From: Bob Duff <d...@adacore.com>
This patch disables the Fast_Copy_Bitfield optimization in certain rare
cases that currently do not work (crash in gigi). We could improve
Expand_Assign_Array_Bitfield_Fast to handle these cases properly, but
that change is delicate, so for now, we simply disable the optimization.
gcc/ada/
* exp_ch5.adb
(Expand_Assign_Array_Loop_Or_Bitfield): Disable the
Fast_Copy_Bitfield optimization in certain cases.
Tested on x86_64-pc-linux-gnu, committed on master.
---
gcc/ada/exp_ch5.adb | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/gcc/ada/exp_ch5.adb b/gcc/ada/exp_ch5.adb
index 209741c82cf..9669737a79b 100644
--- a/gcc/ada/exp_ch5.adb
+++ b/gcc/ada/exp_ch5.adb
@@ -1660,6 +1660,15 @@ package body Exp_Ch5 is
return False;
end Volatile_Or_Independent;
+ function Slice_Of_Packed_Component (L : Node_Id) return Boolean is
+ (Nkind (L) = N_Slice
+ and then Nkind (Prefix (L)) = N_Indexed_Component
+ and then Is_Bit_Packed_Array (Etype (Prefix (Prefix (L)))));
+ -- L is the left-hand side Name. Returns True if L is a slice of a
+ -- component of a bit-packed array. The optimization is disabled in
+ -- that case, because Expand_Assign_Array_Bitfield_Fast cannot
+ -- currently handle that case correctly.
+
L : constant Node_Id := Name (N);
R : constant Node_Id := Expression (N);
-- Left- and right-hand sides of the assignment statement
@@ -1681,6 +1690,7 @@ package body Exp_Ch5 is
and then not Reverse_Storage_Order (R_Type)
and then Ndim = 1
and then Slices
+ and then not Slice_Of_Packed_Component (L)
and then not Volatile_Or_Independent (L, L_Type)
and then not Volatile_Or_Independent (R, R_Type)
then
--
2.34.1
