These checks are not very costly these days and bring additional safety
and security guarantees built into the Ada language, so enable them by
default.
It turns out that enabling checks on s-bitfie.adb makes a latent
visibility bug appeared on strict alignment platform (related to
alignment checks most likely). Workaround it for the time being by
suppressing checks locally.
It also makes visible a latent issue with secondary stack allocation of
0 bytes, now possible with another recent change to allocate the result
of string concatenation sometimes on the secondary stack.
Tested on x86_64-pc-linux-gnu, committed on trunk
gcc/ada/
* gcc-interface/Makefile.in (GNATLIBFLAGS): Enable checks by
default.
* libgnat/s-bitfie.ads: Suppress alignment checks.
* libgnat/s-bituti.adb: Minor reformatting.
* libgnat/s-secsta.adb (SS_Allocate): Support Size = 0.diff --git a/gcc/ada/gcc-interface/Makefile.in b/gcc/ada/gcc-interface/Makefile.in
--- a/gcc/ada/gcc-interface/Makefile.in
+++ b/gcc/ada/gcc-interface/Makefile.in
@@ -110,7 +110,7 @@ NO_INLINE_ADAFLAGS = -fno-inline
NO_OMIT_ADAFLAGS = -fno-omit-frame-pointer
NO_SIBLING_ADAFLAGS = -fno-optimize-sibling-calls
NO_REORDER_ADAFLAGS = -fno-toplevel-reorder
-GNATLIBFLAGS = -W -Wall -gnatpg -nostdinc
+GNATLIBFLAGS = -W -Wall -gnatg -nostdinc
GNATLIBCFLAGS = -g -O2
# Pretend that _Unwind_GetIPInfo is available for the target by default. This
# should be autodetected during the configuration of libada and passed down to
diff --git a/gcc/ada/libgnat/s-bitfie.ads b/gcc/ada/libgnat/s-bitfie.ads
--- a/gcc/ada/libgnat/s-bitfie.ads
+++ b/gcc/ada/libgnat/s-bitfie.ads
@@ -47,6 +47,12 @@ package System.Bitfields is
pragma Provide_Shift_Operators (Val_2);
type Val is mod 2**Val_Bits with Alignment => Val_Bytes;
+ -- ??? It turns out that enabling checks on the instantiation of
+ -- System.Bitfield_Utils.G makes a latent visibility bug appear on strict
+ -- alignment platforms related to alignment checks. Work around it by
+ -- suppressing these checks explicitly.
+
+ pragma Suppress (Alignment_Check);
package Utils is new System.Bitfield_Utils.G (Val, Val_2);
procedure Copy_Bitfield
diff --git a/gcc/ada/libgnat/s-bituti.adb b/gcc/ada/libgnat/s-bituti.adb
--- a/gcc/ada/libgnat/s-bituti.adb
+++ b/gcc/ada/libgnat/s-bituti.adb
@@ -317,6 +317,7 @@ package body System.Bitfield_Utils is
Get_Val_2 (S_Addr, S_Off, Initial_Size);
Initial_Val : constant Val :=
Get_Bitfield (Initial_Val_2, S_Off, Initial_Size);
+
begin
Set_Bitfield
(Initial_Val, D_Addr, D_Off, Initial_Size);
diff --git a/gcc/ada/libgnat/s-secsta.adb b/gcc/ada/libgnat/s-secsta.adb
--- a/gcc/ada/libgnat/s-secsta.adb
+++ b/gcc/ada/libgnat/s-secsta.adb
@@ -587,15 +587,18 @@ package body System.Secondary_Stack is
-- Start of processing for SS_Allocate
begin
- -- It should not be possible to request an allocation of negative or
- -- zero size.
-
- pragma Assert (Storage_Size > 0);
-
-- Round the requested size up to the nearest multiple of the maximum
-- alignment to ensure efficient access.
- Mem_Size := Round_Up (Storage_Size);
+ if Storage_Size = 0 then
+ Mem_Size := Memory_Alignment;
+ else
+ -- It should not be possible to request an allocation of negative
+ -- size.
+
+ pragma Assert (Storage_Size >= 0);
+ Mem_Size := Round_Up (Storage_Size);
+ end if;
if Sec_Stack_Dynamic then
Allocate_Dynamic (Stack, Mem_Size, Addr);
