diff --git a/lib/Transforms/Scalar/JumpThreading.cpp b/lib/Transforms/Scalar/JumpThreading.cpp index fbb5c201347..25a8b0cdbd3 100644 --- a/lib/Transforms/Scalar/JumpThreading.cpp +++ b/lib/Transforms/Scalar/JumpThreading.cpp @@ -1035,10 +1035,13 @@ bool JumpThreading::SimplifyPartiallyRedundantLoad(LoadInst *LI) { "Didn't find entry for predecessor!"); // If we have an available predecessor but it requires casting, insert the - // cast in the predecessor and use the cast. - Value *PredV = I->second; + // cast in the predecessor and use the cast. Note that we have to update the + // AvailablePreds vector as we go so that all of the PHI entries for this + // predecessor use the same bitcast. + Value *&PredV = I->second; if (PredV->getType() != LI->getType()) - PredV = CastInst::Create(CastInst::BitCast, PredV, LI->getType(), "", P); + PredV = CastInst::Create(CastInst::BitCast, PredV, LI->getType(), "", + P->getTerminator()); PN->addIncoming(PredV, I->first); } diff --git a/test/Transforms/JumpThreading/thread-loads.ll b/test/Transforms/JumpThreading/thread-loads.ll index e5bf64b9e25..b13b767bdea 100644 --- a/test/Transforms/JumpThreading/thread-loads.ll +++ b/test/Transforms/JumpThreading/thread-loads.ll @@ -75,6 +75,37 @@ bb3: ; preds = %bb1 ret i32 %res.0 } +define i32 @test3(i8** %x, i1 %f) { +; Correctly thread loads of different (but compatible) types, placing bitcasts +; as necessary in the predecessors. This is especially tricky because the same +; predecessor ends up with two entries in the PHI node and they must share +; a single cast. +; CHECK-LABEL: @test3( +entry: + %0 = bitcast i8** %x to i32** + %1 = load i32** %0, align 8 + br i1 %f, label %if.end57, label %if.then56 +; CHECK: %[[LOAD:.*]] = load i32** +; CHECK: %[[CAST:.*]] = bitcast i32* %[[LOAD]] to i8* + +if.then56: + br label %if.end57 + +if.end57: + %2 = load i8** %x, align 8 + %tobool59 = icmp eq i8* %2, null + br i1 %tobool59, label %return, label %if.then60 +; CHECK: %[[PHI:.*]] = phi i8* [ %[[CAST]], %[[PRED:[^ ]+]] ], [ %[[CAST]], %[[PRED]] ] +; CHECK-NEXT: %[[CMP:.*]] = icmp eq i8* %[[PHI]], null +; CHECK-NEXT: br i1 %[[CMP]] + +if.then60: + ret i32 42 + +return: + ret i32 13 +} + !0 = metadata !{metadata !3, metadata !3, i64 0} !1 = metadata !{metadata !"omnipotent char", metadata !2} !2 = metadata !{metadata !"Simple C/C++ TBAA", null}