Fix ICE on view conversion between struct and integer

This happens from prepare_gimple_addressable for the variable to be marked
with DECL_NOT_GIMPLE_REG_P when its initialization is gimplified, so it's
apparently just a matter of setting the flag earlier.

gcc/
	* gimplify.cc (lookup_tmp_var): Add NOT_GIMPLE_REG boolean parameter
	and set DECL_NOT_GIMPLE_REG_P on the variable according to it.
	(internal_get_tmp_var): Add NOT_GIMPLE_REG boolean parameter and
	pass it in the call to lookup_tmp_var.
	(get_formal_tmp_var): Pass false in the call to lookup_tmp_var.
	(get_initialized_tmp_var): Likewise.
	(prepare_gimple_addressable): Call internal_get_tmp_var instead of
	get_initialized_tmp_var with NOT_GIMPLE_REG set to true.

gcc/testsuite/
	* gnat.dg/opt98.ads, gnat.dg/opt98.adb: New test.

2 files changed, 33 insertions, 0 deletions

diff --git a/gcc/testsuite/gnat.dg/opt98.adb b/gcc/testsuite/gnat.dg/opt98.adb
new file mode 100644
index 0000000..6d42338
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/opt98.adb
@@ -0,0 +1,14 @@
+-- { dg-do compile }
+-- { dg-options "-O -gnatws" }
+
+package body Opt98 is
+
+  function Func return Rec is
+    R :Rec;
+  begin
+    A := To_Address ((I => 0));
+    R := To_Rec (A);
+    return R;
+  end;
+
+end Opt98;
diff --git a/gcc/testsuite/gnat.dg/opt98.ads b/gcc/testsuite/gnat.dg/opt98.ads
new file mode 100644
index 0000000..fcc70577
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/opt98.ads
@@ -0,0 +1,19 @@
+with Ada.Unchecked_Conversion;
+with System;
+
+package Opt98 is
+
+  type Rec is record
+    I : Integer;
+  end record;
+
+  function To_Address is new Ada.Unchecked_Conversion (Rec, System.Address);
+
+  function To_Rec is new Ada.Unchecked_Conversion (System.Address, Rec);
+
+  A : System.Address with Atomic;
+
+  function Func return Rec;
+
+end Opt98;
+