[gcc r13-4705] ipa-sra: Fix address escape case when detecting Fortran descriptors

[gcc r13-4705] ipa-sra: Fix address escape case when detecting Fortran descriptors

[Martin Jambor]

https://gcc.gnu.org/g:6539bbc14836b8e0fa08944be2c069b58bed9455

commit r13-4705-g6539bbc14836b8e0fa08944be2c069b58bed9455
Author: Martin Jambor <mjambor@suse.cz>
Date:   Wed Dec 14 19:01:11 2022 +0100

    ipa-sra: Fix address escape case when detecting Fortran descriptors
    
    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.
    
    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.

Diff:
---
 gcc/ipa-sra.cc                        | 16 ++++++++++++++-
 gcc/testsuite/gcc.dg/ipa/ipa-sra-29.c | 38 +++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 1 deletion(-)

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" } } */