[RFC]: Fix Ada boostrap failure on S/390 with -mzarch

[Andreas Krebbel]

On 04/03/2017 06:18 PM, Eric Botcazou wrote:
>> On S/390 UNITS_PER_WORD is:
>> 8 with -m64
>> 4 with -m31
>> 8 with -m31 -mzarch
>>
>> This has been chosen to support use of 64 bit registers also in 32 bit
>> code.  Code compiled with -m31 -mzarch is supposed to adhere to the 32
>> bit ABI.  In order to make that work it was required to prevent
>> UNITS_PER_WORD from being used in ABI-relevant contexts.  That's why
>> Ulrich added the TARGET_UNWIND_WORD_MODE in 2008 (for SPU).
> 
> We do that for 32-bit SPARC on Solaris (-mv8plus) but UNITS_PER_WORD is 4.
> 
>> Now I could either fix this by reverting that change for S/390
>> (similiar to what Andreas Schwab did to fix the BZ) or I could just
>> use the size of the long data type (as we do in the ABI-relevant parts
>> of the backend as well).  Which one do you prefer?
> 
> Having System.Word_Size != Standard'Word_Size is a bit disturbing.  Does it 
> work to change only Memory_Size to 2 ** Long_Integer'Size?  This will also 
> correct the definition of Address below.

This worked as well. I've committed the following patch:

gcc/ada/ChangeLog:

2017-04-04  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* system-linux-s390.ads: Use Long_Integer'Size to define
	Memory_Size.
---
 gcc/ada/system-linux-s390.ads | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/ada/system-linux-s390.ads b/gcc/ada/system-linux-s390.ads
index 485a8de..9bf8375 100644
--- a/gcc/ada/system-linux-s390.ads
+++ b/gcc/ada/system-linux-s390.ads
@@ -70,7 +70,7 @@ package System is

    Storage_Unit : constant := 8;
    Word_Size    : constant := Standard'Word_Size;
-   Memory_Size  : constant := 2 ** Word_Size;
+   Memory_Size  : constant := 2 ** Long_Integer'Size;

    --  Address comparison