tree-optimization/109002 - partial PRE miscompilation

tree-optimization/109002 - partial PRE miscompilation

Partial PRE ends up miscompiling the testcase in PR109002, likely
involving a corner case when inifinite loops are involved.  The
following avoids the miscompilation by addressing a long-standing
oddity that manifests in odd partial partial redundancies eliminated
that are full redundancies.  The oddity is that while we properly
PHI translate the PA_IN set from the successors when computing
PA_OUT but we fail to do the same for ANTIC_IN which is supposed
to be unioned.  That results in expressions with wrong virtual
operands being placed in the PA_OUT/IN sets and the pruning
machinery to go wrong because it assumes the expressions in the
sets have virtual operands that are valid in the respective blocks.

	PR tree-optimization/109002
	* tree-ssa-pre.cc (compute_partial_antic_aux): Properly
	PHI-translate ANTIC_IN.

	* gcc.dg/torture/pr109002.c: New testcase.