From 241a2c498005207d52a3d64884e41953fc00275c Mon Sep 17 00:00:00 2001
From: Eric Botcazou <ebotcazou@adacore.com>
Date: Fri, 4 Dec 2020 10:04:56 +0100
Subject: [PATCH] Fix checking failure in IPA-SRA

This is a regression present on the mainline and 10 branch: on the one
hand, IPA-SRA does *not* disqualify accesses with zero size but, on the
other hand, it checks that accesses present in the tree have a (strictly)
positive size, thus trivially yielding an ICE in some cases.

gcc/ChangeLog:
	* ipa-sra.c (verify_access_tree_1): Relax assertion on the size.

gcc/testsuite/ChangeLog:
	* gnat.dg/opt91.ads, gnat.dg/opt91.adb: New test.
	* gnat.dg/opt91_pkg.ads, gnat.dg/opt91_pkg.adb: New helper.
---
 gcc/ipa-sra.c                       |  2 +-
 gcc/testsuite/gnat.dg/opt91.adb     | 11 +++++++++++
 gcc/testsuite/gnat.dg/opt91.ads     | 10 ++++++++++
 gcc/testsuite/gnat.dg/opt91_pkg.adb | 12 ++++++++++++
 gcc/testsuite/gnat.dg/opt91_pkg.ads | 19 +++++++++++++++++++
 5 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gnat.dg/opt91.adb
 create mode 100644 gcc/testsuite/gnat.dg/opt91.ads
 create mode 100644 gcc/testsuite/gnat.dg/opt91_pkg.adb
 create mode 100644 gcc/testsuite/gnat.dg/opt91_pkg.ads

diff --git a/gcc/ipa-sra.c b/gcc/ipa-sra.c
index 82acc6a21cb..7adc4b688f3 100644
--- a/gcc/ipa-sra.c
+++ b/gcc/ipa-sra.c
@@ -1480,7 +1480,7 @@ verify_access_tree_1 (gensum_param_access *access, HOST_WIDE_INT parent_offset,
 {
   while (access)
     {
-      gcc_assert (access->offset >= 0 && access->size > 0);
+      gcc_assert (access->offset >= 0 && access->size >= 0);
 
       if (parent_size != 0)
 	{
diff --git a/gcc/testsuite/gnat.dg/opt91.adb b/gcc/testsuite/gnat.dg/opt91.adb
new file mode 100644
index 00000000000..b0132f82d09
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/opt91.adb
@@ -0,0 +1,11 @@
+-- { dg-do compile }
+-- { dg-options "-O2 -fchecking=1" }
+
+package body Opt91 is
+
+   function Custom_Image (Self : True_Relation_Rec) return String is
+   begin
+      return "<True>";
+   end;
+
+end Opt91;
diff --git a/gcc/testsuite/gnat.dg/opt91.ads b/gcc/testsuite/gnat.dg/opt91.ads
new file mode 100644
index 00000000000..b31aa8de350
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/opt91.ads
@@ -0,0 +1,10 @@
+with Opt91_Pkg; use Opt91_Pkg;
+
+package Opt91 is
+
+   type True_Relation_Rec is null record;
+   function Custom_Image (Self : True_Relation_Rec) return String;
+
+   package True_Relation is new Pure_Relation (Ty => True_Relation_Rec);
+
+end Opt91;
diff --git a/gcc/testsuite/gnat.dg/opt91_pkg.adb b/gcc/testsuite/gnat.dg/opt91_pkg.adb
new file mode 100644
index 00000000000..5b95fb2e165
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/opt91_pkg.adb
@@ -0,0 +1,12 @@
+package body Opt91_Pkg is
+
+   package body Pure_Relation is
+
+      overriding function Custom_Image (Self : Rel) return String is
+      begin
+         return Custom_Image (Self.Rel);
+      end Custom_Image;
+
+   end Pure_Relation;
+
+end Opt91_Pkg;
diff --git a/gcc/testsuite/gnat.dg/opt91_pkg.ads b/gcc/testsuite/gnat.dg/opt91_pkg.ads
new file mode 100644
index 00000000000..9bfd0f05b3d
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/opt91_pkg.ads
@@ -0,0 +1,19 @@
+package Opt91_Pkg is
+
+   type Base_Relation is abstract tagged null record;
+
+   function Custom_Image (Self : Base_Relation) return String is abstract;
+
+   generic
+      type Ty is private;
+      with function Custom_Image (Self : Ty) return String is <>;
+   package Pure_Relation is
+
+      type Rel is new Base_Relation with record
+         Rel : Ty;
+      end record;
+
+      overriding function Custom_Image (Self : Rel) return String;
+   end Pure_Relation;
+
+end Opt91_Pkg;
-- 
2.30.2