[llvm-dev] Should we enable -Wrange-loop-analysis? (Was: [llvm] r261524 - Fix some abuse of auto...)

[Mehdi Amini via llvm-dev]

What does this warning look like (and what cases does it catch)? Also does it have false positive?

-- 
Mehdi

> On Mar 18, 2016, at 5:12 PM, Justin Bogner via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> This is a pretty nice warning. Should we enable it for LLVM's build when
> the host compiler supports it?
> 
> Benjamin Kramer via llvm-commits <llvm-commits at lists.llvm.org> writes:
>> Author: d0k
>> Date: Mon Feb 22 07:11:58 2016
>> New Revision: 261524
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=261524&view=rev
>> Log:
>> Fix some abuse of auto flagged by clang's -Wrange-loop-analysis.
>> 
>> Modified:
>>    llvm/trunk/lib/Target/PowerPC/PPCBoolRetToInt.cpp
>>    llvm/trunk/lib/Transforms/Utils/MemorySSA.cpp
>>    llvm/trunk/tools/sancov/sancov.cc
>> 
>> Modified: llvm/trunk/lib/Target/PowerPC/PPCBoolRetToInt.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCBoolRetToInt.cpp?rev=261524&r1=261523&r2=261524&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/PowerPC/PPCBoolRetToInt.cpp (original)
>> +++ llvm/trunk/lib/Target/PowerPC/PPCBoolRetToInt.cpp Mon Feb 22 07:11:58 2016
>> @@ -119,7 +119,7 @@ class PPCBoolRetToInt : public FunctionP
>>             Promotable.insert(P);
>> 
>>     SmallVector<const PHINode *, 8> ToRemove;
>> -    for (const auto &P : Promotable) {
>> +    for (const PHINode *P : Promotable) {
>>       // Condition 2 and 3
>>       auto IsValidUser = [] (const Value *V) -> bool {
>>         return isa<ReturnInst>(V) || isa<CallInst>(V) || isa<PHINode>(V) ||
>> @@ -146,7 +146,7 @@ class PPCBoolRetToInt : public FunctionP
>>         Promotable.erase(User);
>>       ToRemove.clear();
>> 
>> -      for (const auto &P : Promotable) {
>> +      for (const PHINode *P : Promotable) {
>>         // Condition 4 and 5
>>         const auto &Users = P->users();
>>         const auto &Operands = P->operands();
>> @@ -199,11 +199,11 @@ class PPCBoolRetToInt : public FunctionP
>>     // Presently, we only know how to handle PHINode, Constant, and Arguments.
>>     // Potentially, bitwise operations (AND, OR, XOR, NOT) and sign extension
>>     // could also be handled in the future.
>> -    for (const auto &V : Defs)
>> +    for (Value *V : Defs)
>>       if (!isa<PHINode>(V) && !isa<Constant>(V) && !isa<Argument>(V))
>>         return false;
>> 
>> -    for (const auto &V : Defs)
>> +    for (Value *V : Defs)
>>       if (const PHINode *P = dyn_cast<PHINode>(V))
>>         if (!PromotablePHINodes.count(P))
>>           return false;
>> @@ -214,7 +214,7 @@ class PPCBoolRetToInt : public FunctionP
>>       ++NumBoolCallPromotion;
>>     ++NumBoolToIntPromotion;
>> 
>> -    for (const auto &V : Defs)
>> +    for (Value *V : Defs)
>>       if (!BoolToIntMap.count(V))
>>         BoolToIntMap[V] = translate(V);
>> 
>> 
>> Modified: llvm/trunk/lib/Transforms/Utils/MemorySSA.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/MemorySSA.cpp?rev=261524&r1=261523&r2=261524&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/Utils/MemorySSA.cpp (original)
>> +++ llvm/trunk/lib/Transforms/Utils/MemorySSA.cpp Mon Feb 22 07:11:58 2016
>> @@ -473,7 +473,7 @@ void MemorySSA::verifyDomination(Functio
>>       if (!MD)
>>         continue;
>> 
>> -      for (const auto &U : MD->users()) {
>> +      for (User *U : MD->users()) {
>>         BasicBlock *UseBlock;
>>         // Things are allowed to flow to phi nodes over their predecessor edge.
>>         if (auto *P = dyn_cast<MemoryPhi>(U)) {
>> 
>> Modified: llvm/trunk/tools/sancov/sancov.cc
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/sancov/sancov.cc?rev=261524&r1=261523&r2=261524&view=diff
>> ==============================================================================
>> --- llvm/trunk/tools/sancov/sancov.cc (original)
>> +++ llvm/trunk/tools/sancov/sancov.cc Mon Feb 22 07:11:58 2016
>> @@ -364,7 +364,7 @@ static void getObjectCoveragePoints(cons
>>   if (SanCovAddrs.empty())
>>     Fail("__sanitizer_cov* functions not found");
>> 
>> -  for (const auto Section : O.sections()) {
>> +  for (object::SectionRef Section : O.sections()) {
>>     if (Section.isVirtual() || !Section.isText()) // llvm-objdump does the same.
>>       continue;
>>     uint64_t SectionAddr = Section.getAddress();
>> 
>> 
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