RFR: 8143219: AArch64 broken by 8141132: JEP 254: Compact Strings
tobias.hartmann at oracle.com
Thu Nov 19 15:08:28 UTC 2015
thanks for catching this!
On 19.11.2015 12:56, Andrew Haley wrote:
> Two things happened, one simple and one not-so-simple.
> Firstly, the string comparators now take a byte count (because it's a
> byte array now) rather than a char count.
> Secondly, string_indexOf needs to have a guard to make sure that
> substr.count <= string.count. This is guaranteed by
> LibraryCallKit::inline_string_indexOf but not by
> LibraryCallKit::inline_string_indexOfI. This is a subtle change, and
> was quite tricky to figure out. I have fixed it here in the AArch64
> back end.
I think this check should be done in inline_string_indexOfI() because other intrinsics may also depend on it (see macroAssembler_x86.cpp). Same applies to the "substr count == 0" check. One could probably factor out the checks and use them for both inline_string_indexOf* methods.
I'm moving some more runtime checks from the Java code into the intrinsics (see JDK-8142303 which is currently out for review on hotspot-compiler-dev).
If you want, I can take care of these checks as well.
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