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.

3 files changed, 44 insertions, 0 deletions

diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index b054961..b3e2468 100644
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -5112,6 +5112,7 @@ lower_rec_input_clauses (tree clauses, gimple_seq *ilist, gimple_seq *dlist,
 		  atmp = builtin_decl_explicit (BUILT_IN_ALLOCA_WITH_ALIGN);
 		  stmt = gimple_build_call (atmp, 2, x,
 					    size_int (DECL_ALIGN (var)));
+		  cfun->calls_alloca = 1;
 		  tmp = create_tmp_var_raw (ptr_type_node);
 		  gimple_add_tmp_var (tmp);
 		  gimple_call_set_lhs (stmt, tmp);
diff --git a/gcc/testsuite/gcc.dg/asan/pr97294.c b/gcc/testsuite/gcc.dg/asan/pr97294.c
new file mode 100644
index 0000000..6de6c3e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/asan/pr97294.c
@@ -0,0 +1,41 @@
+/* PR sanitizer/97294 */
+/* { dg-do compile { target fopenmp } } */
+/* { dg-skip-if "" { *-*-* } { "*" } { "-O0" } } */
+/* { dg-options "-O0 -fsanitize=address -fopenmp" } */
+/* { dg-final { scan-assembler "foo._omp_fn.\[0-9]\[1-9]*:.*call\[ \t]\*__*asan_allocas_unpoison.*\.size\[ \t]\*foo._omp_fn.\[0-9]\[1-9]*," { target x86_64-*-linux* i?86-*-linux* } } } */
+
+__attribute__((noipa)) void
+foo (int *p, int n)
+{
+  int i;
+  #pragma omp parallel for num_threads(2) reduction(+:p[:n])
+  for (i = 0; i < 10; i++)
+    {
+      p[0]++;
+      p[n - 1] += 2;
+    }
+}
+
+__attribute__((noipa)) void
+bar (void)
+{
+  unsigned char buf[1024];
+  int i;
+  asm volatile ("" : : "r" (&buf[0]) : "memory");
+  for (i = 0; i < 1024; i++)
+    buf[i] = i;
+  asm volatile ("" : : "r" (&buf[0]) : "memory");
+}
+
+int
+main ()
+{
+  int p[50], i;
+  for (i = 0; i < 50; i++)
+    p[i] = 0;
+  foo (p, 50);
+  bar ();
+  if (p[0] != 10 || p[49] != 20)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index 4064417..5caf3b6 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -7220,6 +7220,8 @@ move_block_to_fn (struct function *dest_cfun, basic_block bb,
       free_stmt_operands (cfun, stmt);
       push_cfun (dest_cfun);
       update_stmt (stmt);
+      if (is_gimple_call (stmt))
+	notice_special_calls (as_a <gcall *> (stmt));
       pop_cfun ();
     }