re PR rtl-optimization/18628 (miscompilation of switch statement in loop)

gcc/ChangeLog:
PR middle-end/18628
* cse.c (fold_rtx_mem): Don't fold a load from a jumptable into a
register.
gcc/testsuite/ChangeLog:
* gcc.dg/pr18628.c: New.

From-SVN: r96445