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Restrict somewhat the memory-allocation pointer cmp opt from r223093
Based on review comments from Richard Smith, restrict this optimization from applying to globals that might resolve lazily to other dynamically-loaded modules, and also from dynamic allocas (which might be transformed into malloc calls). In short, take extra care that the compared-to pointer is really simultaneously live with the memory allocation. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223347 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hal Finkel
parent
9ce01153e0
commit
d70d5148a6
@ -2026,12 +2026,22 @@ static Constant *computePointerICmp(const DataLayout *DL,
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};
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// Is the set of underlying objects all things which must be disjoint from
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// noalias calls.
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// noalias calls. For allocas, we consider only static ones (dynamic
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// allocas might be transformed into calls to malloc not simultaneously
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// live with the compared-to allocation). For globals, we exclude symbols
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// that might be resolve lazily to symbols in another dynamically-loaded
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// library (and, thus, could be malloc'ed by the implementation).
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auto IsAllocDisjoint = [](SmallVectorImpl<Value *> &Objects) {
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return std::all_of(Objects.begin(), Objects.end(),
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[](Value *V){
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if (isa<AllocaInst>(V) || isa<GlobalValue>(V))
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return true;
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if (const AllocaInst *AI = dyn_cast<AllocaInst>(V))
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return AI->isStaticAlloca();
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if (const GlobalValue *GV = dyn_cast<GlobalValue>(V))
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return (GV->hasLocalLinkage() ||
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GV->hasHiddenVisibility() ||
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GV->hasProtectedVisibility() ||
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GV->hasUnnamedAddr()) &&
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!GV->isThreadLocal();
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if (const Argument *A = dyn_cast<Argument>(V))
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return A->hasByValAttr();
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return false;
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@ -3,6 +3,11 @@ target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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@g1 = global i32 0, align 4
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@g2 = internal global i32 0, align 4
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@g3 = unnamed_addr global i32 0, align 4
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@g4 = hidden global i32 0, align 4
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@g5 = protected global i32 0, align 4
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@g6 = thread_local unnamed_addr global i32 0, align 4
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; Make sure we can simplify away a pointer comparison between
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; dynamically-allocated memory and a local stack allocation.
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@ -43,7 +48,7 @@ define void @_Z2p2bb(i1 zeroext %b1, i1 zeroext %b2) #0 {
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%mStackData = alloca [10 x i32], align 16
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%1 = bitcast [10 x i32]* %mStackData to i8*
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%2 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
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%3 = select i1 %b1, i32* %2, i32* @g1
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%3 = select i1 %b1, i32* %2, i32* @g2
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%4 = tail call noalias i8* @_Znam(i64 48) #4
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%5 = tail call noalias i8* @_Znam(i64 48) #4
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%.v = select i1 %b2, i8* %4, i8* %5
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@ -64,6 +69,81 @@ define void @_Z2p2bb(i1 zeroext %b1, i1 zeroext %b2) #0 {
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ret void
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}
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define void @_Z2p4bb(i1 zeroext %b1, i1 zeroext %b2) #0 {
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%mStackData = alloca [10 x i32], align 16
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%1 = bitcast [10 x i32]* %mStackData to i8*
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%2 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
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%3 = select i1 %b1, i32* %2, i32* @g3
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%4 = tail call noalias i8* @_Znam(i64 48) #4
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%5 = tail call noalias i8* @_Znam(i64 48) #4
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%.v = select i1 %b2, i8* %4, i8* %5
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%6 = bitcast i8* %.v to i32*
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%7 = icmp eq i32* %6, %3
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br i1 %7, label %9, label %8
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; CHECK-LABEL: @_Z2p4bb
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; CHECK-NOT: icmp
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; CHECK: ret void
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; <label>:8 ; preds = %0
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call void @_ZdaPv(i8* %4) #5
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call void @_ZdaPv(i8* %5) #5
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br label %9
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; <label>:9 ; preds = %0, %8
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ret void
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}
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define void @_Z2p5bb(i1 zeroext %b1, i1 zeroext %b2) #0 {
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%mStackData = alloca [10 x i32], align 16
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%1 = bitcast [10 x i32]* %mStackData to i8*
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%2 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
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%3 = select i1 %b1, i32* %2, i32* @g4
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%4 = tail call noalias i8* @_Znam(i64 48) #4
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%5 = tail call noalias i8* @_Znam(i64 48) #4
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%.v = select i1 %b2, i8* %4, i8* %5
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%6 = bitcast i8* %.v to i32*
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%7 = icmp eq i32* %6, %3
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br i1 %7, label %9, label %8
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; CHECK-LABEL: @_Z2p5bb
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; CHECK-NOT: icmp
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; CHECK: ret void
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; <label>:8 ; preds = %0
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call void @_ZdaPv(i8* %4) #5
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call void @_ZdaPv(i8* %5) #5
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br label %9
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; <label>:9 ; preds = %0, %8
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ret void
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}
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define void @_Z2p6bb(i1 zeroext %b1, i1 zeroext %b2) #0 {
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%mStackData = alloca [10 x i32], align 16
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%1 = bitcast [10 x i32]* %mStackData to i8*
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%2 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
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%3 = select i1 %b1, i32* %2, i32* @g5
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%4 = tail call noalias i8* @_Znam(i64 48) #4
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%5 = tail call noalias i8* @_Znam(i64 48) #4
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%.v = select i1 %b2, i8* %4, i8* %5
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%6 = bitcast i8* %.v to i32*
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%7 = icmp eq i32* %6, %3
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br i1 %7, label %9, label %8
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; CHECK-LABEL: @_Z2p6bb
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; CHECK-NOT: icmp
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; CHECK: ret void
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; <label>:8 ; preds = %0
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call void @_ZdaPv(i8* %4) #5
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call void @_ZdaPv(i8* %5) #5
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br label %9
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; <label>:9 ; preds = %0, %8
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ret void
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}
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; Here's another case involving multiple underlying objects, but this time we
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; must keep the comparison (it might involve a regular pointer-typed function
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; argument).
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@ -93,6 +173,77 @@ define void @_Z4nopebbPi(i1 zeroext %b1, i1 zeroext %b2, i32* readnone %q) #0 {
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ret void
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}
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define void @_Z2p3bb(i1 zeroext %b1, i1 zeroext %b2) #0 {
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%mStackData = alloca [10 x i32], align 16
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%1 = bitcast [10 x i32]* %mStackData to i8*
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%2 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
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%3 = select i1 %b1, i32* %2, i32* @g1
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%4 = tail call noalias i8* @_Znam(i64 48) #4
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%5 = tail call noalias i8* @_Znam(i64 48) #4
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%.v = select i1 %b2, i8* %4, i8* %5
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%6 = bitcast i8* %.v to i32*
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%7 = icmp eq i32* %6, %3
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br i1 %7, label %9, label %8
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; CHECK-LABEL: @_Z2p3bb
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; CHECK: icmp
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; CHECK: ret void
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; <label>:8 ; preds = %0
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call void @_ZdaPv(i8* %4) #5
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call void @_ZdaPv(i8* %5) #5
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br label %9
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; <label>:9 ; preds = %0, %8
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ret void
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}
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define void @_Z2p7bb(i1 zeroext %b1, i1 zeroext %b2) #0 {
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%mStackData = alloca [10 x i32], align 16
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%1 = bitcast [10 x i32]* %mStackData to i8*
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%2 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
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%3 = select i1 %b1, i32* %2, i32* @g6
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%4 = tail call noalias i8* @_Znam(i64 48) #4
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%5 = tail call noalias i8* @_Znam(i64 48) #4
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%.v = select i1 %b2, i8* %4, i8* %5
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%6 = bitcast i8* %.v to i32*
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%7 = icmp eq i32* %6, %3
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br i1 %7, label %9, label %8
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; CHECK-LABEL: @_Z2p7bb
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; CHECK: icmp
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; CHECK: ret void
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; <label>:8 ; preds = %0
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call void @_ZdaPv(i8* %4) #5
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call void @_ZdaPv(i8* %5) #5
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br label %9
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; <label>:9 ; preds = %0, %8
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ret void
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}
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define void @_Z2p2v(i32 %c) #0 {
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%mStackData = alloca [10 x i32], i32 %c, align 16
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%1 = bitcast [10 x i32]* %mStackData to i8*
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%2 = tail call noalias i8* @_Znam(i64 48) #4
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%3 = bitcast i8* %2 to i32*
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%4 = getelementptr inbounds [10 x i32]* %mStackData, i64 0, i64 0
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%5 = icmp eq i32* %3, %4
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br i1 %5, label %7, label %6
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; CHECK-LABEL: @_Z2p2v
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; CHECK: icmp
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; CHECK: ret void
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; <label>:6 ; preds = %0
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call void @_ZdaPv(i8* %2) #5
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br label %7
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; <label>:7 ; preds = %0, %6
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ret void
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}
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; Function Attrs: nobuiltin
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declare noalias i8* @_Znam(i64) #2
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