1; RUN: opt < %s -S -indvars -loop-unroll | FileCheck %s 2; 3; PR15570: SEGV: SCEV back-edge info invalid after dead code removal. 4; 5; Indvars creates a SCEV expression for the loop's back edge taken 6; count, then determines that the comparison is always true and 7; removes it. 8; 9; When loop-unroll asks for the expression, it contains a NULL 10; SCEVUnknkown (as a CallbackVH). 11; 12; forgetMemoizedResults should invalidate the backedge taken count expression. 13 14; CHECK: @test 15; CHECK-NOT: phi 16; CHECK-NOT: icmp 17; CHECK: ret void 18define void @test() { 19entry: 20 %xor1 = xor i32 0, 1 21 br label %b17 22 23b17: 24 br i1 undef, label %b22, label %b18 25 26b18: 27 %phi1 = phi i32 [ %add1, %b18 ], [ %xor1, %b17 ] 28 %add1 = add nsw i32 %phi1, -1 29 %cmp1 = icmp sgt i32 %add1, 0 30 br i1 %cmp1, label %b18, label %b22 31 32b22: 33 ret void 34} 35