Index: lib/Analysis/LoopAccessAnalysis.cpp =================================================================== --- lib/Analysis/LoopAccessAnalysis.cpp +++ lib/Analysis/LoopAccessAnalysis.cpp @@ -743,6 +743,11 @@ GetUnderlyingObjects(Ptr, TempObjects, DL, LI); DEBUG(dbgs() << "Underlying objects for pointer " << *Ptr << "\n"); for (Value *UnderlyingObj : TempObjects) { + // nullptr never alias, don't join sets for pointer that have "null" + // in their UnderlyingObjects list. + if (isa(UnderlyingObj)) { + continue; + } UnderlyingObjToAccessMap::iterator Prev = ObjToLastAccess.find(UnderlyingObj); if (Prev != ObjToLastAccess.end()) Index: test/Analysis/LoopAccessAnalysis/nullptr.ll =================================================================== --- /dev/null +++ test/Analysis/LoopAccessAnalysis/nullptr.ll @@ -0,0 +1,31 @@ +;RUN: opt -loop-accesses -analyze %s | FileCheck %s +; CHECK: Memory dependences are safe with run-time checks + +; ModuleID = 'bugpoint-reduced-simplified.bc' +target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128" +target triple = "x86_64-apple-macosx10.11.0" + +; Function Attrs: ssp uwtable +define void @foo(i1 %cond, i32* %ptr1, i32* %ptr2) { + br i1 %cond, label %.preheader, label %diamond + +diamond: ; preds = %.noexc.i.i + br label %.preheader + +.preheader: ; preds = %diamond, %0 + %ptr1_or_null = phi i32* [ null, %0 ], [ %ptr1, %diamond ] + %ptr2_or_null = phi i32* [ null, %0 ], [ %ptr2, %diamond ] + br label %.lr.ph + +.lr.ph: ; preds = %.lr.ph, %.preheader + %indvars.iv = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 10, %.preheader ] + %indvars.iv.next = add nsw i64 %indvars.iv, -1 + %tmp4 = getelementptr inbounds i32, i32* %ptr2_or_null, i64 %indvars.iv.next + %tmp5 = load i32, i32* %tmp4, align 4 + %tmp6 = getelementptr inbounds i32, i32* %ptr1_or_null, i64 %indvars.iv.next + store i32 undef, i32* %tmp6, align 4 + br i1 false, label %.lr.ph, label %.end + +.end: + ret void +}