diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp --- a/llvm/lib/Analysis/ScalarEvolution.cpp +++ b/llvm/lib/Analysis/ScalarEvolution.cpp @@ -8235,14 +8235,18 @@ if (!MultipleInitValues && InitValue) return getSCEV(InitValue); } - // Do we have a loop invariant value flowing around the backedge + // Do we have a PHI value we can materialize // for a loop which must execute the backedge? if (!isa(BackedgeTakenCount) && isKnownPositive(BackedgeTakenCount) && PN->getNumIncomingValues() == 2) { unsigned InLoopPred = LI->contains(PN->getIncomingBlock(0)) ? 0 : 1; - const SCEV *OnBackedge = getSCEV(PN->getIncomingValue(InLoopPred)); - if (IsAvailableOnEntry(LI, DT, OnBackedge, PN->getParent())) + BasicBlock *Header = PN->getParent(); + Value *BackedgeVal = PN->getIncomingValue(InLoopPred); + const SCEV *OnBackedge = getSCEV(BackedgeVal); + if (!(isa(BackedgeVal) && + cast(BackedgeVal)->getParent() == Header) && + IsAvailableOnEntry(LI, DT, OnBackedge, Header)) return OnBackedge; } if (auto *BTCC = dyn_cast(BackedgeTakenCount)) { diff --git a/llvm/test/Analysis/ScalarEvolution/pr44605.ll b/llvm/test/Analysis/ScalarEvolution/pr44605.ll new file mode 100644 --- /dev/null +++ b/llvm/test/Analysis/ScalarEvolution/pr44605.ll @@ -0,0 +1,67 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py +; NOTE: Only %local_6_6 and %local_3_4 nodes are important here. +; All other instructions are needed to lure LLVM into executing +; specific code to trigger a bug. +; RUN: opt < %s -indvars -S | FileCheck %s +define i32 @test() { +; CHECK-LABEL: @test( +; CHECK-NEXT: entry: +; CHECK-NEXT: br label [[OUTER:%.*]] +; CHECK: outer: +; CHECK-NEXT: [[LOCAL_6_6:%.*]] = phi i32 [ 10, [[ENTRY:%.*]] ], [ [[TMP5:%.*]], [[LATCH:%.*]] ] +; CHECK-NEXT: [[LOCAL_4_5:%.*]] = phi i32 [ 56587, [[ENTRY]] ], [ 0, [[LATCH]] ] +; CHECK-NEXT: [[LOCAL_3_4:%.*]] = phi i32 [ 2, [[ENTRY]] ], [ [[LOCAL_6_6]], [[LATCH]] ] +; CHECK-NEXT: [[DOTUDIV:%.*]] = udiv i32 [[LOCAL_6_6]], 8361 +; CHECK-NEXT: br label [[INNER:%.*]] +; CHECK: inner: +; CHECK-NEXT: [[LOCAL_7_3:%.*]] = phi i32 [ 2, [[OUTER]] ], [ [[TMP3:%.*]], [[INNER]] ] +; CHECK-NEXT: [[LOCAL_4_5_PN:%.*]] = phi i32 [ [[LOCAL_4_5]], [[OUTER]] ], [ [[TMP2:%.*]], [[INNER]] ] +; CHECK-NEXT: [[LOCAL_3_31:%.*]] = mul i32 [[LOCAL_4_5_PN]], [[DOTUDIV]] +; CHECK-NEXT: [[TMP0:%.*]] = mul nuw nsw i32 [[LOCAL_7_3]], [[DOTUDIV]] +; CHECK-NEXT: [[TMP1:%.*]] = sub i32 [[TMP0]], [[LOCAL_3_4]] +; CHECK-NEXT: [[TMP2]] = add i32 [[TMP1]], [[LOCAL_3_31]] +; CHECK-NEXT: [[TMP3]] = add nuw nsw i32 [[LOCAL_7_3]], 1 +; CHECK-NEXT: [[TMP4:%.*]] = icmp ugt i32 [[LOCAL_7_3]], 4 +; CHECK-NEXT: br i1 [[TMP4]], label [[LATCH]], label [[INNER]] +; CHECK: latch: +; CHECK-NEXT: [[DOTLCSSA:%.*]] = phi i32 [ [[TMP2]], [[INNER]] ] +; CHECK-NEXT: [[TMP5]] = add nuw nsw i32 [[LOCAL_6_6]], 1 +; CHECK-NEXT: [[TMP6:%.*]] = icmp ugt i32 [[LOCAL_6_6]], 276 +; CHECK-NEXT: br i1 [[TMP6]], label [[RETURN:%.*]], label [[OUTER]] +; CHECK: return: +; CHECK-NEXT: [[DOTLCSSA_LCSSA:%.*]] = phi i32 [ [[DOTLCSSA]], [[LATCH]] ] +; CHECK-NEXT: ret i32 [[DOTLCSSA_LCSSA]] +; +entry: + br label %outer + +outer: + %local_6_6 = phi i32 [ 10, %entry ], [ %5, %latch ] + %local_4_5 = phi i32 [ 56587, %entry ], [ 0, %latch ] + %local_3_4 = phi i32 [ 2, %entry ], [ %local_6_6, %latch ] + %.udiv = udiv i32 %local_6_6, 8361 + br label %inner + +inner: + %local_7_3 = phi i32 [ 2, %outer ], [ %3, %inner ] + %local_4_5.pn = phi i32 [ %local_4_5, %outer ], [ %2, %inner ] + %local_3_31 = mul i32 %local_4_5.pn, %.udiv + %0 = mul i32 %local_7_3, %.udiv + %1 = sub i32 %0, %local_3_4 + %2 = add i32 %1, %local_3_31 + %3 = add nuw nsw i32 %local_7_3, 1 + %4 = icmp ugt i32 %local_7_3, 4 + br i1 %4, label %latch, label %inner + +latch: + %.lcssa = phi i32 [ %2, %inner ] + %5 = add nuw nsw i32 %local_6_6, 1 + %6 = icmp ugt i32 %local_6_6, 276 + br i1 %6, label %return, label %outer + +return: + %.lcssa.lcssa = phi i32 [ %.lcssa, %latch ] + ret i32 %.lcssa.lcssa + +} +