From: Eric Botcazou <ebotca...@adacore.com> 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