Value *Result = GetLinearExpression(CastOp, Scale, Offset, Extension,
DL, Depth+1, AT, DT);
Scale = Scale.zext(OldWidth);
- Offset = Offset.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);
return Result;
}
// Grab the least significant bit set in any of the scales.
if (!GEP1VariableIndices.empty()) {
uint64_t Modulo = 0;
- for (unsigned i = 0, e = GEP1VariableIndices.size(); i != e; ++i)
+ bool AllPositive = true;
+ for (unsigned i = 0, e = GEP1VariableIndices.size();
+ i != e && AllPositive; ++i) {
+ const Value *V = GEP1VariableIndices[i].V;
Modulo |= (uint64_t)GEP1VariableIndices[i].Scale;
+
+ bool SignKnownZero, SignKnownOne;
+ ComputeSignBit(
+ const_cast<Value *>(V),
+ SignKnownZero, SignKnownOne,
+ DL, 0, AT, 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);
+
+ // If the Value is currently positive but could change in a cycle,
+ // then we can't guarantee it'll always br positive.
+ if (AllPositive && !isValueEqualInPotentialCycles(V, V))
+ AllPositive = false;
+ }
+
Modulo = Modulo ^ (Modulo & (Modulo - 1));
// We can compute the difference between the two addresses
if (V1Size != UnknownSize && V2Size != 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
--- /dev/null
+; 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* %1, i64 8
+ %2 = getelementptr inbounds i8* %1, i64 16
+ %3 = zext i32 3 to i64
+ %b = getelementptr inbounds 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* %1, i64 8
+ %2 = getelementptr inbounds i8* %1, i64 16
+ %3 = lshr i64 %i, 2
+ %b = getelementptr inbounds i8* %2, i64 %3
+ ret void
+}
+
+; CHECK-LABEL: test_with_a_loop
+; CHECK: NoAlias: i8* %a, i8* %b
+
+define void @test_with_a_loop() {
+ %1 = tail call i8* @malloc(i64 120)
+ %a = getelementptr inbounds i8* %1, i64 8
+ %2 = getelementptr inbounds i8* %1, i64 16
+ br label %for.loop
+
+for.loop:
+ %i = phi i32 [ 0, %0 ], [ %i.next, %for.loop ]
+ %3 = zext i32 %i to i64
+ %b = getelementptr inbounds i8* %2, i64 %3
+ %i.next = add nuw nsw i32 %i, 1
+ %4 = icmp eq i32 %i.next, 10
+ br i1 %4, 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* %1, i64 %p.64
+ %p.minus1 = add i32 %p, -1
+ %p.minus1.64 = zext i32 %p.minus1 to i64
+ %b.i8 = getelementptr inbounds 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]* %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]* %values, i64 0, i64 1
+ br label %for.loop
+
+for.loop.exit:
+ ret void
+}
+
+; Function Attrs: nounwind
+declare noalias i8* @malloc(i64)