test/Transforms/LoopVectorize/X86/illegal-parallel-loop-uniform-write.ll

; RUN: opt < %s  -loop-vectorize -force-vector-interleave=1 -force-vector-width=4 -dce -instcombine -S | FileCheck %s

target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

; CHECK-LABEL: @foo(
; CHECK: <4 x i32>
; CHECK: ret void

; PR15794
; incorrect addition of llvm.mem.parallel_loop_access metadata is undefined
; behaviour. Vectorizer ignores the memory dependency checks and goes ahead and
; vectorizes this loop with uniform stores which has an output dependency.

; void foo(int *a, int *b, int k, int m) {
;   for (int i = 0; i < m; i++) {
;     for (int j = 0; j < m; j++) {
;       a[i] = a[i + j + k] + 1; <<<
;     }
;     b[i] = b[i] + 3;
;   }
; }

; Function Attrs: nounwind uwtable 
define void @foo(i32* nocapture %a, i32* nocapture %b, i32 %k, i32 %m) #0 {
entry:
  %cmp27 = icmp sgt i32 %m, 0
  br i1 %cmp27, label %for.body3.lr.ph.us, label %for.end15

for.end.us:                                       ; preds = %for.body3.us
  %arrayidx9.us = getelementptr inbounds i32, i32* %b, i64 %indvars.iv33
  %0 = load i32, i32* %arrayidx9.us, align 4, !llvm.mem.parallel_loop_access !3
  %add10.us = add nsw i32 %0, 3
  store i32 %add10.us, i32* %arrayidx9.us, align 4, !llvm.mem.parallel_loop_access !3
  %indvars.iv.next34 = add i64 %indvars.iv33, 1
  %lftr.wideiv35 = trunc i64 %indvars.iv.next34 to i32
  %exitcond36 = icmp eq i32 %lftr.wideiv35, %m
  br i1 %exitcond36, label %for.end15, label %for.body3.lr.ph.us, !llvm.loop !5

for.body3.us:                                     ; preds = %for.body3.us, %for.body3.lr.ph.us
  %indvars.iv29 = phi i64 [ 0, %for.body3.lr.ph.us ], [ %indvars.iv.next30, %for.body3.us ]
  %1 = trunc i64 %indvars.iv29 to i32
  %add4.us = add i32 %add.us, %1
  %idxprom.us = sext i32 %add4.us to i64
  %arrayidx.us = getelementptr inbounds i32, i32* %a, i64 %idxprom.us
  %2 = load i32, i32* %arrayidx.us, align 4, !llvm.mem.parallel_loop_access !3
  %add5.us = add nsw i32 %2, 1
  store i32 %add5.us, i32* %arrayidx7.us, align 4, !llvm.mem.parallel_loop_access !3
  %indvars.iv.next30 = add i64 %indvars.iv29, 1
  %lftr.wideiv31 = trunc i64 %indvars.iv.next30 to i32
  %exitcond32 = icmp eq i32 %lftr.wideiv31, %m
  br i1 %exitcond32, label %for.end.us, label %for.body3.us, !llvm.loop !4

for.body3.lr.ph.us:                               ; preds = %for.end.us, %entry
  %indvars.iv33 = phi i64 [ %indvars.iv.next34, %for.end.us ], [ 0, %entry ]
  %3 = trunc i64 %indvars.iv33 to i32
  %add.us = add i32 %3, %k
  %arrayidx7.us = getelementptr inbounds i32, i32* %a, i64 %indvars.iv33
  br label %for.body3.us

for.end15:                                        ; preds = %for.end.us, %entry
  ret void
}

; Same test as above, but without the invalid parallel_loop_access metadata.

; Here we can see the vectorizer does the mem dep checks and decides it is
; unsafe to vectorize.
; CHECK-LABEL: no-par-mem-metadata(
; CHECK-NOT: <4 x i32>
; CHECK:     ret void
define void @no-par-mem-metadata(i32* nocapture %a, i32* nocapture %b, i32 %k, i32 %m) #0 {
entry:
  %cmp27 = icmp sgt i32 %m, 0
  br i1 %cmp27, label %for.body3.lr.ph.us, label %for.end15

for.end.us:                                       ; preds = %for.body3.us
  %arrayidx9.us = getelementptr inbounds i32, i32* %b, i64 %indvars.iv33
  %0 = load i32, i32* %arrayidx9.us, align 4
  %add10.us = add nsw i32 %0, 3
  store i32 %add10.us, i32* %arrayidx9.us, align 4
  %indvars.iv.next34 = add i64 %indvars.iv33, 1
  %lftr.wideiv35 = trunc i64 %indvars.iv.next34 to i32
  %exitcond36 = icmp eq i32 %lftr.wideiv35, %m
  br i1 %exitcond36, label %for.end15, label %for.body3.lr.ph.us, !llvm.loop !5

for.body3.us:                                     ; preds = %for.body3.us, %for.body3.lr.ph.us
  %indvars.iv29 = phi i64 [ 0, %for.body3.lr.ph.us ], [ %indvars.iv.next30, %for.body3.us ]
  %1 = trunc i64 %indvars.iv29 to i32
  %add4.us = add i32 %add.us, %1
  %idxprom.us = sext i32 %add4.us to i64
  %arrayidx.us = getelementptr inbounds i32, i32* %a, i64 %idxprom.us
  %2 = load i32, i32* %arrayidx.us, align 4
  %add5.us = add nsw i32 %2, 1
  store i32 %add5.us, i32* %arrayidx7.us, align 4
  %indvars.iv.next30 = add i64 %indvars.iv29, 1
  %lftr.wideiv31 = trunc i64 %indvars.iv.next30 to i32
  %exitcond32 = icmp eq i32 %lftr.wideiv31, %m
  br i1 %exitcond32, label %for.end.us, label %for.body3.us, !llvm.loop !4

for.body3.lr.ph.us:                               ; preds = %for.end.us, %entry
  %indvars.iv33 = phi i64 [ %indvars.iv.next34, %for.end.us ], [ 0, %entry ]
  %3 = trunc i64 %indvars.iv33 to i32
  %add.us = add i32 %3, %k
  %arrayidx7.us = getelementptr inbounds i32, i32* %a, i64 %indvars.iv33
  br label %for.body3.us

for.end15:                                        ; preds = %for.end.us, %entry
  ret void
}

attributes #0 = { nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-frame-pointer-elim-non-leaf"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="false" }

!3 = !{!4, !5}
!4 = !{!4}
!5 = !{!5}