1; RUN: opt < %s -S -unroll-runtime -unroll-count=2 -loop-unroll | FileCheck %s -check-prefix=EPILOG 2; RUN: opt < %s -S -unroll-runtime -unroll-count=2 -loop-unroll -unroll-runtime-epilog=false | FileCheck %s -check-prefix=PROLOG 3target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128" 4 5; This test case documents how runtime loop unrolling handles the case 6; when the backedge-count is -1. 7 8; If %N, the backedge-taken count, is -1 then %0 unsigned-overflows 9; and is 0. %xtraiter too is 0, signifying that the total trip-count 10; is divisible by 2. The prologue then branches to the unrolled loop 11; and executes the 2^32 iterations there, in groups of 2. 12 13; EPILOG: entry: 14 15; EPILOG-NEXT: %0 = add i32 %N, 1 16; EPILOG-NEXT: %xtraiter = and i32 %0, 1 17; EPILOG-NEXT: %1 = icmp ult i32 %N, 1 18; EPILOG-NEXT: br i1 %1, label %while.end.unr-lcssa, label %entry.new 19; EPILOG: while.body: 20 21; EPILOG: %lcmp.mod = icmp ne i32 %xtraiter, 0 22; EPILOG-NEXT: br i1 %lcmp.mod, label %while.body.epil.preheader, label %while.end 23; EPILOG: while.body.epil: 24 25; PROLOG: entry: 26; PROLOG-NEXT: %0 = add i32 %N, 1 27; PROLOG-NEXT: %xtraiter = and i32 %0, 1 28; PROLOG-NEXT: %lcmp.mod = icmp ne i32 %xtraiter, 0 29; PROLOG-NEXT: br i1 %lcmp.mod, label %while.body.prol.preheader, label %while.body.prol.loopexit 30; PROLOG: while.body.prol: 31 32; PROLOG: %1 = icmp ult i32 %N, 1 33; PROLOG-NEXT: br i1 %1, label %while.end, label %entry.new 34; PROLOG: while.body: 35 36; Function Attrs: nounwind readnone ssp uwtable 37define i32 @foo(i32 %N) { 38entry: 39 br label %while.body 40 41while.body: ; preds = %while.body, %entry 42 %i = phi i32 [ 0, %entry ], [ %inc, %while.body ] 43 %cmp = icmp eq i32 %i, %N 44 %inc = add i32 %i, 1 45 br i1 %cmp, label %while.end, label %while.body 46 47while.end: ; preds = %while.body 48 ret i32 %i 49} 50