[llvm] dbc16ed - [GlobalOpt] Revert valgrind hacks

David Blaikie via llvm-commits llvm-commits at lists.llvm.org
Tue Apr 13 22:29:46 PDT 2021


Please include more detail in commit messages - it looks like all the
detail from the phab review wasn't included/was lost here.

On Tue, Apr 13, 2021 at 9:11 AM Evgeny Leviant via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
>
>
> Author: Evgeny Leviant
> Date: 2021-04-13T19:11:10+03:00
> New Revision: dbc16ed199dce2598f0e49943bf8354ef92a0ecc
>
> URL: https://github.com/llvm/llvm-project/commit/dbc16ed199dce2598f0e49943bf8354ef92a0ecc
> DIFF: https://github.com/llvm/llvm-project/commit/dbc16ed199dce2598f0e49943bf8354ef92a0ecc.diff
>
> LOG: [GlobalOpt] Revert valgrind hacks
>
> Differential revision: https://reviews.llvm.org/D69428
>
> Added:
>
>
> Modified:
>     llvm/lib/Transforms/IPO/GlobalOpt.cpp
>     llvm/test/ThinLTO/X86/import-constant.ll
>     llvm/test/Transforms/GlobalOpt/2009-11-16-BrokenPerformHeapAllocSRoA.ll
>     llvm/test/Transforms/GlobalOpt/cleanup-pointer-root-users.ll
>     llvm/test/Transforms/GlobalOpt/dead-store-status.ll
>
> Removed:
>
>
>
> ################################################################################
> diff  --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
> index f275f371c77ae..7c6c4452b9186 100644
> --- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
> +++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
> @@ -106,175 +106,6 @@ static cl::opt<int> ColdCCRelFreq(
>          "entry frequency, for a call site to be considered cold for enabling"
>          "coldcc"));
>
> -/// Is this global variable possibly used by a leak checker as a root?  If so,
> -/// we might not really want to eliminate the stores to it.
> -static bool isLeakCheckerRoot(GlobalVariable *GV) {
> -  // A global variable is a root if it is a pointer, or could plausibly contain
> -  // a pointer.  There are two challenges; one is that we could have a struct
> -  // the has an inner member which is a pointer.  We recurse through the type to
> -  // detect these (up to a point).  The other is that we may actually be a union
> -  // of a pointer and another type, and so our LLVM type is an integer which
> -  // gets converted into a pointer, or our type is an [i8 x #] with a pointer
> -  // potentially contained here.
> -
> -  if (GV->hasPrivateLinkage())
> -    return false;
> -
> -  SmallVector<Type *, 4> Types;
> -  Types.push_back(GV->getValueType());
> -
> -  unsigned Limit = 20;
> -  do {
> -    Type *Ty = Types.pop_back_val();
> -    switch (Ty->getTypeID()) {
> -      default: break;
> -      case Type::PointerTyID:
> -        return true;
> -      case Type::FixedVectorTyID:
> -      case Type::ScalableVectorTyID:
> -        if (cast<VectorType>(Ty)->getElementType()->isPointerTy())
> -          return true;
> -        break;
> -      case Type::ArrayTyID:
> -        Types.push_back(cast<ArrayType>(Ty)->getElementType());
> -        break;
> -      case Type::StructTyID: {
> -        StructType *STy = cast<StructType>(Ty);
> -        if (STy->isOpaque()) return true;
> -        for (StructType::element_iterator I = STy->element_begin(),
> -                 E = STy->element_end(); I != E; ++I) {
> -          Type *InnerTy = *I;
> -          if (isa<PointerType>(InnerTy)) return true;
> -          if (isa<StructType>(InnerTy) || isa<ArrayType>(InnerTy) ||
> -              isa<VectorType>(InnerTy))
> -            Types.push_back(InnerTy);
> -        }
> -        break;
> -      }
> -    }
> -    if (--Limit == 0) return true;
> -  } while (!Types.empty());
> -  return false;
> -}
> -
> -/// Given a value that is stored to a global but never read, determine whether
> -/// it's safe to remove the store and the chain of computation that feeds the
> -/// store.
> -static bool IsSafeComputationToRemove(
> -    Value *V, function_ref<TargetLibraryInfo &(Function &)> GetTLI) {
> -  do {
> -    if (isa<Constant>(V))
> -      return true;
> -    if (!V->hasOneUse())
> -      return false;
> -    if (isa<LoadInst>(V) || isa<InvokeInst>(V) || isa<Argument>(V) ||
> -        isa<GlobalValue>(V))
> -      return false;
> -    if (isAllocationFn(V, GetTLI))
> -      return true;
> -
> -    Instruction *I = cast<Instruction>(V);
> -    if (I->mayHaveSideEffects())
> -      return false;
> -    if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I)) {
> -      if (!GEP->hasAllConstantIndices())
> -        return false;
> -    } else if (I->getNumOperands() != 1) {
> -      return false;
> -    }
> -
> -    V = I->getOperand(0);
> -  } while (true);
> -}
> -
> -/// This GV is a pointer root.  Loop over all users of the global and clean up
> -/// any that obviously don't assign the global a value that isn't dynamically
> -/// allocated.
> -static bool
> -CleanupPointerRootUsers(GlobalVariable *GV,
> -                        function_ref<TargetLibraryInfo &(Function &)> GetTLI) {
> -  // A brief explanation of leak checkers.  The goal is to find bugs where
> -  // pointers are forgotten, causing an accumulating growth in memory
> -  // usage over time.  The common strategy for leak checkers is to explicitly
> -  // allow the memory pointed to by globals at exit.  This is popular because it
> -  // also solves another problem where the main thread of a C++ program may shut
> -  // down before other threads that are still expecting to use those globals. To
> -  // handle that case, we expect the program may create a singleton and never
> -  // destroy it.
> -
> -  bool Changed = false;
> -
> -  // If Dead[n].first is the only use of a malloc result, we can delete its
> -  // chain of computation and the store to the global in Dead[n].second.
> -  SmallVector<std::pair<Instruction *, Instruction *>, 32> Dead;
> -
> -  // Constants can't be pointers to dynamically allocated memory.
> -  for (Value::user_iterator UI = GV->user_begin(), E = GV->user_end();
> -       UI != E;) {
> -    User *U = *UI++;
> -    if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
> -      Value *V = SI->getValueOperand();
> -      if (isa<Constant>(V)) {
> -        Changed = true;
> -        SI->eraseFromParent();
> -      } else if (Instruction *I = dyn_cast<Instruction>(V)) {
> -        if (I->hasOneUse())
> -          Dead.push_back(std::make_pair(I, SI));
> -      }
> -    } else if (MemSetInst *MSI = dyn_cast<MemSetInst>(U)) {
> -      if (isa<Constant>(MSI->getValue())) {
> -        Changed = true;
> -        MSI->eraseFromParent();
> -      } else if (Instruction *I = dyn_cast<Instruction>(MSI->getValue())) {
> -        if (I->hasOneUse())
> -          Dead.push_back(std::make_pair(I, MSI));
> -      }
> -    } else if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(U)) {
> -      GlobalVariable *MemSrc = dyn_cast<GlobalVariable>(MTI->getSource());
> -      if (MemSrc && MemSrc->isConstant()) {
> -        Changed = true;
> -        MTI->eraseFromParent();
> -      } else if (Instruction *I = dyn_cast<Instruction>(MemSrc)) {
> -        if (I->hasOneUse())
> -          Dead.push_back(std::make_pair(I, MTI));
> -      }
> -    } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
> -      if (CE->use_empty()) {
> -        CE->destroyConstant();
> -        Changed = true;
> -      }
> -    } else if (Constant *C = dyn_cast<Constant>(U)) {
> -      if (isSafeToDestroyConstant(C)) {
> -        C->destroyConstant();
> -        // This could have invalidated UI, start over from scratch.
> -        Dead.clear();
> -        CleanupPointerRootUsers(GV, GetTLI);
> -        return true;
> -      }
> -    }
> -  }
> -
> -  for (int i = 0, e = Dead.size(); i != e; ++i) {
> -    if (IsSafeComputationToRemove(Dead[i].first, GetTLI)) {
> -      Dead[i].second->eraseFromParent();
> -      Instruction *I = Dead[i].first;
> -      do {
> -        if (isAllocationFn(I, GetTLI))
> -          break;
> -        Instruction *J = dyn_cast<Instruction>(I->getOperand(0));
> -        if (!J)
> -          break;
> -        I->eraseFromParent();
> -        I = J;
> -      } while (true);
> -      I->eraseFromParent();
> -      Changed = true;
> -    }
> -  }
> -
> -  return Changed;
> -}
> -
>  /// We just marked GV constant.  Loop over all users of the global, cleaning up
>  /// the obvious ones.  This is largely just a quick scan over the use list to
>  /// clean up the easy and obvious cruft.  This returns true if it made a change.
> @@ -823,12 +654,8 @@ static bool OptimizeAwayTrappingUsesOfLoads(
>    // If we nuked all of the loads, then none of the stores are needed either,
>    // nor is the global.
>    if (AllNonStoreUsesGone) {
> -    if (isLeakCheckerRoot(GV)) {
> -      Changed |= CleanupPointerRootUsers(GV, GetTLI);
> -    } else {
> -      Changed = true;
> -      CleanupConstantGlobalUsers(GV, nullptr, DL, GetTLI);
> -    }
> +    Changed = true;
> +    CleanupConstantGlobalUsers(GV, nullptr, DL, GetTLI);
>      if (GV->use_empty()) {
>        LLVM_DEBUG(dbgs() << "  *** GLOBAL NOW DEAD!\n");
>        Changed = true;
> @@ -1997,15 +1824,10 @@ processInternalGlobal(GlobalVariable *GV, const GlobalStatus &GS,
>    if (!GS.IsLoaded) {
>      LLVM_DEBUG(dbgs() << "GLOBAL NEVER LOADED: " << *GV << "\n");
>
> -    if (isLeakCheckerRoot(GV)) {
> -      // Delete any constant stores to the global.
> -      Changed = CleanupPointerRootUsers(GV, GetTLI);
> -    } else {
> -      // Delete any stores we can find to the global.  We may not be able to
> -      // make it completely dead though.
> -      Changed =
> -          CleanupConstantGlobalUsers(GV, GV->getInitializer(), DL, GetTLI);
> -    }
> +    // Delete any stores we can find to the global.  We may not be able to
> +    // make it completely dead though.
> +    Changed =
> +        CleanupConstantGlobalUsers(GV, GV->getInitializer(), DL, GetTLI);
>
>      // If the global is dead now, delete it.
>      if (GV->use_empty()) {
>
> diff  --git a/llvm/test/ThinLTO/X86/import-constant.ll b/llvm/test/ThinLTO/X86/import-constant.ll
> index 1bc2a1c2f7a4d..5e8fa43d14002 100644
> --- a/llvm/test/ThinLTO/X86/import-constant.ll
> +++ b/llvm/test/ThinLTO/X86/import-constant.ll
> @@ -32,11 +32,8 @@
>  ; IMPORT-NEXT: @_ZL3Obj.llvm.{{.*}} = available_externally hidden constant %struct.S { i32 4, i32 8, i32* @val }
>  ; IMPORT-NEXT: @val = available_externally global i32 42
>
> -; OPT: @outer = internal unnamed_addr global %struct.Q zeroinitializer
> -
>  ; OPT:      define dso_local i32 @main()
>  ; OPT-NEXT: entry:
> -; OPT-NEXT:   store %struct.S* null, %struct.S** getelementptr inbounds (%struct.Q, %struct.Q* @outer, i64 0, i32 0)
>  ; OPT-NEXT:   ret i32 12
>
>  ; NOREFS:      @outer = internal local_unnamed_addr global %struct.Q zeroinitializer
>
> diff  --git a/llvm/test/Transforms/GlobalOpt/2009-11-16-BrokenPerformHeapAllocSRoA.ll b/llvm/test/Transforms/GlobalOpt/2009-11-16-BrokenPerformHeapAllocSRoA.ll
> index 461c25316e91a..a997a948b3cda 100644
> --- a/llvm/test/Transforms/GlobalOpt/2009-11-16-BrokenPerformHeapAllocSRoA.ll
> +++ b/llvm/test/Transforms/GlobalOpt/2009-11-16-BrokenPerformHeapAllocSRoA.ll
> @@ -17,7 +17,7 @@ define void @test() nounwind ssp {
>    %2 = sext i32 %1 to i64                         ; <i64> [#uses=1]
>    %3 = mul i64 %2, ptrtoint (%struct.strchartype* getelementptr (%struct.strchartype, %struct.strchartype* null, i64 1) to i64) ; <i64> [#uses=1]
>    %4 = tail call i8* @malloc(i64 %3)              ; <i8*> [#uses=1]
> -; CHECK-NOT: call i8* @malloc(i64
> +; CHECK: call i8* @malloc(i64
>    %5 = bitcast i8* %4 to %struct.strchartype*     ; <%struct.strchartype*> [#uses=1]
>    store %struct.strchartype* %5, %struct.strchartype** @chartypes, align 8
>    ret void
>
> diff  --git a/llvm/test/Transforms/GlobalOpt/cleanup-pointer-root-users.ll b/llvm/test/Transforms/GlobalOpt/cleanup-pointer-root-users.ll
> index 16da5315db0c3..e69de29bb2d1d 100644
> --- a/llvm/test/Transforms/GlobalOpt/cleanup-pointer-root-users.ll
> +++ b/llvm/test/Transforms/GlobalOpt/cleanup-pointer-root-users.ll
> @@ -1,49 +0,0 @@
> -; RUN: opt -globalopt -S -o - < %s | FileCheck %s
> -
> - at glbl = internal global i8* null
> -
> -define void @test1a() {
> -; CHECK-LABEL: @test1a(
> -; CHECK-NOT: store
> -; CHECK-NEXT: ret void
> -  store i8* null, i8** @glbl
> -  ret void
> -}
> -
> -define void @test1b(i8* %p) {
> -; CHECK-LABEL: @test1b(
> -; CHECK-NEXT: store
> -; CHECK-NEXT: ret void
> -  store i8* %p, i8** @glbl
> -  ret void
> -}
> -
> -define void @test2() {
> -; CHECK-LABEL: @test2(
> -; CHECK: alloca i8
> -  %txt = alloca i8
> -  call void @foo2(i8* %txt)
> -  %call2 = call i8* @strdup(i8* %txt)
> -  store i8* %call2, i8** @glbl
> -  ret void
> -}
> -declare i8* @strdup(i8*)
> -declare void @foo2(i8*)
> -
> -define void @test3() uwtable personality i32 (i32, i64, i8*, i8*)* @__gxx_personality_v0 {
> -; CHECK-LABEL: @test3(
> -; CHECK-NOT: bb1:
> -; CHECK-NOT: bb2:
> -; CHECK: invoke
> -  %ptr = invoke i8* @_Znwm(i64 1)
> -          to label %bb1 unwind label %bb2
> -bb1:
> -  store i8* %ptr, i8** @glbl
> -  unreachable
> -bb2:
> -  %tmp1 = landingpad { i8*, i32 }
> -          cleanup
> -  resume { i8*, i32 } %tmp1
> -}
> -declare i32 @__gxx_personality_v0(i32, i64, i8*, i8*)
> -declare i8* @_Znwm(i64)
>
> diff  --git a/llvm/test/Transforms/GlobalOpt/dead-store-status.ll b/llvm/test/Transforms/GlobalOpt/dead-store-status.ll
> index afd1f9f6cabfd..472164006eea8 100644
> --- a/llvm/test/Transforms/GlobalOpt/dead-store-status.ll
> +++ b/llvm/test/Transforms/GlobalOpt/dead-store-status.ll
> @@ -1,10 +1,10 @@
> -; RUN: opt < %s -globalopt -S | FileCheck %s
> +; RUN: opt < %s -globalopt -instcombine -S | FileCheck %s
>
>  ; When removing the store to @global in @foo, the pass would incorrectly return
>  ; false. This was caught by the pass return status check that is hidden under
>  ; EXPENSIVE_CHECKS.
>
> -; CHECK: @global = internal unnamed_addr global i16* null, align 1
> +; CHECK-NOT: @global = internal unnamed_addr global i16* null, align 1
>
>  ; CHECK-LABEL: @foo
>  ; CHECK-NEXT: entry:
>
>
>
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