http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50672
--- Comment #17 from vries at gcc dot gnu.org 2012-08-01 23:14:36 UTC --- The test-case from comment 15 passes with r190033, and fails with r190034. block 10 contains: ... # .MEMD.2233_20 = PHI <.MEMD.2233_5(11), .MEMD.2233_10(12)> ... and is replaced by block 9 by tail-merge. Quoted from http://gcc.gnu.org/ml/gcc-patches/2011-10/msg00977.html: ... Whoever unlinks the vuse (by removing its definition) has to replace it with something valid, which is either the bare symbol .MEM, or the VUSE associated with the removed VDEF (thus, as unlink_stmt_vdef does). ... So the def of _20 is removed, and it's uses need to be handled. That is done by release_last_vdef which was part of the fix for this bug, and is removed in r190034.
