[cfe-commits] [PATCH] Add three new sanitizers depending on ASan.

[Alexey Samsonov]

On Wed, Nov 28, 2012 at 3:22 AM, Kostya Serebryany <kcc at google.com> wrote:

>
>
> On Wed, Nov 28, 2012 at 10:28 AM, Alexey Samsonov <samsonov at google.com>wrote:
>
>>
>>   Ok. Kostya, what is your opinion?
>>
>
> On which part? I like the flags.
>

Ok.


> As for "-mllvm -asan-foo" vs createAddressSanitizerPass flags I have mixed
> feelings.
> If we use createAddressSanitizerPass flags, what should be the behavior
> when "-mllvm -asan-foo" is given separately?
>

I think that explicit -mllvm -asan-use-after-return=0 should override
"-fsanitize=use-after-return" option (questionable).
Anyway, I think we should discourage users to use -mllvm flags. BTW, if we
will add "-mllvm -asan-use-after-return" flag in
clang Driver, then the line "-fsanitize=use-after-return -mllvm
-asan-use-after-return=1" will produce a compiler error, stating that
"-asan-use-after-return" option can be present 0 or 1 times. So, I think
that we should follow Richard's suggestion.


> What are other phases doing in similar situations (or we are doing
> something unique)?
>

GCOV profiler added in clang's BackendUtil is configured from CodeGenOpts:
if (CodeGenOpts.EmitGcovArcs || CodeGenOpts.EmitGcovNotes) {
  MPM->add(createGCOVProfilerPass(CodeGenOpts.EmitGcovNotes,
CodeGenOpts.EmitGcovArcs, TargetTriple.isMacOSX()));
with the declaration:
  ModulePass *createGCOVProfilerPass(bool EmitNotes = true, bool EmitData =
true, bool Use402Format = false, bool UseExtraChecksum = false);

We may do smth similar for ASan.


>
>

>
> --kcc
>
>
>>
>> ================
>> Comment at: lib/Driver/Tools.cpp:1518-1523
>> @@ -1517,1 +1517,8 @@
>> +
>> +  // If -fsanitize contains extra features of ASan, it should also
>> +  // explicitly contain -fsanitize=address.
>> +  if (NeedsAsan && ((Kind & Address) == 0))
>> +    D.Diag(diag::err_drv_argument_only_allowed_with)
>> +      << describeSanitizeArg(Args, AsanArg, NeedsAsanRt)
>> +      << "-fsanitize=address";
>>  }
>> ----------------
>> Richard Smith wrote:
>> > For argument lists like "-fsanitize=use-after-return -fsanitize=address
>> -fno-sanitize=address", we'll say "-fsanitize=address is only allowed with
>> -fsanitize=address". The existing diagnostic has a similar issue for
>> "-fsanitize=address -fsanitize=alignment -fsanitize=vptr
>> -fno-sanitize=vptr", where it says "-fsanitize=vptr not allowed with
>> -fsanitize=address". I think we'd need to teach describeSanitizerArg to
>> re-parse the argument list to handle this properly.
>> RIght, the logic is untrivial here. Mailed D143 to fix this.
>>
>> ================
>> Comment at: lib/Driver/SanitizerArgs.h:59-71
>> @@ -58,1 +58,15 @@
>> +
>> +    // Add args for LLVM backend.
>> +    if (Kind & InitOrder) {
>> +      CmdArgs.push_back("-mllvm");
>> +      CmdArgs.push_back("-asan-initialization-order");
>> +    }
>> +    if (Kind & UseAfterReturn) {
>> +      CmdArgs.push_back("-mllvm");
>> +      CmdArgs.push_back("-asan-use-after-return");
>> +    }
>> +    if (Kind & UseAfterScope) {
>> +      CmdArgs.push_back("-mllvm");
>> +      CmdArgs.push_back("-asan-use-lifetime");
>> +    }
>>    }
>> ----------------
>> Richard Smith wrote:
>> > I would prefer this to be handled by the frontend instead of by the
>> driver (the frontend is responsible for adding all the other IR
>> instrumentation, including adding the ASan passes).
>> >
>> > Have you considered passing these flags to ASan when creating the
>> passes in addAddressSanitizerPass, rather than as command-line options?
>> Hm, passing arguments to createAddressSanitizerPass() certainly seems a
>> better (though, more intrusive) solution than playing with -mllvm flags.
>> I'll work on that.
>>
>>
>> http://llvm-reviews.chandlerc.com/D142
>>
>
>


-- 
Alexey Samsonov, MSK
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