Index: llvm/lib/Transforms/Utils/SimplifyIndVar.cpp =================================================================== --- llvm/lib/Transforms/Utils/SimplifyIndVar.cpp +++ llvm/lib/Transforms/Utils/SimplifyIndVar.cpp @@ -281,8 +281,11 @@ // If the condition is always true or always false in the given context, // replace it with a constant value. - // TODO: We can sharpen the context to common dominator of all ICmp's users. - if (auto Ev = SE->evaluatePredicateAt(Pred, S, X, ICmp)) { + SmallVector Users; + for (auto *U : ICmp->users()) + Users.push_back(cast(U)); + const Instruction *CtxI = findCommonDominator(Users, *DT); + if (auto Ev = SE->evaluatePredicateAt(Pred, S, X, CtxI)) { ICmp->replaceAllUsesWith(ConstantInt::getBool(ICmp->getContext(), *Ev)); DeadInsts.emplace_back(ICmp); LLVM_DEBUG(dbgs() << "INDVARS: Eliminated comparison: " << *ICmp << '\n'); Index: llvm/test/Transforms/IndVarSimplify/eliminate-comparison.ll =================================================================== --- llvm/test/Transforms/IndVarSimplify/eliminate-comparison.ll +++ llvm/test/Transforms/IndVarSimplify/eliminate-comparison.ll @@ -1101,13 +1101,11 @@ ; CHECK: loop: ; CHECK-NEXT: [[IV:%.*]] = phi i32 [ [[START:%.*]], [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ] ; CHECK-NEXT: [[C1:%.*]] = icmp ne i32 [[IV]], 0 -; CHECK-NEXT: [[C2:%.*]] = icmp ne i32 [[IV]], 0 -; CHECK-NEXT: [[C3:%.*]] = icmp ne i32 [[IV]], 0 ; CHECK-NEXT: br i1 [[C1]], label [[CHECKED_1:%.*]], label [[FAIL:%.*]] ; CHECK: checked.1: -; CHECK-NEXT: br i1 [[C2]], label [[CHECKED_2:%.*]], label [[FAIL]] +; CHECK-NEXT: br i1 true, label [[CHECKED_2:%.*]], label [[FAIL]] ; CHECK: checked.2: -; CHECK-NEXT: br i1 [[C3]], label [[BACKEDGE]], label [[FAIL]] +; CHECK-NEXT: br i1 true, label [[BACKEDGE]], label [[FAIL]] ; CHECK: backedge: ; CHECK-NEXT: [[IV_NEXT]] = add i32 [[IV]], 758394 ; CHECK-NEXT: [[LOOP_COND:%.*]] = call i1 @cond_func()