> On 2 Feb 2016, at 07:00, Aleksey Shipilev <aleksey.shipi...@oracle.com> wrote: > > Anyone? This looks like a trivial fix. >
+1. The comment on stack logic is really helpful. Paul. > -Aleksey > > On 02/01/2016 10:47 PM, Aleksey Shipilev wrote: >> Hi, >> >> Please review the fix for a corner case in StringConcatFactory exactness >> check, which produces invalid bytecode: >> https://bugs.openjdk.java.net/browse/JDK-8148787 >> >> Note that this happens when all three things align: >> a) BSM is called directly, as Java method -- javac would never produce >> such a String concat shape; >> b) BC_SB_SIZED_EXACT strategy is used, so exactness check can be applied; >> c) -Djava.lang.invoke.stringConcat.debug=true is set, forcing >> exactness check to run; >> >> The issue is with exactness debug check using a temporary local variable >> when the local variable table is small (like it is in non-arg case). The >> code can be reformulated without using temporary variables, with a >> creative use of "swap" instruction. >> >> Ironically, the bug is within the debugging code, so we don't care about >> its performance at all: >> http://cr.openjdk.java.net/~shade/8148787/webrev.01/ >> >> Cheers, >> -Aleksey >> > >
