Commit 0d824c98 authored by Hans Wennborg's avatar Hans Wennborg
Browse files

Merging r245394: 

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r245394 | qcolombet | 2015-08-18 17:07:20 -0700 (Tue, 18 Aug 2015) | 3 lines

[BasicAA] Revert r221876 because it can produce incorrect aliasing
information: see PR24468.

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llvm-svn: 245476
parent 5e1b9055

llvm/lib/Analysis/BasicAliasAnalysis.cpp

+4 −52
Original line number Diff line number Diff line
@@ -206,14 +206,6 @@ static Value *GetLinearExpression(Value *V, APInt &Scale, APInt &Offset, 
    return V;

  }



  if (ConstantInt *Const = dyn_cast<ConstantInt>(V)) {

    // if it's a constant, just convert it to an offset

    // and remove the variable.

    Offset += Const->getValue();

    assert(Scale == 0 && "Constant values don't have a scale");

    return V;

  }



  if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(V)) {

    if (ConstantInt *RHSC = dyn_cast<ConstantInt>(BOp->getOperand(1))) {

      switch (BOp->getOpcode()) {
@@ -261,10 +253,7 @@ static Value *GetLinearExpression(Value *V, APInt &Scale, APInt &Offset, 
    Value *Result = GetLinearExpression(CastOp, Scale, Offset, Extension, DL,

                                        Depth + 1, AC, DT);

    Scale = Scale.zext(OldWidth);



    // We have to sign-extend even if Extension == EK_ZeroExt as we can't

    // decompose a sign extension (i.e. zext(x - 1) != zext(x) - zext(-1)).

    Offset = Offset.sext(OldWidth);

    Offset = Offset.zext(OldWidth);



    return Result;

  }
@@ -1135,43 +1124,12 @@ AliasResult BasicAliasAnalysis::aliasGEP( 
    }

  }



  // Try to distinguish something like &A[i][1] against &A[42][0].

  // Grab the least significant bit set in any of the scales.

  if (!GEP1VariableIndices.empty()) {

    uint64_t Modulo = 0;

    bool AllPositive = true;

    for (unsigned i = 0, e = GEP1VariableIndices.size(); i != e; ++i) {



      // Try to distinguish something like &A[i][1] against &A[42][0].

      // Grab the least significant bit set in any of the scales. We

      // don't need std::abs here (even if the scale's negative) as we'll

      // be ^'ing Modulo with itself later.

    for (unsigned i = 0, e = GEP1VariableIndices.size(); i != e; ++i)

      Modulo |= (uint64_t) GEP1VariableIndices[i].Scale;



      if (AllPositive) {

        // If the Value could change between cycles, then any reasoning about

        // the Value this cycle may not hold in the next cycle. We'll just

        // give up if we can't determine conditions that hold for every cycle:

        const Value *V = GEP1VariableIndices[i].V;



        bool SignKnownZero, SignKnownOne;

        ComputeSignBit(const_cast<Value *>(V), SignKnownZero, SignKnownOne, *DL,

                       0, AC1, nullptr, DT);



        // Zero-extension widens the variable, and so forces the sign

        // bit to zero.

        bool IsZExt = GEP1VariableIndices[i].Extension == EK_ZeroExt;

        SignKnownZero |= IsZExt;

        SignKnownOne &= !IsZExt;



        // If the variable begins with a zero then we know it's

        // positive, regardless of whether the value is signed or

        // unsigned.

        int64_t Scale = GEP1VariableIndices[i].Scale;

        AllPositive =

          (SignKnownZero && Scale >= 0) ||

          (SignKnownOne && Scale < 0);

      }

    }



    Modulo = Modulo ^ (Modulo & (Modulo - 1));



    // We can compute the difference between the two addresses
@@ -1182,12 +1140,6 @@ AliasResult BasicAliasAnalysis::aliasGEP( 
        V2Size != MemoryLocation::UnknownSize && ModOffset >= V2Size &&

        V1Size <= Modulo - ModOffset)

      return NoAlias;



    // If we know all the variables are positive, then GEP1 >= GEP1BasePtr.

    // If GEP1BasePtr > V2 (GEP1BaseOffset > 0) then we know the pointers

    // don't alias if V2Size can fit in the gap between V2 and GEP1BasePtr.

    if (AllPositive && GEP1BaseOffset > 0 && V2Size <= (uint64_t) GEP1BaseOffset)

      return NoAlias;

  }



  // Statically, we can see that the base objects are the same, but the

llvm/test/Analysis/BasicAA/phi-aa.ll

+0 −1
Original line number Diff line number Diff line
@@ -39,7 +39,6 @@ return: 


; CHECK-LABEL: pr18068

; CHECK: MayAlias: i32* %0, i32* %arrayidx5

; CHECK: NoAlias: i32* %arrayidx13, i32* %arrayidx5



define i32 @pr18068(i32* %jj7, i32* %j) {

entry:

llvm/test/Analysis/BasicAA/zext.ll

deleted100644 → 0
+0 −209
Original line number Diff line number Diff line 
; RUN: opt < %s -basicaa -aa-eval -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s

target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"

target triple = "x86_64-unknown-linux-gnu"



; CHECK-LABEL: test_with_zext

; CHECK:  NoAlias: i8* %a, i8* %b



define void @test_with_zext() {

  %1 = tail call i8* @malloc(i64 120)

  %a = getelementptr inbounds i8, i8* %1, i64 8

  %2 = getelementptr inbounds i8, i8* %1, i64 16

  %3 = zext i32 3 to i64

  %b = getelementptr inbounds i8, i8* %2, i64 %3

  ret void

}



; CHECK-LABEL: test_with_lshr

; CHECK:  NoAlias: i8* %a, i8* %b



define void @test_with_lshr(i64 %i) {

  %1 = tail call i8* @malloc(i64 120)

  %a = getelementptr inbounds i8, i8* %1, i64 8

  %2 = getelementptr inbounds i8, i8* %1, i64 16

  %3 = lshr i64 %i, 2

  %b = getelementptr inbounds i8, i8* %2, i64 %3

  ret void

}



; CHECK-LABEL: test_with_a_loop

; CHECK:  NoAlias: i8* %a, i8* %b



define void @test_with_a_loop(i8* %mem) {

  br label %for.loop



for.loop:

  %i = phi i32 [ 0, %0 ], [ %i.plus1, %for.loop ]

  %a = getelementptr inbounds i8, i8* %mem, i64 8

  %a.plus1 = getelementptr inbounds i8, i8* %mem, i64 16

  %i.64 = zext i32 %i to i64

  %b = getelementptr inbounds i8, i8* %a.plus1, i64 %i.64

  %i.plus1 = add nuw nsw i32 %i, 1

  %cmp = icmp eq i32 %i.plus1, 10

  br i1 %cmp, label %for.loop.exit, label %for.loop



for.loop.exit:

  ret void

}



; CHECK-LABEL: test_with_varying_base_pointer_in_loop

; CHECK:  NoAlias: i8* %a, i8* %b



define void @test_with_varying_base_pointer_in_loop(i8* %mem.orig) {

  br label %for.loop



for.loop:

  %mem = phi i8* [ %mem.orig, %0 ], [ %mem.plus1, %for.loop ]

  %i = phi i32 [ 0, %0 ], [ %i.plus1, %for.loop ]

  %a = getelementptr inbounds i8, i8* %mem, i64 8

  %a.plus1 = getelementptr inbounds i8, i8* %mem, i64 16

  %i.64 = zext i32 %i to i64

  %b = getelementptr inbounds i8, i8* %a.plus1, i64 %i.64

  %i.plus1 = add nuw nsw i32 %i, 1

  %mem.plus1 = getelementptr inbounds i8, i8* %mem, i64 8

  %cmp = icmp eq i32 %i.plus1, 10

  br i1 %cmp, label %for.loop.exit, label %for.loop



for.loop.exit:

  ret void

}



; CHECK-LABEL: test_sign_extension

; CHECK:  PartialAlias: i64* %b.i64, i8* %a



define void @test_sign_extension(i32 %p) {

  %1 = tail call i8* @malloc(i64 120)

  %p.64 = zext i32 %p to i64

  %a = getelementptr inbounds i8, i8* %1, i64 %p.64

  %p.minus1 = add i32 %p, -1

  %p.minus1.64 = zext i32 %p.minus1 to i64

  %b.i8 = getelementptr inbounds i8, i8* %1, i64 %p.minus1.64

  %b.i64 = bitcast i8* %b.i8 to i64*

  ret void

}



; CHECK-LABEL: test_fe_tools

; CHECK:  PartialAlias: i32* %a, i32* %b



define void @test_fe_tools([8 x i32]* %values) {

  br label %reorder



for.loop:

  %i = phi i32 [ 0, %reorder ], [ %i.next, %for.loop ]

  %idxprom = zext i32 %i to i64

  %b = getelementptr inbounds [8 x i32], [8 x i32]* %values, i64 0, i64 %idxprom

  %i.next = add nuw nsw i32 %i, 1

  %1 = icmp eq i32 %i.next, 10

  br i1 %1, label %for.loop.exit, label %for.loop



reorder:

  %a = getelementptr inbounds [8 x i32], [8 x i32]* %values, i64 0, i64 1

  br label %for.loop



for.loop.exit:

  ret void

}



@b = global i32 0, align 4

@d = global i32 0, align 4



; CHECK-LABEL: test_spec2006

; CHECK:  PartialAlias: i32** %x, i32** %y



define void @test_spec2006() {

  %h = alloca [1 x [2 x i32*]], align 16

  %d.val = load i32, i32* @d, align 4

  %d.promoted = sext i32 %d.val to i64

  %1 = icmp slt i32 %d.val, 2

  br i1 %1, label %.lr.ph, label %3



.lr.ph:                                           ; preds = %0

  br label %2



; <label>:2                                       ; preds = %.lr.ph, %2

  %i = phi i32 [ %d.val, %.lr.ph ], [ %i.plus1, %2 ]

  %i.promoted = sext i32 %i to i64

  %x = getelementptr inbounds [1 x [2 x i32*]], [1 x [2 x i32*]]* %h, i64 0, i64 %d.promoted, i64 %i.promoted

  %i.plus1 = add nsw i32 %i, 1

  %cmp = icmp slt i32 %i.plus1, 2

  br i1 %cmp, label %2, label %3



; <label>:3                                      ; preds = %._crit_edge, %0

  %y = getelementptr inbounds [1 x [2 x i32*]], [1 x [2 x i32*]]* %h, i64 0, i64 0, i64 1

  ret void

}



; CHECK-LABEL: test_modulo_analysis_easy_case

; CHECK:  NoAlias: i32** %x, i32** %y



define void @test_modulo_analysis_easy_case(i64 %i) {

  %h = alloca [1 x [2 x i32*]], align 16

  %x = getelementptr inbounds [1 x [2 x i32*]], [1 x [2 x i32*]]* %h, i64 0, i64 %i, i64 0

  %y = getelementptr inbounds [1 x [2 x i32*]], [1 x [2 x i32*]]* %h, i64 0, i64 0, i64 1

  ret void

}



; CHECK-LABEL: test_modulo_analysis_in_loop

; CHECK:  NoAlias: i32** %x, i32** %y



define void @test_modulo_analysis_in_loop() {

  %h = alloca [1 x [2 x i32*]], align 16

  br label %for.loop



for.loop:

  %i = phi i32 [ 0, %0 ], [ %i.plus1, %for.loop ]

  %i.promoted = sext i32 %i to i64

  %x = getelementptr inbounds [1 x [2 x i32*]], [1 x [2 x i32*]]* %h, i64 0, i64 %i.promoted, i64 0

  %y = getelementptr inbounds [1 x [2 x i32*]], [1 x [2 x i32*]]* %h, i64 0, i64 0, i64 1

  %i.plus1 = add nsw i32 %i, 1

  %cmp = icmp slt i32 %i.plus1, 2

  br i1 %cmp, label %for.loop, label %for.loop.exit



for.loop.exit:

  ret void

}



; CHECK-LABEL: test_modulo_analysis_with_global

; CHECK:  PartialAlias: i32** %x, i32** %y



define void @test_modulo_analysis_with_global() {

  %h = alloca [1 x [2 x i32*]], align 16

  %b = load i32, i32* @b, align 4

  %b.promoted = sext i32 %b to i64

  br label %for.loop



for.loop:

  %i = phi i32 [ 0, %0 ], [ %i.plus1, %for.loop ]

  %i.promoted = sext i32 %i to i64

  %x = getelementptr inbounds [1 x [2 x i32*]], [1 x [2 x i32*]]* %h, i64 0, i64 %i.promoted, i64 %b.promoted

  %y = getelementptr inbounds [1 x [2 x i32*]], [1 x [2 x i32*]]* %h, i64 0, i64 0, i64 1

  %i.plus1 = add nsw i32 %i, 1

  %cmp = icmp slt i32 %i.plus1, 2

  br i1 %cmp, label %for.loop, label %for.loop.exit



for.loop.exit:

  ret void

}



; CHECK-LABEL: test_const_eval

; CHECK: NoAlias: i8* %a, i8* %b

define void @test_const_eval(i8* %ptr, i64 %offset) {

  %a = getelementptr inbounds i8, i8* %ptr, i64 %offset

  %a.dup = getelementptr inbounds i8, i8* %ptr, i64 %offset

  %three = zext i32 3 to i64

  %b = getelementptr inbounds i8, i8* %a.dup, i64 %three

  ret void

}



; CHECK-LABEL: test_const_eval_scaled

; CHECK: MustAlias: i8* %a, i8* %b

define void @test_const_eval_scaled(i8* %ptr) {

  %three = zext i32 3 to i64

  %six = mul i64 %three, 2

  %a = getelementptr inbounds i8, i8* %ptr, i64 %six

  %b = getelementptr inbounds i8, i8* %ptr, i64 6

  ret void

}



; Function Attrs: nounwind

declare noalias i8* @malloc(i64)