changed its meanings to warn
these implicit
131 # conversions which might affect the values. To avoid that, we
need to turn
132 # it off explicitly.
133 ifneq "$(shell expr \( $(CC_VER_MAJOR) \> 4 \) \| \( \(
$(CC_VER_MAJOR) = 4 \) \& \( $(CC_VER_MINOR) \>= 3 \) \))" "0"
134 ACCEPTABLE_WARNINGS = -Wpointer-arith -Wsign-compare
135 else
136 ACCEPTABLE_WARNINGS = -Wpointer-arith -Wconversion -Wsign-compare
137 endif
Thanks
Dave
Presuming that the changes are still valid for a GCC and early libc in
the 3.x range (i.e. older 2.4-based releases), then it's OK to not use
ifneq
Otherwise, we should use ifneq to cover the versions of GCC/libc where
this is a valid option.
We (Oracle) and others still support older Linux distros, so we do need
to be careful not to break anything unless we specifically mean to (and,
have a good reason to cause such breakage).
As long as the gcc version recognizes -Xlinker (and/or -Wl,) then as I
said changing from direct use of -foo to "-Xlinker -foo" is 100% compatible.
We already use -Xlinker and -Wl, all over the place! So this change
should not have any compatibility issues whatsoever.
David
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