This change fixes a long-standing issue in the compiler that is
generally silent but may lead to wrong code generation in specific
circumstances. When an others choice in an array aggregate spans
multiple ranges, the compiler may generate multiple (groups of)
assignments for the ranges.
The problem is that it internally reuses the original expression for all
the ranges, which is problematic if this expression gets rewritten
during the processing of one of the ranges and typically causes a new
temporary to be shared between different ranges.
The solution is to duplicate the original expression for each range.
Tested on x86_64-pc-linux-gnu, committed on trunk
2019-09-18 Eric Botcazou <ebotca...@adacore.com>
gcc/ada/
* exp_aggr.adb (Build_Array_Aggr_Code): In STEP 1 (c), duplicate
the expression and reset the Loop_Actions for each loop
generated for an others choice.
gcc/testsuite/
* gnat.dg/aggr28.adb: New testcase.--- gcc/ada/exp_aggr.adb
+++ gcc/ada/exp_aggr.adb
@@ -2075,7 +2075,6 @@ package body Exp_Aggr is
Choice := First (Choice_List (Assoc));
while Present (Choice) loop
if Nkind (Choice) = N_Others_Choice then
- Set_Loop_Actions (Assoc, New_List);
Others_Assoc := Assoc;
exit;
end if;
@@ -2122,7 +2121,8 @@ package body Exp_Aggr is
if Present (Others_Assoc) then
declare
- First : Boolean := True;
+ First : Boolean := True;
+ Dup_Expr : Node_Id;
begin
for J in 0 .. Nb_Choices loop
@@ -2160,9 +2160,19 @@ package body Exp_Aggr is
or else not Empty_Range (Low, High)
then
First := False;
+
+ -- Duplicate the expression in case we will be generating
+ -- several loops. As a result the expression is no longer
+ -- shared between the loops and is reevaluated for each
+ -- such loop.
+
+ Expr := Get_Assoc_Expr (Others_Assoc);
+ Dup_Expr := New_Copy_Tree (Expr);
+ Set_Parent (Dup_Expr, Parent (Expr));
+
+ Set_Loop_Actions (Others_Assoc, New_List);
Append_List
- (Gen_Loop (Low, High,
- Get_Assoc_Expr (Others_Assoc)), To => New_Code);
+ (Gen_Loop (Low, High, Dup_Expr), To => New_Code);
end if;
end loop;
end;
--- /dev/null
new file mode 100644
+++ gcc/testsuite/gnat.dg/aggr28.adb
@@ -0,0 +1,29 @@
+-- { dg-do run }
+
+procedure Aggr28 is
+
+ Count : Natural := 0;
+
+ function Get (S: String) return String is
+ begin
+ Count := Count + 1;
+ return S;
+ end;
+
+ Max_Error_Length : constant := 8;
+ subtype Error_Type is String (1 .. Max_Error_Length);
+
+ type Rec is record
+ Text : Error_Type;
+ end record;
+
+ type Arr is array (1 .. 16) of Rec;
+
+ Table : constant Arr :=
+ (3 => (Text => Get ("INVALID ")), others => (Text => Get ("OTHERS ")));
+
+begin
+ if Count /= Table'Length then
+ raise Program_Error;
+ end if;
+end;
\ No newline at end of file
