[PATCH] Code coverage mapping generation that enables coverage using the instrumentation based profiling

[Alex L]

The 'CoverageSourceInfo' class that stores the skipped ranges is not a good
approach because when the llvm codegenerator is created the preprocessing
record doesn't actually have the skipped ranges as they aren't reached by
the lexer yet.
What about this: the 'CoverageSourceInfo' derives from PPCallbacks and
stores it's own source ranges instead of relying on the preprocessing
record. I think that this might be an even better approach as
lib/Frontend/CompilerInstance.cpp wouldn't have to be modified.
Alex


2014-07-18 12:06 GMT-07:00 Alex L <arphaman at gmail.com>:

>
>
>
> 2014-07-18 11:47 GMT-07:00 Argyrios Kyrtzidis <kyrtzidis at apple.com>:
>
>
>> On Jul 18, 2014, at 9:56 AM, Sean Silva <chisophugis at gmail.com> wrote:
>>
>>
>>
>>
>> On Thu, Jul 17, 2014 at 2:14 PM, Bob Wilson <bob.wilson at apple.com> wrote:
>>
>>>
>>> > On Jul 8, 2014, at 10:43 AM, Alex L <arphaman at gmail.com> wrote:
>>> >
>>> > Hi everyone,
>>> >
>>> > I've attached a patch with the initial implementation of the code
>>> coverage mapping generation that
>>> > enables code coverage analysis which uses the data obtained from the
>>> instrumentation based profiling.
>>> >
>>> > I've sent out the patches for the coverage mapping format library and
>>> the updated coverage tool in separate threads.
>>> >
>>> > Cheers,
>>> > Alex
>>> > <clangCoverageMapping.patch>
>>>
>>> This looks really nice! It is obviously blocked by getting the llvm
>>> changes in, but it is otherwise mostly ready to commit. I just have a few
>>> small comments.
>>>
>>> It is unfortunate that you have to propagate the Preprocessor through a
>>> bunch of code to make it available in CodeGen. I can’t think of any good
>>> alternative, though. It would be good to get someone more familiar with the
>>> overall structure of the front-end to review that part.
>>>
>>
>> Agreed. That seems sort of funky. Does the code use anything other than
>> the PreprocessingRecord? Could we just pass that down instead of the full
>> Preprocessor?
>>
>>
>> Looks like only SkippedRanges are used from the PreprocessingRecord.
>> Could we have something like ‘CoverageSourceInfo’ class containing the
>> SkippedRanges (and anything else useful) and thread this through to CodeGen
>> ?
>>
>>
> Yes, only the SkippedRanges are used. A separate class like
> 'CoverageSourceInfo' sounds like a good idea, I will pass it instead of the
> preprocesor to CodeGen.
>
>>
>> Notwithstanding my suggestion, someone with better knowledge of the
>> layering here should sign off before this gets committed.
>>
>> -- Sean Silva
>>
>>
>>>
>>> I also noticed that you are adding a number of functions that don’t
>>> follow the naming convention of starting with a lowercase letter. I know
>>> there is a lot of code in clang that doesn’t follow that convention, and
>>> perhaps you are doing it that way on purpose to be consistent, but please
>>> review all the new function names and follow the coding standard, except
>>> for any cases where it clearly makes more sense to match the existing code.
>>>
>>> > @@ -807,6 +848,17 @@ static void emitRuntimeHook(CodeGenModule &CGM) {
>>> >    CGM.addUsedGlobal(User);
>>> >  }
>>> >
>>> > +void CodeGenPGO::checkGlobalDecl(GlobalDecl GD) {
>>> > +  // Make sure we only emit coverage mapping for one
>>> > +  // constructor/destructor
>>>
>>> Please elaborate on this comment to explain why it is an issue.
>>>
>>> > +  if ((isa<CXXConstructorDecl>(GD.getDecl()) &&
>>> > +       GD.getCtorType() != Ctor_Base) ||
>>> > +      (isa<CXXDestructorDecl>(GD.getDecl()) &&
>>> > +       GD.getDtorType() != Dtor_Base)) {
>>> > +    SkipCoverageMapping = true;
>>> > +  }
>>> > +}
>>> > +
>>> >  void CodeGenPGO::assignRegionCounters(const Decl *D, llvm::Function
>>> *Fn) {
>>> >    bool InstrumentRegions = CGM.getCodeGenOpts().ProfileInstrGenerate;
>>> >    llvm::IndexedInstrProfReader *PGOReader = CGM.getPGOReader();
>>>
>>> …
>>>
>>> > diff --git a/lib/CodeGen/CoverageMappingGen.cpp
>>> b/lib/CodeGen/CoverageMappingGen.cpp
>>> > new file mode 100644
>>> > index 0000000..ed65660
>>> > --- /dev/null
>>> > +++ b/lib/CodeGen/CoverageMappingGen.cpp
>>> > @@ -0,0 +1,1178 @@
>>> > +//===--- CoverageMappingGen.cpp - Coverage mapping generation ---*-
>>> C++ -*-===//
>>> > +//
>>> > +//                     The LLVM Compiler Infrastructure
>>> > +//
>>> > +// This file is distributed under the University of Illinois Open
>>> Source
>>> > +// License. See LICENSE.TXT for details.
>>> > +//
>>> >
>>> +//===----------------------------------------------------------------------===//
>>> > +//
>>> > +// Instrumentation-based code coverage mapping generator
>>> > +//
>>> >
>>> +//===----------------------------------------------------------------------===//
>>> > +
>>> > +#include "CoverageMappingGen.h"
>>> > +#include "CodeGenFunction.h"
>>> > +#include "clang/AST/RecursiveASTVisitor.h”
>>>
>>> I don’t see any direct use of RecursiveASTVisitor in this file. Is this
>>> #include really needed?
>>>
>>> …
>>>
>>> > +/// \brief A StmtVisitor that creates unreachable coverage regions
>>> for the
>>> > +/// functions that are not emitted.
>>> > +struct EmptyCoverageMappingBuilder : public CoverageMappingBuilder {
>>>
>>> The comment is wrong — this is not actually a StmtVisitor.
>>>
>>> …
>>>
>>> > +/// \brief A StmtVisitor that creates coverage mapping regions maps
>>> the
>>> > +/// source code locations to PGO counters.
>>> > +struct CounterCoverageMappingBuilder
>>> > +    : public CoverageMappingBuilder,
>>> > +      public ConstStmtVisitor<CounterCoverageMappingBuilder> {
>>>
>>> The comment here isn’t a proper sentence. Maybe you intended “maps” to
>>> be “that map”?
>>>
>>> The rest of this patch looks really good to me.
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>>
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