From: Quentin Colombet Date: Wed, 19 Aug 2015 00:07:20 +0000 (+0000) Subject: [BasicAA] Revert r221876 because it can produce incorrect aliasing X-Git-Url: http://plrg.eecs.uci.edu/git/?p=oota-llvm.git;a=commitdiff_plain;h=71f1967057b8520a662949d1cabb97e569268cd8 [BasicAA] Revert r221876 because it can produce incorrect aliasing information: see PR24468. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@245394 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp index c6845ff4370..b73dfa3f72b 100644 --- a/lib/Analysis/BasicAliasAnalysis.cpp +++ b/lib/Analysis/BasicAliasAnalysis.cpp @@ -190,14 +190,6 @@ static bool isObjectSize(const Value *V, uint64_t Size, const DataLayout &DL, return V; } - if (ConstantInt *Const = dyn_cast(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(V)) { if (ConstantInt *RHSC = dyn_cast(BOp->getOperand(1))) { switch (BOp->getOpcode()) { @@ -246,10 +238,7 @@ static bool isObjectSize(const Value *V, uint64_t Size, const DataLayout &DL, 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; } @@ -959,42 +948,12 @@ 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(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 @@ -1005,12 +964,6 @@ 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 diff --git a/test/Analysis/BasicAA/phi-aa.ll b/test/Analysis/BasicAA/phi-aa.ll index 3944e9e4356..a72778277bb 100644 --- a/test/Analysis/BasicAA/phi-aa.ll +++ b/test/Analysis/BasicAA/phi-aa.ll @@ -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: diff --git a/test/Analysis/BasicAA/zext.ll b/test/Analysis/BasicAA/zext.ll deleted file mode 100644 index ed356564025..00000000000 --- a/test/Analysis/BasicAA/zext.ll +++ /dev/null @@ -1,209 +0,0 @@ -; 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 - -;