[Ada] Fix portability issues in access to subprograms

This patch improves the portability of the code generated by the
compiler for access to subprograms. Written by Richard Kenner.

2019-09-18  Javier Miranda  <miranda@adacore.com>

gcc/ada/

	* exp_ch4.adb (Expand_N_Op_Eq): The frontend assumes that we can
	do a bit-for-bit comparison of two access to protected
	subprogram pointers. However, there are two reasons why we may
	not be able to do that: (1) there may be padding bits for
	alignment before the access to subprogram, and (2) the access to
	subprogram itself may not be compared bit-for- bit because the
	activation record part is undefined: two pointers are equal iff
	the subprogram addresses are equal. This patch fixes it by
	forcing a field-by-field comparison.
	* bindgen.adb (Gen_Adainit): The type No_Param_Proc is defined
	in the library as having Favor_Top_Level, but when we create an
	object of that type in the binder file we don't have that
	pragma, so the types are different. This patch fixes this issue.
	* libgnarl/s-interr.adb, libgnarl/s-interr__hwint.adb,
	libgnarl/s-interr__sigaction.adb, libgnarl/s-interr__vxworks.adb
	(Is_Registered): This routine erroneously assumes that the
	access to protected subprogram is two addresses. We need to
	create the same record that the compiler makes to ensure that
	any padding is the same. Then we have to look at just the first
	word of the access to subprogram. This patch fixes this issue.

From-SVN: r275856

gcc/ada/ChangeLog

+2019-09-18  Javier Miranda  <miranda@adacore.com>
+
+	* exp_ch4.adb (Expand_N_Op_Eq): The frontend assumes that we can
+	do a bit-for-bit comparison of two access to protected
+	subprogram pointers. However, there are two reasons why we may
+	not be able to do that: (1) there may be padding bits for
+	alignment before the access to subprogram, and (2) the access to
+	subprogram itself may not be compared bit-for- bit because the
+	activation record part is undefined: two pointers are equal iff
+	the subprogram addresses are equal. This patch fixes it by
+	forcing a field-by-field comparison.
+	* bindgen.adb (Gen_Adainit): The type No_Param_Proc is defined
+	in the library as having Favor_Top_Level, but when we create an
+	object of that type in the binder file we don't have that
+	pragma, so the types are different. This patch fixes this issue.
+	* libgnarl/s-interr.adb, libgnarl/s-interr__hwint.adb,
+	libgnarl/s-interr__sigaction.adb, libgnarl/s-interr__vxworks.adb
+	(Is_Registered): This routine erroneously assumes that the
+	access to protected subprogram is two addresses. We need to
+	create the same record that the compiler makes to ensure that
+	any padding is the same. Then we have to look at just the first
+	word of the access to subprogram. This patch fixes this issue.
+
 2019-09-18  Bob Duff  <duff@adacore.com>
 
 	* exp_ch5.adb (Expand_Assign_Array_Loop_Or_Bitfield): The call

gcc/ada/bindgen.adb

@@ -524,6 +524,7 @@ package body Bindgen is
         and then not Configurable_Run_Time_On_Target
       then
          WBI ("   type No_Param_Proc is access procedure;");
+         WBI ("   pragma Favor_Top_Level (No_Param_Proc);");
          WBI ("");
       end if;
 

gcc/ada/exp_ch4.adb

@@ -8221,6 +8221,32 @@ package body Exp_Ch4 is
             Insert_Actions      (N, Bodies,           Suppress => All_Checks);
             Analyze_And_Resolve (N, Standard_Boolean, Suppress => All_Checks);
          end if;
+
+      --  If unnesting, handle elementary types whose Equivalent_Types are
+      --  records because there may be padding or undefined fields.
+
+      elsif Unnest_Subprogram_Mode
+        and then Ekind_In (Typl, E_Class_Wide_Type,
+                                 E_Class_Wide_Subtype,
+                                 E_Access_Subprogram_Type,
+                                 E_Access_Protected_Subprogram_Type,
+                                 E_Anonymous_Access_Protected_Subprogram_Type,
+                                 E_Access_Subprogram_Type,
+                                 E_Exception_Type)
+        and then Present (Equivalent_Type (Typl))
+        and then Is_Record_Type (Equivalent_Type (Typl))
+      then
+         Typl := Equivalent_Type (Typl);
+         Remove_Side_Effects (Lhs);
+         Remove_Side_Effects (Rhs);
+         Rewrite (N,
+           Expand_Record_Equality (N, Typl,
+             Unchecked_Convert_To (Typl, Lhs),
+             Unchecked_Convert_To (Typl, Rhs),
+             Bodies));
+
+         Insert_Actions      (N, Bodies,           Suppress => All_Checks);
+         Analyze_And_Resolve (N, Standard_Boolean, Suppress => All_Checks);
       end if;
 
       --  Test if result is known at compile time
@@ -9497,10 +9523,21 @@ package body Exp_Ch4 is
       Typ : constant Entity_Id := Etype (Left_Opnd (N));
 
    begin
-      --  Case of elementary type with standard operator
+      --  Case of elementary type with standard operator.  But if
+      --  unnesting, handle elementary types whose Equivalent_Types are
+      --  records because there may be padding or undefined fields.
 
       if Is_Elementary_Type (Typ)
         and then Sloc (Entity (N)) = Standard_Location
+        and then not (Ekind_In (Typ, E_Class_Wide_Type,
+                                E_Class_Wide_Subtype,
+                                E_Access_Subprogram_Type,
+                                E_Access_Protected_Subprogram_Type,
+                                E_Anonymous_Access_Protected_Subprogram_Type,
+                                E_Access_Subprogram_Type,
+                                E_Exception_Type)
+                        and then Present (Equivalent_Type (Typ))
+                        and then Is_Record_Type (Equivalent_Type (Typ)))
       then
          Binary_Op_Validity_Checks (N);
 

gcc/ada/libgnarl/s-interr.adb

@@ -545,9 +545,11 @@ package body System.Interrupts is
 
    function Is_Registered (Handler : Parameterless_Handler) return Boolean is
 
+      type Acc_Proc is access procedure;
+
       type Fat_Ptr is record
          Object_Addr  : System.Address;
-         Handler_Addr : System.Address;
+         Handler_Addr : Acc_Proc;
       end record;
 
       function To_Fat_Ptr is new Ada.Unchecked_Conversion
@@ -565,7 +567,7 @@ package body System.Interrupts is
 
       Ptr := Registered_Handler_Head;
       while Ptr /= null loop
-         if Ptr.H = Fat.Handler_Addr then
+         if Ptr.H = Fat.Handler_Addr.all'Address then
             return True;
          end if;
 

gcc/ada/libgnarl/s-interr__hwint.adb

@@ -561,9 +561,12 @@ package body System.Interrupts is
    -------------------
 
    function Is_Registered (Handler : Parameterless_Handler) return Boolean is
+
+      type Acc_Proc is access procedure;
+
       type Fat_Ptr is record
          Object_Addr  : System.Address;
-         Handler_Addr : System.Address;
+         Handler_Addr : Acc_Proc;
       end record;
 
       function To_Fat_Ptr is new Ada.Unchecked_Conversion
@@ -581,7 +584,7 @@ package body System.Interrupts is
 
       Ptr := Registered_Handler_Head;
       while Ptr /= null loop
-         if Ptr.H = Fat.Handler_Addr then
+         if Ptr.H = Fat.Handler_Addr.all'Address then
             return True;
          end if;
 

gcc/ada/libgnarl/s-interr__sigaction.adb

@@ -487,9 +487,11 @@ package body System.Interrupts is
    function Is_Registered (Handler : Parameterless_Handler) return Boolean is
       Ptr : R_Link := Registered_Handlers;
 
+      type Acc_Proc is access procedure;
+
       type Fat_Ptr is record
          Object_Addr  : System.Address;
-         Handler_Addr : System.Address;
+         Handler_Addr : Acc_Proc;
       end record;
 
       function To_Fat_Ptr is new Ada.Unchecked_Conversion
@@ -505,7 +507,7 @@ package body System.Interrupts is
       Fat := To_Fat_Ptr (Handler);
 
       while Ptr /= null loop
-         if Ptr.H = Fat.Handler_Addr then
+         if Ptr.H = Fat.Handler_Addr.all'Address then
             return True;
          end if;
 

gcc/ada/libgnarl/s-interr__vxworks.adb

@@ -578,9 +578,12 @@ package body System.Interrupts is
    -------------------
 
    function Is_Registered (Handler : Parameterless_Handler) return Boolean is
+
+      type Acc_Proc is access procedure;
+
       type Fat_Ptr is record
          Object_Addr  : System.Address;
-         Handler_Addr : System.Address;
+         Handler_Addr : Acc_Proc;
       end record;
 
       function To_Fat_Ptr is new Ada.Unchecked_Conversion
@@ -598,7 +601,7 @@ package body System.Interrupts is
 
       Ptr := Registered_Handler_Head;
       while Ptr /= null loop
-         if Ptr.H = Fat.Handler_Addr then
+         if Ptr.H = Fat.Handler_Addr.all'Address then
             return True;
          end if;