Pragma Component_Alignment was not implemented properly and caused a crash
when used in a configuration file due to how it was applied via the scope
table. This patch correctly identifies this case and uses a global variable
Configuration_Component_Alignment to capture the value set during
configuration analysis and applies it in place of the default value.
------------
-- Source --
------------
-- stor_unit.adc
pragma Component_Alignment (Form => Storage_Unit);
-- pack_storage_unit.ads
package Pack_Storage_Unit is
pragma Component_Alignment (Form => Storage_Unit);
type Small_Int is new Integer range 0 .. 1;
for Small_Int'Size use 1;
type Rec is record
Comp_1 : Small_Int;
Comp_2 : Small_Int;
Comp_3 : Boolean;
Comp_4 : Integer;
Comp_5 : Long_Integer;
end record;
end Pack_Storage_Unit;
-- pack.ads
package Pack is
type Small_Int is new Integer range 0 .. 1;
for Small_Int'Size use 1;
type Rec is record
Comp_1 : Small_Int;
Comp_2 : Small_Int;
Comp_3 : Boolean;
Comp_4 : Integer;
Comp_5 : Long_Integer;
end record;
end Pack;
----------------------------
-- Compilation and output --
----------------------------
$ gcc -c -gnatR pack_storage_unit.ads > output1.txt
$ gcc -c -gnatR pack.ads -gnatec=stor_unit.adc > output2.txt
$ grep -v -F -x -f output1.txt output2.txt
Representation information for unit Pack (spec)
for Rec'Size use 128;
for Rec'Alignment use 8;
Comp_4 at 4 range 0 .. 31;
Comp_5 at 8 range 0 .. 63;
Tested on x86_64-pc-linux-gnu, committed on trunk
2016-06-22 Justin Squirek <squi...@adacore.com>
* sem_ch8.adb (Push_Scope): Add a check for when the
scope table is empty to assign the global variable
Configuration_Component_Alignment.
* sem.adb (Do_Analyze): Add Configuration_Component_Alignment
to be assigned when the environment is cleaned instead of the
default.
* sem.ads Add a global variable Configuration_Component_Alignment
to store the value given by pragma Component_Alignment in the
context of a configuration file.
* sem_prag.adb (Analyze_Pragma): Correct the case for
Component_Alignment so that the pragma is verified and add
comments to explain how it is applied to the scope stack.
Index: sem.adb
===================================================================
--- sem.adb (revision 237680)
+++ sem.adb (working copy)
@@ -1355,7 +1355,8 @@
Outer_Generic_Scope := Empty;
Scope_Suppress := Suppress_Options;
Scope_Stack.Table
- (Scope_Stack.Last).Component_Alignment_Default := Calign_Default;
+ (Scope_Stack.Last).Component_Alignment_Default :=
+ Configuration_Component_Alignment;
Scope_Stack.Table
(Scope_Stack.Last).Is_Active_Stack_Base := True;
Index: sem.ads
===================================================================
--- sem.ads (revision 237680)
+++ sem.ads (working copy)
@@ -461,6 +461,11 @@
-- Transient blocks have three associated actions list, to be inserted
-- before and after the block's statements, and as cleanup actions.
+ Configuration_Component_Alignment : Component_Alignment_Kind :=
+ Calign_Default;
+ -- Used for handling the pragma Component_Alignment in the context of a
+ -- configuration file.
+
type Scope_Stack_Entry is record
Entity : Entity_Id;
-- Entity representing the scope
Index: sem_ch8.adb
===================================================================
--- sem_ch8.adb (revision 237693)
+++ sem_ch8.adb (working copy)
@@ -8192,10 +8192,22 @@
SST.Save_Default_SSO := Default_SSO;
SST.Save_Uneval_Old := Uneval_Old;
+ -- Each new scope pushed onto the scope stack inherits the component
+ -- alignment of the previous scope. This emulates the "visibility"
+ -- semantics of pragma Component_Alignment.
+
if Scope_Stack.Last > Scope_Stack.First then
SST.Component_Alignment_Default := Scope_Stack.Table
(Scope_Stack.Last - 1).
Component_Alignment_Default;
+
+ -- Otherwise, this is the first scope being pushed on the scope
+ -- stack. Inherit the component alignment from the configuration
+ -- form of pragma Component_Alignment (if any).
+
+ else
+ SST.Component_Alignment_Default :=
+ Configuration_Component_Alignment;
end if;
SST.Last_Subprogram_Name := null;
Index: sem_prag.adb
===================================================================
--- sem_prag.adb (revision 237693)
+++ sem_prag.adb (working copy)
@@ -12787,9 +12787,21 @@
("invalid Form parameter for pragma%", Form);
end if;
+ -- The pragma appears in a configuration file
+
+ if No (Parent (N)) then
+ Check_Valid_Configuration_Pragma;
+
+ -- Capture the component alignment in a global variable when
+ -- the pragma appears in a configuration file. Note that the
+ -- scope stack is empty at this point and cannot be used to
+ -- store the alignment value.
+
+ Configuration_Component_Alignment := Atype;
+
-- Case with no name, supplied, affects scope table entry
- if No (Name) then
+ elsif No (Name) then
Scope_Stack.Table
(Scope_Stack.Last).Component_Alignment_Default := Atype;
@@ -20901,7 +20913,7 @@
Mode_Id := Get_SPARK_Mode_Type (Mode);
Context := Parent (N);
- -- The pragma appears in a configuration pragmas file
+ -- The pragma appears in a configuration file
if No (Context) then
Check_Valid_Configuration_Pragma;
