[PATCH] ipa-sra: Consider the first parameter of methods safe to dereference

[Martin Jambor <mjambor@suse.cz>]

Hi,

Honza requested this after reviewing the patch that taught IPA-SRA
that REFERENCE_TYPEs are always non-NULL that the pass also handles
the first parameters of methods, this pointers, in the same way.  So
this patch does that.

The patch is undergoing bootstrap and testing on an x86_64-linux right
now.  OK if it passes?

Thanks,

Martin


gcc/ChangeLog:

2022-12-14  Martin Jambor  <mjambor@suse.cz>

	* ipa-sra.cc (create_parameter_descriptors): Consider the first
	parameter of a method safe to dereference.

gcc/testsuite/ChangeLog:

2022-12-14  Martin Jambor  <mjambor@suse.cz>

	* g++.dg/ipa/ipa-sra-6.C: New test.
---
 gcc/ipa-sra.cc                       |  7 +++-
 gcc/testsuite/g++.dg/ipa/ipa-sra-6.C | 62 ++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/ipa/ipa-sra-6.C

diff --git a/gcc/ipa-sra.cc b/gcc/ipa-sra.cc
index bcabdedfc6c..6fe336eeb19 100644
--- a/gcc/ipa-sra.cc
+++ b/gcc/ipa-sra.cc
@@ -1206,7 +1206,12 @@ create_parameter_descriptors (cgraph_node *node,
       if (POINTER_TYPE_P (type))
 	{
 	  desc->by_ref = true;
-	  desc->safe_ref = (TREE_CODE (type) == REFERENCE_TYPE);
+	  if (TREE_CODE (type) == REFERENCE_TYPE
+	      || (num == 0
+		  && TREE_CODE (TREE_TYPE (node->decl)) == METHOD_TYPE))
+	    desc->safe_ref = true;
+	  else
+	    desc->safe_ref = false;
 	  type = TREE_TYPE (type);
 
 	  if (TREE_CODE (type) == FUNCTION_TYPE
diff --git a/gcc/testsuite/g++.dg/ipa/ipa-sra-6.C b/gcc/testsuite/g++.dg/ipa/ipa-sra-6.C
new file mode 100644
index 00000000000..d6b7822533f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ipa/ipa-sra-6.C
@@ -0,0 +1,62 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-ipa-sra"  } */
+
+namespace {
+
+class C
+{
+
+  int mi;
+
+public:
+  C (int i)
+    : mi(i)
+  {}
+
+  void foo (int c);
+};
+
+volatile int vi;
+
+
+void __attribute__((noinline))
+C::foo (int cond)
+{
+  int i;
+  if (cond)
+    i = mi;
+  else
+    i = 0;
+  vi = i;
+}
+
+static C c_instance(1);
+}
+
+void __attribute__((noinline))
+bar (C *p, int cond)
+{
+  p->foo (cond);
+}
+
+
+class C *gp;
+
+void something(void);
+
+void
+baz (int cond)
+{
+  C c(vi);
+  gp = &c;
+  something ();
+  bar (gp, cond);
+}
+
+void
+hoo(void)
+{
+  gp = &c_instance;
+}
+
+/* { dg-final { scan-ipa-dump "Will split parameter" "sra" } } */
-- 
2.38.1