Index: llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp =================================================================== --- llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -5400,7 +5400,9 @@ CollectFixupsAndInitialFormulae(); CollectLoopInvariantFixupsAndFormulae(); - assert(!Uses.empty() && "IVUsers reported at least one use"); + if (Uses.empty()) + return; + LLVM_DEBUG(dbgs() << "LSR found " << Uses.size() << " uses:\n"; print_uses(dbgs())); Index: llvm/test/CodeGen/X86/lsr-crash-empty-uses.ll =================================================================== --- /dev/null +++ llvm/test/CodeGen/X86/lsr-crash-empty-uses.ll @@ -0,0 +1,41 @@ +; RUN: llc --start-before loop-reduce --stop-after loop-reduce %s -o - | FileCheck %s +target triple = "x86_64-unknown-linux-gnu" + +; CHECK-LABEL: @Foo +define void @Foo() { +entry: + %idx.ext130 = sext i32 undef to i64 + %idx.neg = sub nsw i64 0, %idx.ext130 + br label %for.body119 + +for.body119: ; preds = %_ZSt10accumulateIPddET0_T_S2_S1_.exit138, %entry + %add.ptr129 = getelementptr inbounds double, double* undef, i64 undef + %add.ptr131 = getelementptr inbounds double, double* %add.ptr129, i64 %idx.neg + br label %for.body.i136.prol + +for.body.i136.prol: ; preds = %for.body.i136.prol, %for.body119 + %__first.addr.04.i132.prol = phi double* [ %incdec.ptr.i134.prol, %for.body.i136.prol ], [ %add.ptr131, %for.body119 ] + %0 = load double, double* %__first.addr.04.i132.prol + %incdec.ptr.i134.prol = getelementptr inbounds double, double* %__first.addr.04.i132.prol, i64 1 + br i1 true, label %for.body.i136.prol.loopexit, label %for.body.i136.prol + +for.body.i136.prol.loopexit: ; preds = %for.body.i136.prol + br i1 undef, label %_ZSt10accumulateIPddET0_T_S2_S1_.exit138, label %for.body.i136.preheader + +for.body.i136.preheader: ; preds = %for.body.i136.prol.loopexit + br label %for.body.i136 + +for.body.i136: ; preds = %for.body.i136.preheader, %for.body.i136 + %__first.addr.04.i132 = phi double* [ %incdec.ptr.i134.7, %for.body.i136 ], [ %incdec.ptr.i134.prol, %for.body.i136.preheader ] + %tmp1 = load double, double* %__first.addr.04.i132, align 8 + %incdec.ptr.i134 = getelementptr inbounds double, double* %__first.addr.04.i132, i64 1 + %tmp2 = load double, double* %incdec.ptr.i134, align 8 + %incdec.ptr.i134.7 = getelementptr inbounds double, double* %__first.addr.04.i132, i64 8 + br i1 true, label %_ZSt10accumulateIPddET0_T_S2_S1_.exit138.loopexit, label %for.body.i136 + +_ZSt10accumulateIPddET0_T_S2_S1_.exit138.loopexit: ; preds = %for.body.i136 + br label %_ZSt10accumulateIPddET0_T_S2_S1_.exit138 + +_ZSt10accumulateIPddET0_T_S2_S1_.exit138: ; preds = %_ZSt10accumulateIPddET0_T_S2_S1_.exit138.loopexit, %for.body.i136.prol.loopexit + br label %for.body119 +}