[9] RFR: 8044538: assert(which != imm_operand) failed: instruction is not a movq reg, imm64

Vladimir Kozlov vladimir.kozlov at oracle.com
Wed Jun 4 18:30:21 UTC 2014

Looks good. PrintRelocations flag is used very rare, that is why it 
rotted. Please, add jreg test (use -XX:+IgnoreUnrecognizedVMOptions). 
Since this debug flag almost never used backporting the fix only into 8u 
may be enough.


On 6/4/14 1:30 AM, Tobias Hartmann wrote:
> Hi,
> please review the following patch for bug 8044538.
> *Problem*
> Executing a debug build of HotSpot with the flags -XX:+PrintRelocations
> -Xcomp hits a ShouldNotReachHere() or an assert in
> Assembler::locate_operand(..) stating that the instruction for which we
> try to find the operand is not valid.
> The problem occurs while printing the relocation entries for a C2
> compiled function. The C2 compiler adds internal_word_type relocations
> for the jump table entries in the constant section of a method (see
> Compile::ConstantTable::fill_jump_table(...)). These relocations are
> processed by RelocIterator::print_current(...) and
> internal_word_Relocation::target().
> Relocation::pd_get_address_from_code() then tries to retrieve the
> address from an instruction but fails because the relocation points into
> the constant section only containing the target address.
> Bug: https://bugs.openjdk.java.net/browse/JDK-8044538
> *Solution*
> The implementation of internal_word_Relocation::target() is changed to
> check if the relocation points into the constant section and if so
> directly returns the target address instead of trying to retrieve it
> from an instruction. The same is already done in
> internal_word_Relocation::fix_relocation_after_move(..).
> Webrev: http://cr.openjdk.java.net/~thartmann/8044538/webrev.00/
> *Tests*
> Failing configuration, JPRT
> Apparently this did not show up for any of our tests. Do we need an
> additional test for this?
> Since it already fails for JDK 7 and 8. Should we backport the patch?
> Thanks,
> Tobias

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