[PATCH] ipa-sra: Fix address escape case when detecting Fortran descriptors

[Martin Jambor <mjambor@suse.cz>]

Hi,

The discussion about scan_expr_access in ipa-sra.cc brought my
attention to a missing case of handling an ADDR_EXPR.  As the added
testcase shows, the heuristics which looks for parameters which are
local variables that are only written to and passed by reference in
calls can miss a case where the address of the variable in question is
stored elsewhere in an assignment.

This patch adds that case to the function and also adds the
optimization that Richi suggested, i.e. bailing out early on simple
SSA_NAMEs and constant trees.

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 (loaded_decls): Adjust comment.
	(scan_expr_access): Also detect assignments of address of local
	variables to a variable.  Bail out early on SSA_NAMEs and
	constants as an optimization.

gcc/testsuite/ChangeLog:

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

	* gcc.dg/ipa/ipa-sra-29.c: New test.
---
 gcc/ipa-sra.cc                        | 16 ++++++++++-
 gcc/testsuite/gcc.dg/ipa/ipa-sra-29.c | 38 +++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.dg/ipa/ipa-sra-29.c

diff --git a/gcc/ipa-sra.cc b/gcc/ipa-sra.cc
index 93f5e34b15c..bcabdedfc6c 100644
--- a/gcc/ipa-sra.cc
+++ b/gcc/ipa-sra.cc
@@ -592,7 +592,8 @@ namespace {
 
 hash_map<tree, gensum_param_desc *> *decl2desc;
 
-/* All local DECLs ever loaded from.  */
+/* All local DECLs ever loaded from of and of those that have their address
+   assigned to a variable.  */
 
 hash_set <tree> *loaded_decls;
 
@@ -1743,6 +1744,19 @@ scan_expr_access (tree expr, gimple *stmt, isra_scan_context ctx,
   bool deref = false;
   bool reverse;
 
+  if (TREE_CODE (expr) == ADDR_EXPR)
+    {
+      if (ctx == ISRA_CTX_ARG)
+	return;
+      tree t = get_base_address (TREE_OPERAND (expr, 0));
+      if (TREE_CODE (t) == VAR_DECL && !TREE_STATIC (t))
+	loaded_decls->add (t);
+      return;
+    }
+  if (TREE_CODE (expr) == SSA_NAME
+      || CONSTANT_CLASS_P (expr))
+    return;
+
   if (TREE_CODE (expr) == BIT_FIELD_REF
       || TREE_CODE (expr) == IMAGPART_EXPR
       || TREE_CODE (expr) == REALPART_EXPR)
diff --git a/gcc/testsuite/gcc.dg/ipa/ipa-sra-29.c b/gcc/testsuite/gcc.dg/ipa/ipa-sra-29.c
new file mode 100644
index 00000000000..aee45ea0e8f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ipa/ipa-sra-29.c
@@ -0,0 +1,38 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-ipa-sra-details"  } */
+
+struct S
+{
+  float f;
+  int i;
+  void *p;
+};
+
+extern struct S *gp;
+int baz (float);
+
+static int
+__attribute__((noinline))
+bar (struct S *p)
+{
+  if (p->i != 6)
+    __builtin_abort ();
+
+  return baz(p->f);
+}
+
+int
+foo (void)
+{
+  struct S s;
+
+  gp = &s;
+  s.f = 7.4;
+  s.i = 6;
+  s.p = &s;
+
+  bar (&s);
+  return 0;
+}
+
+/* { dg-final { scan-ipa-dump-not "Variable constructed just to be passed to calls" "sra" } } */
-- 
2.38.1