Fix ipa-prop wrt volatile memory accesses

[Jan Hubicka <hubicka@kam.mff.cuni.cz>]

Hi,
this patch prevents ipa-prop from propagating aggregates when load is
volatile.  Martin, does this look OK?  It seem to me that ipa-prop may
need some additional volatile flag checks.

Bootstrapped/regtested x86_64-linux, OK?

Honza

gcc/ChangeLog:

2022-06-10  Jan Hubicka  <hubicka@ucw.cz>

	PR ipa/105739
	* ipa-prop.cc (ipa_load_from_parm_agg): Disqualify volatile memory
	accesses.

gcc/testsuite/ChangeLog:

2022-06-10  Jan Hubicka  <hubicka@ucw.cz>

	* gcc.dg/ipa/pr105739.c: New test.

diff --git a/gcc/ipa-prop.cc b/gcc/ipa-prop.cc
index afd9222b5a2..c037668e7d8 100644
--- a/gcc/ipa-prop.cc
+++ b/gcc/ipa-prop.cc
@@ -1112,6 +1112,10 @@ ipa_load_from_parm_agg (struct ipa_func_body_info *fbi,
   if (!base)
     return false;
 
+  /* We can not propagate across volatile loads.  */
+  if (TREE_THIS_VOLATILE (op))
+    return false;
+
   if (DECL_P (base))
     {
       int index = ipa_get_param_decl_index_1 (descriptors, base);
diff --git a/gcc/testsuite/gcc.dg/ipa/pr105739.c b/gcc/testsuite/gcc.dg/ipa/pr105739.c
new file mode 100644
index 00000000000..8dbe8fc2494
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ipa/pr105739.c
@@ -0,0 +1,30 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+
+__attribute__((noinline))
+static int
+test2(int a)
+{
+        if (__builtin_constant_p (a))
+                __builtin_abort ();
+        return a;
+}
+static int
+test(int *a)
+{
+        int val = *(volatile int *)a;
+        if (__builtin_constant_p (val))
+                __builtin_abort ();
+        if (val)
+          return test2(val);
+        return 0;
+}
+int a;
+int
+main()
+{
+        a = 0;
+        return test (&a);
+}
+/* { dg-final { scan-tree-dump "test2" "optimized" } } */