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