A new aspect/pragma can be attached to volatile variables to indicate that such a variable is not used for interactions with the external world, but only that accesses to that variable should not be optimized by the compiler. This is in particular useful for guarding against fault injection. SPARK Reference manual has been updated to allow this use of volatile data, see section 7.1.2, so that GNATprove can analyze such variables as not volatile.
Tested on x86_64-pc-linux-gnu, committed on trunk
2019-08-12 Yannick Moy <m...@adacore.com>
gcc/ada/
* aspects.adb, aspects.ads (Aspect_No_Caching): New aspect.
* contracts.adb, contracts.ads (Add_Contract_Item): Add handling
of No_Caching.
(Analyze_Object_Contract): Add handling of No_Caching.
* einfo.adb, einfo.ads
(Get_Pragma): Add handling of No_Caching.
* doc/gnat_rm/implementation_defined_aspects.rst,
doc/gnat_rm/implementation_defined_pragmas.rst: Document new
aspect/pragma.
* gnat_rm.texi: Regenerate.
* par-prag.adb (Prag): New pragma Pragma_No_Caching.
* sem_ch13.adb (Analyze_Aspect_Specifications,
Check_Aspect_At_Freeze_Point): Add handling of No_Caching.
* sem_prag.adb (Analyze_Pragma): Deal with pragma No_Caching.
* sem_prag.ads (Analyze_External_Property_In_Decl_Part): Now
applies to No_Caching.
* sem_util.adb, sem_util.ads (Is_Effectively_Volatile): Add
handling of No_Caching.
(No_Caching_Enabled): New query function.
* snames.ads-tmpl: New names for pragma.
gcc/testsuite/
* gnat.dg/no_caching.adb, gnat.dg/no_caching.ads: New testcase.
patch.diff.gz
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