openmp: Set cfun->calls_alloca when needed in OpenMP outlined regions [PR97294]

openmp: Set cfun->calls_alloca when needed in OpenMP outlined regions [PR97294]

The following testcase FAILs, because we don't mark the child OpenMP function
as cfun->calls_alloca when it does call alloca.  When optimizing, during DCE we
reset those flags and recompute them again, but with -O0 DCE is not performed.

Fixed by calling notice_special_calls when moving insns to the child function.

cfun->calls_alloca is normally set during gimplification and most of the
alloca calls omp-low.c does go through the gimplifier, but one spot didn't
and built the gcall directly, so that one needs to set calls_alloca too.

2020-10-08  Jakub Jelinek  <jakub@redhat.com>

	PR sanitizer/97294
	* tree-cfg.c (move_block_to_fn): Call notice_special_calls on
	call stmts being moved into dest_cfun.
	* omp-low.c (lower_rec_input_clauses): Set cfun->calls_alloca when
	adding __builtin_alloca_with_align call without gimplification.

	* gcc.dg/asan/pr97294.c: New test.

(cherry picked from commit 273b30c8e93f043f65a04e0ff2ec305b311e98fa)