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
