| ; RUN: opt < %s -S -unroll-runtime -unroll-count=2 -loop-unroll | FileCheck %s |
| target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128" |
| |
| ; This test case documents how runtime loop unrolling handles the case |
| ; when the backedge-count is -1. |
| |
| ; If %N, the backedge-taken count, is -1 then %0 unsigned-overflows |
| ; and is 0. %xtraiter too is 0, signifying that the total trip-count |
| ; is divisible by 2. The prologue then branches to the unrolled loop |
| ; and executes the 2^32 iterations there, in groups of 2. |
| |
| |
| ; CHECK: entry: |
| ; CHECK-NEXT: %0 = add i32 %N, 1 |
| ; CHECK-NEXT: %xtraiter = and i32 %0, 1 |
| ; CHECK-NEXT: %lcmp.mod = icmp ne i32 %xtraiter, 0 |
| ; CHECK-NEXT: br i1 %lcmp.mod, label %while.body.prol, label %entry.split |
| |
| ; CHECK: while.body.prol: |
| ; CHECK: br label %entry.split |
| |
| ; CHECK: entry.split: |
| |
| ; Function Attrs: nounwind readnone ssp uwtable |
| define i32 @foo(i32 %N) { |
| entry: |
| br label %while.body |
| |
| while.body: ; preds = %while.body, %entry |
| %i = phi i32 [ 0, %entry ], [ %inc, %while.body ] |
| %cmp = icmp eq i32 %i, %N |
| %inc = add i32 %i, 1 |
| br i1 %cmp, label %while.end, label %while.body |
| |
| while.end: ; preds = %while.body |
| ret i32 %i |
| } |
