llvm/test/Transforms/PhaseOrdering/single-iteration-loop-oz.ll

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
; RUN: opt -passes='default<O2>' -S < %s | FileCheck %s

; Verify that a single-iteration loop at -Oz (minsize) is eliminated early
; enough in the pipeline for mid-pipeline passes such as DSE to optimize across
; it, even when the loop body contains calls that prevent full unrolling at
; minsize.

declare void @g(ptr)

define void @single_iter_loop_minsize(ptr noalias %p, ptr noalias %q) minsize optsize {
; CHECK-LABEL: define void @single_iter_loop_minsize(
; CHECK-SAME: ptr noalias [[P:%.*]], ptr noalias nofree writeonly captures(none) initializes((0, 4)) [[Q:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] {
; CHECK-NEXT:  [[ENTRY:.*:]]
; CHECK-NEXT:    tail call void @g(ptr [[P]])
; CHECK-NEXT:    tail call void @g(ptr [[P]])
; CHECK-NEXT:    tail call void @g(ptr [[P]])
; CHECK-NEXT:    store i32 0, ptr [[Q]], align 4
; CHECK-NEXT:    store i32 42, ptr [[P]], align 4
; CHECK-NEXT:    ret void
;
entry:
  %i = alloca i32, align 4
  store i32 0, ptr %i, align 4
  br label %for.cond

for.cond:
  %0 = load i32, ptr %i, align 4
  %cmp = icmp slt i32 %0, 1
  br i1 %cmp, label %for.body, label %for.end

for.body:
  call void @g(ptr %p)
  call void @g(ptr %p)
  call void @g(ptr %p)
  store i32 10, ptr %p, align 4
  br label %for.inc

for.inc:
  %1 = load i32, ptr %i, align 4
  %inc = add nsw i32 %1, 1
  store i32 %inc, ptr %i, align 4
  br label %for.cond

for.end:
  store i32 0, ptr %q, align 4
  store i32 42, ptr %p, align 4
  ret void
}