[llvm] r252871 - Revert "Revert "[FunctionAttrs] Identify norecurse functions""

James Molloy via llvm-commits llvm-commits at lists.llvm.org
Thu Nov 12 08:17:36 PST 2015


Hi David,

Understood. I'll make my un-revert commit messages more detailed in future.

For the record, the problem was that the expected ordering of attribute
names when printed had changed (affecting function-attrs.ll). I'm still not
quite sure why this happened.

James

On Thu, 12 Nov 2015 at 16:14 David Blaikie via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

> On Thu, Nov 12, 2015 at 2:55 AM, James Molloy via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
>
>> Author: jamesm
>> Date: Thu Nov 12 04:55:20 2015
>> New Revision: 252871
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=252871&view=rev
>> Log:
>> Revert "Revert "[FunctionAttrs] Identify norecurse functions""
>>
>> This reapplies this patch, with test fixes.
>>
>
> It'd be helpful to detail the fixes (& whatever extra testing was involved
> (which buildbot scenarios failed, etc) in finding them) so that those
> changes can get extra scrutiny by anyone who's already reviewed the
> original patch & just wants to check the new changes.
>
>
>>
>> Added:
>>     llvm/trunk/test/Transforms/FunctionAttrs/norecurse.ll
>> Modified:
>>     llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp
>>     llvm/trunk/test/Analysis/TypeBasedAliasAnalysis/functionattrs.ll
>>     llvm/trunk/test/Transforms/FunctionAttrs/2008-09-03-ReadNone.ll
>>     llvm/trunk/test/Transforms/FunctionAttrs/2010-10-30-volatile.ll
>>     llvm/trunk/test/Transforms/FunctionAttrs/atomic.ll
>>     llvm/trunk/test/Transforms/FunctionAttrs/optnone.ll
>>
>> Modified: llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp?rev=252871&r1=252870&r2=252871&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp (original)
>> +++ llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp Thu Nov 12 04:55:20
>> 2015
>> @@ -50,6 +50,7 @@ STATISTIC(NumReadOnlyArg, "Number of arg
>>  STATISTIC(NumNoAlias, "Number of function returns marked noalias");
>>  STATISTIC(NumNonNullReturn, "Number of function returns marked nonnull");
>>  STATISTIC(NumAnnotated, "Number of attributes added to library
>> functions");
>> +STATISTIC(NumNoRecurse, "Number of functions marked as norecurse");
>>
>>  namespace {
>>  typedef SmallSetVector<Function *, 8> SCCNodeSet;
>> @@ -63,7 +64,12 @@ struct FunctionAttrs : public CallGraphS
>>    }
>>
>>    bool runOnSCC(CallGraphSCC &SCC) override;
>> -
>> +  bool doInitialization(CallGraph &CG) override {
>> +    Revisit.clear();
>> +    return false;
>> +  }
>> +  bool doFinalization(CallGraph &CG) override;
>> +
>>    void getAnalysisUsage(AnalysisUsage &AU) const override {
>>      AU.setPreservesCFG();
>>      AU.addRequired<AssumptionCacheTracker>();
>> @@ -73,6 +79,7 @@ struct FunctionAttrs : public CallGraphS
>>
>>  private:
>>    TargetLibraryInfo *TLI;
>> +  SmallVector<WeakVH,16> Revisit;
>>  };
>>  }
>>
>> @@ -976,6 +983,14 @@ static void setDoesNotAlias(Function &F,
>>    }
>>  }
>>
>> +static bool setDoesNotRecurse(Function &F) {
>> +  if (F.doesNotRecurse())
>> +    return false;
>> +  F.setDoesNotRecurse();
>> +  ++NumNoRecurse;
>> +  return true;
>> +}
>> +
>>  /// Analyze the name and prototype of the given function and set any
>> applicable
>>  /// attributes.
>>  ///
>> @@ -1779,6 +1794,55 @@ static bool inferPrototypeAttributes(Fun
>>    return true;
>>  }
>>
>> +static bool addNoRecurseAttrs(const CallGraphSCC &SCC,
>> +                              SmallVectorImpl<WeakVH> &Revisit) {
>> +  // Try and identify functions that do not recurse.
>> +
>> +  // If the SCC contains multiple nodes we know for sure there is
>> recursion.
>> +  if (!SCC.isSingular())
>> +    return false;
>> +
>> +  const CallGraphNode *CGN = *SCC.begin();
>> +  Function *F = CGN->getFunction();
>> +  if (!F || F->isDeclaration() || F->doesNotRecurse())
>> +    return false;
>> +
>> +  // If all of the calls in F are identifiable and are to norecurse
>> functions, F
>> +  // is norecurse. This check also detects self-recursion as F is not
>> currently
>> +  // marked norecurse, so any called from F to F will not be marked
>> norecurse.
>> +  if (std::all_of(CGN->begin(), CGN->end(),
>> +                  [](const CallGraphNode::CallRecord &CR) {
>> +                    Function *F = CR.second->getFunction();
>> +                    return F && F->doesNotRecurse();
>> +                  }))
>> +    // Function calls a potentially recursive function.
>> +    return setDoesNotRecurse(*F);
>> +
>> +  // We know that F is not obviously recursive, but we haven't been able
>> to
>> +  // prove that it doesn't actually recurse. Add it to the Revisit list
>> to try
>> +  // again top-down later.
>> +  Revisit.push_back(F);
>> +  return false;
>> +}
>> +
>> +static bool addNoRecurseAttrsTopDownOnly(Function *F) {
>> +  // If F is internal and all uses are in norecurse functions, then F is
>> also
>> +  // norecurse.
>> +  if (F->doesNotRecurse())
>> +    return false;
>> +  if (F->hasInternalLinkage()) {
>> +    for (auto *U : F->users())
>> +      if (auto *I = dyn_cast<Instruction>(U)) {
>> +        if (!I->getParent()->getParent()->doesNotRecurse())
>> +          return false;
>> +      } else {
>> +        return false;
>> +      }
>> +    return setDoesNotRecurse(*F);
>> +  }
>> +  return false;
>> +}
>> +
>>  bool FunctionAttrs::runOnSCC(CallGraphSCC &SCC) {
>>    TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
>>    bool Changed = false;
>> @@ -1826,6 +1890,19 @@ bool FunctionAttrs::runOnSCC(CallGraphSC
>>      Changed |= addNoAliasAttrs(SCCNodes);
>>      Changed |= addNonNullAttrs(SCCNodes, *TLI);
>>    }
>> +
>> +  Changed |= addNoRecurseAttrs(SCC, Revisit);
>> +  return Changed;
>> +}
>>
>> +bool FunctionAttrs::doFinalization(CallGraph &CG) {
>> +  bool Changed = false;
>> +  // When iterating over SCCs we visit functions in a bottom-up fashion.
>> Some of
>> +  // the rules we have for identifying norecurse functions work best
>> with a
>> +  // top-down walk, so look again at all the functions we previously
>> marked as
>> +  // worth revisiting, in top-down order.
>> +  for (auto &F : reverse(Revisit))
>> +    if (F)
>> +      Changed |= addNoRecurseAttrsTopDownOnly(cast<Function>((Value*)F));
>>    return Changed;
>>  }
>>
>> Modified: llvm/trunk/test/Analysis/TypeBasedAliasAnalysis/functionattrs.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/TypeBasedAliasAnalysis/functionattrs.ll?rev=252871&r1=252870&r2=252871&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/Analysis/TypeBasedAliasAnalysis/functionattrs.ll
>> (original)
>> +++ llvm/trunk/test/Analysis/TypeBasedAliasAnalysis/functionattrs.ll Thu
>> Nov 12 04:55:20 2015
>> @@ -30,7 +30,7 @@ define void @test1_yes(i32* %p) nounwind
>>    ret void
>>  }
>>
>> -; CHECK: define void @test1_no(i32* %p) #1 {
>> +; CHECK: define void @test1_no(i32* %p) #3 {
>>  define void @test1_no(i32* %p) nounwind {
>>    call void @callee(i32* %p), !tbaa !2
>>    ret void
>> @@ -72,9 +72,11 @@ define i32 @test3_no(i8* %p) nounwind {
>>  declare void @callee(i32* %p) nounwind
>>  declare void @llvm.memcpy.p0i8.p0i8.i64(i8*, i8*, i64, i32, i1) nounwind
>>
>> -; CHECK: attributes #0 = { nounwind readnone }
>> -; CHECK: attributes #1 = { nounwind }
>> +; CHECK: attributes #0 = { norecurse nounwind readnone }
>> +; CHECK: attributes #1 = { norecurse nounwind }
>>  ; CHECK: attributes #2 = { nounwind readonly }
>> +; CHECK: attributes #3 = { nounwind }
>> +; CHECK: attributes #4 = { argmemonly nounwind }
>>
>>  ; Root note.
>>  !0 = !{ }
>>
>> Modified: llvm/trunk/test/Transforms/FunctionAttrs/2008-09-03-ReadNone.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/FunctionAttrs/2008-09-03-ReadNone.ll?rev=252871&r1=252870&r2=252871&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/FunctionAttrs/2008-09-03-ReadNone.ll
>> (original)
>> +++ llvm/trunk/test/Transforms/FunctionAttrs/2008-09-03-ReadNone.ll Thu
>> Nov 12 04:55:20 2015
>> @@ -10,15 +10,16 @@ define i32 @f() {
>>         ret i32 %tmp
>>  }
>>
>> -; CHECK: define i32 @g() #0
>> +; CHECK: define i32 @g() #1
>>  define i32 @g() readonly {
>>         ret i32 0
>>  }
>>
>> -; CHECK: define i32 @h() #0
>> +; CHECK: define i32 @h() #1
>>  define i32 @h() readnone {
>>         %tmp = load i32, i32* @x                ; <i32> [#uses=1]
>>         ret i32 %tmp
>>  }
>>
>>  ; CHECK: attributes #0 = { readnone }
>> +; CHECK: attributes #1 = { norecurse readnone }
>>
>> Modified: llvm/trunk/test/Transforms/FunctionAttrs/2010-10-30-volatile.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/FunctionAttrs/2010-10-30-volatile.ll?rev=252871&r1=252870&r2=252871&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/FunctionAttrs/2010-10-30-volatile.ll
>> (original)
>> +++ llvm/trunk/test/Transforms/FunctionAttrs/2010-10-30-volatile.ll Thu
>> Nov 12 04:55:20 2015
>> @@ -4,7 +4,9 @@
>>  @g = constant i32 1
>>
>>  define void @foo() {
>> -; CHECK: void @foo() {
>> +; CHECK: void @foo() #0 {
>>    %tmp = load volatile i32, i32* @g
>>    ret void
>>  }
>> +
>> +; CHECK: attributes #0 = { norecurse }
>>
>> Modified: llvm/trunk/test/Transforms/FunctionAttrs/atomic.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/FunctionAttrs/atomic.ll?rev=252871&r1=252870&r2=252871&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/FunctionAttrs/atomic.ll (original)
>> +++ llvm/trunk/test/Transforms/FunctionAttrs/atomic.ll Thu Nov 12
>> 04:55:20 2015
>> @@ -19,5 +19,5 @@ entry:
>>    ret i32 %r
>>  }
>>
>> -; CHECK: attributes #0 = { readnone ssp uwtable }
>> -; CHECK: attributes #1 = { ssp uwtable }
>> +; CHECK: attributes #0 = { norecurse readnone ssp uwtable }
>> +; CHECK: attributes #1 = { norecurse ssp uwtable }
>>
>> Added: llvm/trunk/test/Transforms/FunctionAttrs/norecurse.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/FunctionAttrs/norecurse.ll?rev=252871&view=auto
>>
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/FunctionAttrs/norecurse.ll (added)
>> +++ llvm/trunk/test/Transforms/FunctionAttrs/norecurse.ll Thu Nov 12
>> 04:55:20 2015
>> @@ -0,0 +1,57 @@
>> +; RUN: opt < %s -basicaa -functionattrs -S | FileCheck %s
>> +
>> +; CHECK: define i32 @leaf() #0
>> +define i32 @leaf() {
>> +  ret i32 1
>> +}
>> +
>> +; CHECK: define i32 @self_rec() #1
>> +define i32 @self_rec() {
>> +  %a = call i32 @self_rec()
>> +  ret i32 4
>> +}
>> +
>> +; CHECK: define i32 @indirect_rec() #1
>> +define i32 @indirect_rec() {
>> +  %a = call i32 @indirect_rec2()
>> +  ret i32 %a
>> +}
>> +; CHECK: define i32 @indirect_rec2() #1
>> +define i32 @indirect_rec2() {
>> +  %a = call i32 @indirect_rec()
>> +  ret i32 %a
>> +}
>> +
>> +; CHECK: define i32 @extern() #1
>> +define i32 @extern() {
>> +  %a = call i32 @k()
>> +  ret i32 %a
>> +}
>> +declare i32 @k() readnone
>> +
>> +; CHECK: define internal i32 @called_by_norecurse() #0
>> +define internal i32 @called_by_norecurse() {
>> +  %a = call i32 @k()
>> +  ret i32 %a
>> +}
>> +define void @m() norecurse {
>> +  %a = call i32 @called_by_norecurse()
>> +  ret void
>> +}
>> +
>> +; CHECK: define internal i32 @called_by_norecurse_indirectly() #0
>> +define internal i32 @called_by_norecurse_indirectly() {
>> +  %a = call i32 @k()
>> +  ret i32 %a
>> +}
>> +define internal void @o() {
>> +  %a = call i32 @called_by_norecurse_indirectly()
>> +  ret void
>> +}
>> +define void @p() norecurse {
>> +  call void @o()
>> +  ret void
>> +}
>> +
>> +; CHECK: attributes #0 = { norecurse readnone }
>> +; CHECK: attributes #1 = { readnone }
>>
>> Modified: llvm/trunk/test/Transforms/FunctionAttrs/optnone.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/FunctionAttrs/optnone.ll?rev=252871&r1=252870&r2=252871&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/FunctionAttrs/optnone.ll (original)
>> +++ llvm/trunk/test/Transforms/FunctionAttrs/optnone.ll Thu Nov 12
>> 04:55:20 2015
>> @@ -16,9 +16,11 @@ define void @test_optnone(i8* %p) noinli
>>
>>  declare i8 @strlen(i8*) noinline optnone
>>  ; CHECK-LABEL: @strlen
>> -; CHECK: (i8*) #1
>> +; CHECK: (i8*) #2
>>
>>  ; CHECK-LABEL: attributes #0
>> -; CHECK: = { readnone }
>> +; CHECK: = { norecurse readnone }
>>  ; CHECK-LABEL: attributes #1
>> +; CHECK: = { noinline norecurse optnone }
>> +; CHECK-LABEL: attributes #2
>>  ; CHECK: = { noinline optnone }
>>
>>
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