[llvm] r234963 - Change range-based for-loops to be -Wrange-loop-analysis clean.

Richard Trieu rtrieu at google.com
Wed Apr 15 11:39:42 PDT 2015


On Tue, Apr 14, 2015 at 9:36 PM, David Blaikie <dblaikie at gmail.com> wrote:

> On Tue, Apr 14, 2015 at 9:18 PM, Richard Trieu <rtrieu at google.com> wrote:
> >
> >
> > On Tue, Apr 14, 2015 at 8:28 PM, David Blaikie <dblaikie at gmail.com>
> wrote:
> >>
> >> On Tue, Apr 14, 2015 at 8:21 PM, Richard Trieu <rtrieu at google.com>
> wrote:
> >> > On Tue, Apr 14, 2015 at 6:33 PM, David Blaikie <dblaikie at gmail.com>
> >> > wrote:
> >> >>
> >> >> On Tue, Apr 14, 2015 at 6:21 PM, Richard Trieu <rtrieu at google.com>
> >> >> wrote:
> >> >> > Author: rtrieu
> >> >> > Date: Tue Apr 14 20:21:15 2015
> >> >> > New Revision: 234963
> >> >> >
> >> >> > URL: http://llvm.org/viewvc/llvm-project?rev=234963&view=rev
> >> >> > Log:
> >> >> > Change range-based for-loops to be -Wrange-loop-analysis clean.
> >> >> > No functionality change.
> >> >> >
> >> >> > Modified:
> >> >> >     llvm/trunk/lib/Analysis/RegionPass.cpp
> >> >> >     llvm/trunk/lib/CodeGen/WinEHPrepare.cpp
> >> >> >     llvm/trunk/lib/MC/MCDwarf.cpp
> >> >> >     llvm/trunk/lib/Object/COFFObjectFile.cpp
> >> >> >     llvm/trunk/lib/Target/AArch64/AArch64CollectLOH.cpp
> >> >> >     llvm/trunk/lib/Transforms/Scalar/StructurizeCFG.cpp
> >> >> >     llvm/trunk/tools/llvm-cxxdump/llvm-cxxdump.cpp
> >> >> >     llvm/trunk/utils/TableGen/CodeGenRegisters.cpp
> >> >> >
> >> >> > Modified: llvm/trunk/lib/Analysis/RegionPass.cpp
> >> >> > URL:
> >> >> >
> >> >> >
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/RegionPass.cpp?rev=234963&r1=234962&r2=234963&view=diff
> >> >> >
> >> >> >
> >> >> >
> ==============================================================================
> >> >> > --- llvm/trunk/lib/Analysis/RegionPass.cpp (original)
> >> >> > +++ llvm/trunk/lib/Analysis/RegionPass.cpp Tue Apr 14 20:21:15 2015
> >> >> > @@ -199,7 +199,7 @@ public:
> >> >> >
> >> >> >    bool runOnRegion(Region *R, RGPassManager &RGM) override {
> >> >> >      Out << Banner;
> >> >> > -    for (const auto &BB : R->blocks()) {
> >> >> > +    for (const auto *BB : R->blocks()) {
> >> >> >        if (BB)
> >> >> >          BB->print(Out);
> >> >> >        else
> >> >> >
> >> >> > Modified: llvm/trunk/lib/CodeGen/WinEHPrepare.cpp
> >> >> > URL:
> >> >> >
> >> >> >
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/WinEHPrepare.cpp?rev=234963&r1=234962&r2=234963&view=diff
> >> >> >
> >> >> >
> >> >> >
> ==============================================================================
> >> >> > --- llvm/trunk/lib/CodeGen/WinEHPrepare.cpp (original)
> >> >> > +++ llvm/trunk/lib/CodeGen/WinEHPrepare.cpp Tue Apr 14 20:21:15
> 2015
> >> >> > @@ -909,7 +909,7 @@ bool WinEHPrepare::outlineHandler(Action
> >> >> >      // save the association of the blocks in LPadTargetBlocks.
> The
> >> >> >      // return instructions which are created from these branches
> >> >> > will
> >> >> > be
> >> >> >      // replaced after all landing pads have been outlined.
> >> >> > -    for (const auto &MapEntry : VMap) {
> >> >> > +    for (const auto MapEntry : VMap) {
> >> >>
> >> >> What's the deal with this change? Is the type small & trivially
> >> >> copyable & we're suggesting using values instead of references?
> >> >>
> >> > VMap does not return a reference, so remove the reference type to
> >> > indicate a
> >> > copy is always made.
> >>
> >> Seems ValueMap uses a proxy (much like std::vector<bool>/bitset/etc).
> >>
> >> How much value do you think there is in warning when a reference is
> >> bound to a value return from operator*? I appreciate that it's useful
> >> when there's an intentional type difference (though that's tricky -
> >> are we warning there now? I forget) but if the types match it's sort
> >> of a benign reference, right?
> >>
> > I think it's mostly benign, as long as the container isn't changed and
> the
> > code expects the new value,
>
> Actually that's the trick - because these things are proxied, the code
> looks like it makes a copy of the container elements, but it actually
> doesn't:
>
> for (auto x : my_vec_bool_or_bitset)
>   x = 0;
>
> Does that code modify the container? Surprisingly, it does... - so I'm
> not sure it's helpful to remove the ref qualifier. While, yes,
> including the ref qualifier is a lie, I suspect it might be the lesser
> evil here... maybe. (granted you can use "const auto &x" and then
> write "x = 0;" and that will compile, and similarly be confusing to
> the author... so I'm not saying I have an iron-clad argument here)
>
> It looks like if there is "const auto &x" or "const auto x" for
vector<bool>, then "x = 0;" won't compile.  I wouldn't mind supporting
"const auto &x" for this case, but is there a way to detect these proxy
types?


> > or the reference is kept around after the loop.
> > However, this was the whole point of the warning, to divide up the syntax
> > for range-based for-loops so that every copy is done with a non-reference
> > type while every reference type will not bind to a temporary.
> Exceptions to
> > this rule just weaken the warning.
>
>
>
> >>
> >> >
> >> >>
> >> >> >        // VMap maps all values and blocks that were just cloned,
> but
> >> >> > dead
> >> >> >        // blocks which were pruned will map to nullptr.
> >> >> >        if (!isa<BasicBlock>(MapEntry.first) || MapEntry.second ==
> >> >> > nullptr)
> >> >> >
> >> >> > Modified: llvm/trunk/lib/MC/MCDwarf.cpp
> >> >> > URL:
> >> >> >
> >> >> >
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCDwarf.cpp?rev=234963&r1=234962&r2=234963&view=diff
> >> >> >
> >> >> >
> >> >> >
> ==============================================================================
> >> >> > --- llvm/trunk/lib/MC/MCDwarf.cpp (original)
> >> >> > +++ llvm/trunk/lib/MC/MCDwarf.cpp Tue Apr 14 20:21:15 2015
> >> >> > @@ -803,7 +803,7 @@ static void EmitGenDwarfRanges(MCStreame
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRangesSection());
> >> >> >
> >> >> > -  for (const auto sec : Sections) {
> >> >> > +  for (const auto &sec : Sections) {
> >> >> >
> >> >> >      MCSymbol *StartSymbol = sec.second.first;
> >> >> >      MCSymbol *EndSymbol = sec.second.second;
> >> >> >
> >> >> > Modified: llvm/trunk/lib/Object/COFFObjectFile.cpp
> >> >> > URL:
> >> >> >
> >> >> >
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Object/COFFObjectFile.cpp?rev=234963&r1=234962&r2=234963&view=diff
> >> >> >
> >> >> >
> >> >> >
> ==============================================================================
> >> >> > --- llvm/trunk/lib/Object/COFFObjectFile.cpp (original)
> >> >> > +++ llvm/trunk/lib/Object/COFFObjectFile.cpp Tue Apr 14 20:21:15
> 2015
> >> >> > @@ -262,7 +262,7 @@ std::error_code COFFObjectFile::getSymbo
> >> >> >    }
> >> >> >    const section_iterator SecEnd = section_end();
> >> >> >    uint64_t AfterAddr = UnknownAddressOrSize;
> >> >> > -  for (const symbol_iterator &SymbI : symbols()) {
> >> >> > +  for (const symbol_iterator SymbI : symbols()) {
> >> >>
> >> >> Drop const if we're dropping ref?
> >> >
> >> > See two lines above where the code uses a const iterator.  This change
> >> > follows the current code.
> >>
> >> Fair enough
> >>
> >> >>
> >> >>
> >> >> >      section_iterator SecI = SecEnd;
> >> >> >      if (std::error_code EC = SymbI->getSection(SecI))
> >> >> >        return EC;
> >> >> >
> >> >> > Modified: llvm/trunk/lib/Target/AArch64/AArch64CollectLOH.cpp
> >> >> > URL:
> >> >> >
> >> >> >
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64CollectLOH.cpp?rev=234963&r1=234962&r2=234963&view=diff
> >> >> >
> >> >> >
> >> >> >
> ==============================================================================
> >> >> > --- llvm/trunk/lib/Target/AArch64/AArch64CollectLOH.cpp (original)
> >> >> > +++ llvm/trunk/lib/Target/AArch64/AArch64CollectLOH.cpp Tue Apr 14
> >> >> > 20:21:15 2015
> >> >> > @@ -328,7 +328,7 @@ static void initReachingDef(const Machin
> >> >> >          const uint32_t *PreservedRegs = MO.getRegMask();
> >> >> >
> >> >> >          // Set generated regs.
> >> >> > -        for (const auto Entry : RegToId) {
> >> >> > +        for (const auto &Entry : RegToId) {
> >> >> >            unsigned Reg = Entry.second;
> >> >> >            // Use the global register ID when querying APIs
> external
> >> >> > to
> >> >> > this
> >> >> >            // pass.
> >> >> >
> >> >> > Modified: llvm/trunk/lib/Transforms/Scalar/StructurizeCFG.cpp
> >> >> > URL:
> >> >> >
> >> >> >
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/StructurizeCFG.cpp?rev=234963&r1=234962&r2=234963&view=diff
> >> >> >
> >> >> >
> >> >> >
> ==============================================================================
> >> >> > --- llvm/trunk/lib/Transforms/Scalar/StructurizeCFG.cpp (original)
> >> >> > +++ llvm/trunk/lib/Transforms/Scalar/StructurizeCFG.cpp Tue Apr 14
> >> >> > 20:21:15 2015
> >> >> > @@ -887,7 +887,7 @@ void StructurizeCFG::createFlow() {
> >> >> >  /// no longer dominate all their uses. Not sure if this is really
> >> >> > nessasary
> >> >> >  void StructurizeCFG::rebuildSSA() {
> >> >> >    SSAUpdater Updater;
> >> >> > -  for (const auto &BB : ParentRegion->blocks())
> >> >> > +  for (auto *BB : ParentRegion->blocks())
> >> >> >      for (BasicBlock::iterator II = BB->begin(), IE = BB->end();
> >> >> >           II != IE; ++II) {
> >> >> >
> >> >> >
> >> >> > Modified: llvm/trunk/tools/llvm-cxxdump/llvm-cxxdump.cpp
> >> >> > URL:
> >> >> >
> >> >> >
> http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-cxxdump/llvm-cxxdump.cpp?rev=234963&r1=234962&r2=234963&view=diff
> >> >> >
> >> >> >
> >> >> >
> ==============================================================================
> >> >> > --- llvm/trunk/tools/llvm-cxxdump/llvm-cxxdump.cpp (original)
> >> >> > +++ llvm/trunk/tools/llvm-cxxdump/llvm-cxxdump.cpp Tue Apr 14
> >> >> > 20:21:15
> >> >> > 2015
> >> >> > @@ -355,7 +355,8 @@ static void dumpCXXData(const ObjectFile
> >> >> >      StringRef SymName = VFTableEntry.second;
> >> >> >      outs() << VFTableName << '[' << Offset << "]: " << SymName <<
> >> >> > '\n';
> >> >> >    }
> >> >> > -  for (const std::pair<StringRef, ArrayRef<little32_t>> &VBTable :
> >> >> > VBTables) {
> >> >> > +  for (const std::pair<const StringRef, ArrayRef<little32_t>>
> >> >> > &VBTable
> >> >> > :
> >> >>
> >> >> Can probably use 'const auto &' here.
> >> >
> >> > Fixed in r234974.
> >> >>
> >> >>
> >> >> > +       VBTables) {
> >> >> >      StringRef VBTableName = VBTable.first;
> >> >> >      uint32_t Idx = 0;
> >> >> >      for (little32_t Offset : VBTable.second) {
> >> >> > @@ -363,7 +364,8 @@ static void dumpCXXData(const ObjectFile
> >> >> >        Idx += sizeof(Offset);
> >> >> >      }
> >> >> >    }
> >> >> > -  for (const std::pair<StringRef, CompleteObjectLocator> &COLPair
> :
> >> >> > COLs) {
> >> >> > +  for (const std::pair<const StringRef, CompleteObjectLocator>
> >> >> > &COLPair
> >> >> > :
> >> >> > +       COLs) {
> >> >> >      StringRef COLName = COLPair.first;
> >> >> >      const CompleteObjectLocator &COL = COLPair.second;
> >> >> >      outs() << COLName << "[IsImageRelative]: " << COL.Data[0] <<
> >> >> > '\n';
> >> >> > @@ -373,7 +375,8 @@ static void dumpCXXData(const ObjectFile
> >> >> >      outs() << COLName << "[ClassHierarchyDescriptor]: " <<
> >> >> > COL.Symbols[1]
> >> >> >             << '\n';
> >> >> >    }
> >> >> > -  for (const std::pair<StringRef, ClassHierarchyDescriptor>
> &CHDPair
> >> >> > :
> >> >> > CHDs) {
> >> >> > +  for (const std::pair<const StringRef, ClassHierarchyDescriptor>
> >> >> > &CHDPair :
> >> >> > +       CHDs) {
> >> >> >      StringRef CHDName = CHDPair.first;
> >> >> >      const ClassHierarchyDescriptor &CHD = CHDPair.second;
> >> >> >      outs() << CHDName << "[AlwaysZero]: " << CHD.Data[0] << '\n';
> >> >> > @@ -381,14 +384,14 @@ static void dumpCXXData(const ObjectFile
> >> >> >      outs() << CHDName << "[NumClasses]: " << CHD.Data[2] << '\n';
> >> >> >      outs() << CHDName << "[BaseClassArray]: " << CHD.Symbols[0] <<
> >> >> > '\n';
> >> >> >    }
> >> >> > -  for (const std::pair<std::pair<StringRef, uint64_t>, StringRef>
> >> >> > &BCAEntry :
> >> >> > -       BCAEntries) {
> >> >> > +  for (const std::pair<const std::pair<StringRef, uint64_t>,
> >> >> > StringRef>
> >> >>
> >> >> And "const auto &" here too, I suspect.
> >> >>
> >> >> > +           &BCAEntry : BCAEntries) {
> >> >> >      StringRef BCAName = BCAEntry.first.first;
> >> >> >      uint64_t Offset = BCAEntry.first.second;
> >> >> >      StringRef SymName = BCAEntry.second;
> >> >> >      outs() << BCAName << '[' << Offset << "]: " << SymName <<
> '\n';
> >> >> >    }
> >> >> > -  for (const std::pair<StringRef, BaseClassDescriptor> &BCDPair :
> >> >> > BCDs)
> >> >> > {
> >> >> > +  for (const std::pair<const StringRef, BaseClassDescriptor>
> >> >> > &BCDPair :
> >> >> > BCDs) {
> >> >>
> >> >> and here
> >> >>
> >> >> >      StringRef BCDName = BCDPair.first;
> >> >> >      const BaseClassDescriptor &BCD = BCDPair.second;
> >> >> >      outs() << BCDName << "[TypeDescriptor]: " << BCD.Symbols[0] <<
> >> >> > '\n';
> >> >> > @@ -400,7 +403,7 @@ static void dumpCXXData(const ObjectFile
> >> >> >      outs() << BCDName << "[ClassHierarchyDescriptor]: " <<
> >> >> > BCD.Symbols[1]
> >> >> >             << '\n';
> >> >> >    }
> >> >> > -  for (const std::pair<StringRef, TypeDescriptor> &TDPair : TDs) {
> >> >> > +  for (const std::pair<const StringRef, TypeDescriptor> &TDPair :
> >> >> > TDs)
> >> >> > {
> >> >>
> >> >> and here
> >> >>
> >> >> >      StringRef TDName = TDPair.first;
> >> >> >      const TypeDescriptor &TD = TDPair.second;
> >> >> >      outs() << TDName << "[VFPtr]: " << TD.Symbols[0] << '\n';
> >> >> > @@ -410,7 +413,7 @@ static void dumpCXXData(const ObjectFile
> >> >> >                           /*UseHexEscapes=*/true)
> >> >> >          << '\n';
> >> >> >    }
> >> >> > -  for (const std::pair<StringRef, ThrowInfo> &TIPair : TIs) {
> >> >> > +  for (const std::pair<const StringRef, ThrowInfo> &TIPair : TIs)
> {
> >> >>
> >> >> and here
> >> >>
> >> >> >      StringRef TIName = TIPair.first;
> >> >> >      const ThrowInfo &TI = TIPair.second;
> >> >> >      auto dumpThrowInfoFlag = [&](const char *Name, uint32_t Flag)
> {
> >> >> > @@ -429,7 +432,7 @@ static void dumpCXXData(const ObjectFile
> >> >> >      dumpThrowInfoSymbol("ForwardCompat", 8);
> >> >> >      dumpThrowInfoSymbol("CatchableTypeArray", 12);
> >> >> >    }
> >> >> > -  for (const std::pair<StringRef, CatchableTypeArray> &CTAPair :
> >> >> > CTAs)
> >> >> > {
> >> >> > +  for (const std::pair<const StringRef, CatchableTypeArray>
> &CTAPair
> >> >> > :
> >> >> > CTAs) {
> >> >>
> >> >> And here
> >> >>
> >> >> >      StringRef CTAName = CTAPair.first;
> >> >> >      const CatchableTypeArray &CTA = CTAPair.second;
> >> >> >
> >> >> > @@ -441,7 +444,7 @@ static void dumpCXXData(const ObjectFile
> >> >> >           I != E; ++I)
> >> >> >        outs() << CTAName << '[' << Idx++ << "]: " << I->second <<
> >> >> > '\n';
> >> >> >    }
> >> >> > -  for (const std::pair<StringRef, CatchableType> &CTPair : CTs) {
> >> >> > +  for (const std::pair<const StringRef, CatchableType> &CTPair :
> >> >> > CTs) {
> >> >>
> >> >> And here
> >> >>
> >> >> >      StringRef CTName = CTPair.first;
> >> >> >      const CatchableType &CT = CTPair.second;
> >> >> >      auto dumpCatchableTypeFlag = [&](const char *Name, uint32_t
> >> >> > Flag) {
> >> >> > @@ -464,14 +467,14 @@ static void dumpCXXData(const ObjectFile
> >> >> >             << "[CopyCtor]: " << (CT.Symbols[1].empty() ? "null" :
> >> >> > CT.Symbols[1])
> >> >> >             << '\n';
> >> >> >    }
> >> >> > -  for (const std::pair<std::pair<StringRef, uint64_t>, StringRef>
> >> >> > &VTTPair :
> >> >> > -       VTTEntries) {
> >> >> > +  for (const std::pair<const std::pair<StringRef, uint64_t>,
> >> >> > StringRef>
> >> >>
> >> >> And here
> >> >>
> >> >> > +           &VTTPair : VTTEntries) {
> >> >> >      StringRef VTTName = VTTPair.first.first;
> >> >> >      uint64_t VTTOffset = VTTPair.first.second;
> >> >> >      StringRef VTTEntry = VTTPair.second;
> >> >> >      outs() << VTTName << '[' << VTTOffset << "]: " << VTTEntry <<
> >> >> > '\n';
> >> >> >    }
> >> >> > -  for (const std::pair<StringRef, StringRef> &TIPair : TINames) {
> >> >> > +  for (const std::pair<const StringRef, StringRef> &TIPair :
> >> >> > TINames) {
> >> >>
> >> >> And here
> >> >>
> >> >> >      StringRef TIName = TIPair.first;
> >> >> >      outs() << TIName << ": " << TIPair.second << '\n';
> >> >> >    }
> >> >> >
> >> >> > Modified: llvm/trunk/utils/TableGen/CodeGenRegisters.cpp
> >> >> > URL:
> >> >> >
> >> >> >
> http://llvm.org/viewvc/llvm-project/llvm/trunk/utils/TableGen/CodeGenRegisters.cpp?rev=234963&r1=234962&r2=234963&view=diff
> >> >> >
> >> >> >
> >> >> >
> ==============================================================================
> >> >> > --- llvm/trunk/utils/TableGen/CodeGenRegisters.cpp (original)
> >> >> > +++ llvm/trunk/utils/TableGen/CodeGenRegisters.cpp Tue Apr 14
> >> >> > 20:21:15
> >> >> > 2015
> >> >> > @@ -1780,7 +1780,7 @@ void CodeGenRegBank::computeRegUnitLaneM
> >> >> >        const CodeGenRegister *SubRegister = S->second;
> >> >> >        unsigned LaneMask = SubRegIndex->LaneMask;
> >> >> >        // Distribute LaneMask to Register Units touched.
> >> >> > -      for (const auto &SUI : SubRegister->getRegUnits()) {
> >> >> > +      for (unsigned SUI : SubRegister->getRegUnits()) {
> >> >> >          bool Found = false;
> >> >> >          unsigned u = 0;
> >> >> >          for (unsigned RU : RegUnits) {
> >> >> >
> >> >> >
> >> >> > _______________________________________________
> >> >> > llvm-commits mailing list
> >> >> > llvm-commits at cs.uiuc.edu
> >> >> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> >> >
> >> >
> >
> >
>
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