From: Eric Botcazou <[email protected]>
The partial solution implemented in Validate_Unchecked_Conversion to support
unchecked conversions between addresses and pointers to subprograms, for the
platforms where pointers to subprograms do not all have the same size, turns
out to be counter-productive for others because it may cause the creation of
useless trampolines, which in turn makes the stack executable.
gcc/ada/
* sem_ch13.adb (Validate_Unchecked_Conversion): Restrict forcing the
Can_Use_Internal_Rep flag to platforms that require unnesting.
Tested on x86_64-pc-linux-gnu, committed on master.
---
gcc/ada/sem_ch13.adb | 29 ++++++++++++++++-------------
1 file changed, 16 insertions(+), 13 deletions(-)
diff --git a/gcc/ada/sem_ch13.adb b/gcc/ada/sem_ch13.adb
index 59c80022c20..4cf6fc9a645 100644
--- a/gcc/ada/sem_ch13.adb
+++ b/gcc/ada/sem_ch13.adb
@@ -18132,20 +18132,23 @@ package body Sem_Ch13 is
Set_No_Strict_Aliasing (Implementation_Base_Type (Target));
end if;
- -- If the unchecked conversion is between Address and an access
- -- subprogram type, show that we shouldn't use an internal
- -- representation for the access subprogram type.
+ -- For code generators that do not support nested subprograms, if the
+ -- unchecked conversion is between Address and an access subprogram
+ -- type, show that we shouldn't use an internal representation for the
+ -- access subprogram type.
- if Is_Access_Subprogram_Type (Target)
- and then Is_Descendant_Of_Address (Source)
- and then In_Same_Source_Unit (Target, N)
- then
- Set_Can_Use_Internal_Rep (Base_Type (Target), False);
- elsif Is_Access_Subprogram_Type (Source)
- and then Is_Descendant_Of_Address (Target)
- and then In_Same_Source_Unit (Source, N)
- then
- Set_Can_Use_Internal_Rep (Base_Type (Source), False);
+ if Unnest_Subprogram_Mode then
+ if Is_Access_Subprogram_Type (Target)
+ and then Is_Descendant_Of_Address (Source)
+ and then In_Same_Source_Unit (Target, N)
+ then
+ Set_Can_Use_Internal_Rep (Base_Type (Target), False);
+ elsif Is_Access_Subprogram_Type (Source)
+ and then Is_Descendant_Of_Address (Target)
+ and then In_Same_Source_Unit (Source, N)
+ then
+ Set_Can_Use_Internal_Rep (Base_Type (Source), False);
+ end if;
end if;
-- Generate N_Validate_Unchecked_Conversion node for back end in case
--
2.43.2
